Temperature Measurement Integrity

If you aren’t worried about the integrity of historical temperature data under the care of folks like James Hansen, then you will be after reading this at Climate Audit.

Since August 1, 2007, NASA has had 3 substantially different online versions of their 1221 USHCN stations (1221 in total.) The third and most recent version was slipped in without any announcement or notice in the last few days – subsequent to their code being placed online on Sept 7, 2007. (I can vouch for this as I completed a scrape of the dset=1 dataset in the early afternoon of Sept 7.)

We’ve been following the progress of the Detroit Lakes MN station and it’s instructive to follow the ups and downs of its history through these spasms. One is used to unpredictability in futures markets (I worked in the copper business in the 1970s and learned their vagaries first hand). But it’s quite unexpected to see similar volatility in the temperature “pasts”.

For example, the Oct 1931 value (GISS dset0 and dset1 – both are equal) for Detroit Lakes began August 2007 at 8.2 deg C; there was a short bull market in August with an increase to 9.1 deg C for a few weeks, but its value was hit by the September bear market and is now only 8.5 deg C. The Nov 1931 temperature went up by 0.8 deg (from -0.9 deg C to -0.1 deg C) in the August bull market, but went back down the full amount of 0.8 deg in the September bear market. December 1931 went up a full 1.0 deg C in the August bull market (from -7.6 deg C to -6.6 deg C) and has held onto its gains much better in the September bear market, falling back only 0.1 deg C -6.7 deg C.

Note the volatility of historic temperature numbers.  Always with a steady bias – recent temepratures are adjusted up, older temperatures are adjusted down, giving a net result of more warming.  By the way, think about what these adjustments mean — adjusting recent temperatures down means that our growing urban society and hot cities are somehow introducing a recent cooling bias in measurement.  And adjusting older temepratures down means that in the more rural society of 50 years ago we had more warming biases than we have today.  Huh?

Court Throws Out California Global Warming Suit

Via Q&O:

A federal judge on Monday tossed out a lawsuit filed by California that sought to hold the world’s six largest automakers accountable for their contribution to global warming. District Judge Martin Jenkins in San Francisco handed California Attorney General Jerry Brown’s environmental crusade a stinging rebuke when he ruled that it was impossible to determine to what extent automakers are responsible for global-warming damages in California. The judge also ruled that keeping the lawsuit alive would threaten the country’s foreign policy position.

I would also add that it is impossible to determine how much CO2 has affected warming, or what weather effects might be the result of such warming or just from normal variation.  Further, while areas like the Arctic are clearly warming, it is not at all clear that the US has experienced much warming in the last century.

Less than Meets the Eye in Peer-Reviewed Studies

This comes out of the medical field but sounds about right for climate (WSJ$, emphasis added)

Dr. Ioannidis is an epidemiologist who studies research methods at the University of Ioannina School of Medicine in Greece and Tufts University in Medford, Mass. In a series of influential analytical reports, he has documented how, in thousands of peer-reviewed research papers published every year, there may be so much less than meets the eye.

These flawed findings, for the most part, stem not from fraud or formal misconduct, but from more mundane misbehavior: miscalculation, poor study design or self-serving data analysis. "There is an increasing concern that in modern research, false findings may be the majority or even the vast majority of published research claims," Dr. Ioannidis said. "A new claim about a research finding is more likely to be false than true."

The hotter the field of research the more likely its published findings should be viewed skeptically, he determined….

Statistically speaking, science suffers from an excess of significance. Overeager researchers often tinker too much with the statistical variables of their analysis to coax any meaningful insight from their data sets. "People are messing around with the data to find anything that seems significant, to show they have found something that is new and unusual," Dr. Ioannidis said.

Reciting the Litturgy

In a number of past posts over at Coyote Blog, I have noticed the phenomenon of published studies whose data does nothing to bolster the theory of anthropogenic global warming adding in a line or two in the article saying that "of course the author’s support anthorpogenic global warming theory" in the same way movies routinely assure audiences that "no animals were hurt in the filiming of this movie."

Here is one example:  If you have seen An Inconvinient Truth, then you may remember a Really Big Chart shown by Gore with 650,000 years of temperature history.  In case you missed it, here is the data, derived from ice cores:

The red line is CO2 concentrations, while the black line is a proxy for temperatures.  When it first came out, it was compelling evidence that CO2 was not only a major driver of temperature, it may be the main driver.  However, followup work showed that when you zoom in on the scale, the temperature in each spike starts rising 800 years before the CO2 rises, implying instead that temperature is driving CO2 (via outgassing from oceans) rather than the other way around.  Many call this problem the 800-year lag.  Anyway, the scientists who discovered this 800-year lag felt compelled to add this line to their publication.  They said the team

… is still in full agreement with the idea that CO2 plays, through its greenhouse effect, a key role in amplifying the initial orbital forcing …

You can just see the fear.  Please, don’t take our climate funding away.  We didn’t mean to find this evidence.  We’re sorry.  We’re still believers.  Another example here.

Anyway, this week Steven Milloy has an even more stark example:

Veizer reluctantly told me the "text" of the Nature study, that is, the above-quoted conclusion, represented a "compromise" between the study’s disagreeing authors where Veizer’s side apparently did all the compromising for reasons that had little to do with the science.

While Veizer didn’t want to elaborate on the politics of the Nature study, he told me "not to take the tone of the paper as the definitive last word."…

There’s another point worth spotlighting in all this. It seems that the politics of global warming including the multibillion-dollar-funding of global warming research resulted in the publication in a prestigious science journal of a "compromise" conclusion that is not supported by the study’s own data.

"Science should never be adjusted to fit policy," was the reprimand the U.S. Environmental Protection Agency received from its own Science Advisory Board in 1992. But that’s exactly what seems to be happening to climate science. It’s a situation reminiscent of George Orwell’s "1984," in which Ministry of Truth worker Winston Smith wonders if the State could get away with declaring that "two and two made five."

Who’s wondering now? A recent series of reports from the Science and Public Policy Institute spotlights problems with the peer review process of the United Nations Intergovernmental Panel on Climate Change (IPCC) and efforts to create the illusion of scientific consensus on global warming.

Grading US Temperature Measurement Sites

Anthony Watts has initiated a nationwide effort to photo-document the climate stations in the US Historical Climate Network (USHCN).  His database of documented sites continues to build at SurfaceStations.org.  Some of my experiences contributing to his effort are here and here.

Using criteria and a scoring system devised years ago based on the design specs of the USHCN and use in practice in France, he has scored the documented stations as follows, with 1 being a high-conforming site and 5 being a site with many local biaes and issues.  (Full criterea here)


Note that category 3-5 stations can be expected to exhibit errors from 1-5 degrees C, which is huge both because these stations make up 85% of the stations surveyed to date and because this error is so much greater than the "signal."  The signal we are trying to use the USHCN to detect is global warming, which over the last century is currently thought to be about 0.6C.  This means that the potential error may be 2-8 times larger than the signal.  And don’t expect these errors to cancel out.  Because of the nature of these measurement problems and biases, almost all of these errors tend to be in the same direction – biasing temperatures higher – creating a systematic error that does not cancel out.  Also note that though this may look bad, this situation is probably far better than the temperature measurement in the rest of the world, so things will only get worse when Anthony inevitably turns his attention overseas.

Yes, scientists try to correct for these errors, but so far they have done so statistically without actually inspecting the individual installations.  And Steve McIntyre is doing a lot of work right now demonstrating just how haphazard these measurement correction currently are, though there is some recent hope that things may improve.

Antarctic Sea Ice at Record High

It is almost impossible to avoid stories about Arctic sea at the lowest recorded level.  The National Geographic, who should know better, had the temerity to headline "Arctic Ice at All-Time Low".  All-time?  Really?  In the 6 billion year history of the earth, this is the least ice ever in the Arctic?  Well, no, it’s the least since we have started measuring it.  So when was that?  Only since about 1979 when we had sattelites that could make this measurement.  OK, so its the least ice in about 25-30 years.

To a one, scientists and media making this observation about Arctic sea ice use it as a leading indicator of catastrophic global warming.  The National Geographic even suggests it is evidence that we are at a tipping point, or a cusp of rapid acceleration of warming.

There is little doubt the Arctic has been warming the last 30 years or so, but some doubt whether it is warmer even than the 1940’s.  Be that as it may, last I checked there were two poles with sea ice.  It’s funny no one ever mentions the South Pole.  Do you think that they just forgot?  Or could it be that the facts don’t conviniently fit the storyline?  Luboš Motl picks up the story:

Some analysts have speculated that the new record could be evidence of global warming. But is it? Even though it may sound very complicated, it turns out that the Earth is round. At the global scale, there is not one polar region but, in fact, two. There is also sea ice on the Southern Hemisphere. It turns out that the Antarctic sea ice area reached 16.2 million squared kilometers in 2007 – a new absolute record high since the measurements started in 1979

The data is here:


If you watched An Inconvinient Truth, you will be saying, "this can’t be right."  In that movie, Al Gore and company showed compelling films of melting and warming in Antarctica.  Well, it turns out that most of Antarctica is seeing more snowfall and ice formation and the same or colder temperatures, but one small area, about 2% of the landmass on the Antarctic penninsula, is seeing warming.  Guess which area the movie chose to focus on? 

Even if the Antarctic were warming, most climate scientists expect snow and ice pack to increase there, not decrease.  Yes, warmer weather melts ice, but Antarctica is so freaking cold a few degrees are no more likely to melt ice than steel is to melt in the Arizona sunshine.  But warmer weather does vaporize more water, which is expected to fall as snowpack in Antarctica.  That is why despite Al Gore’s claims that oceans will rise 20 feet or more, serious scientists don’t expect much more than a foot, even with warming numbers far higher than I think are credible.  That’s because ice melting in Greenland and other glaciers is offset by increasing snow pack in Antarctica  (melting sea ice has no effect on ocean levels, since the ice floats, for the same reason that ice melting in your glass of water will not cause the glass to overflow).

By the way, since we are talking about retreating ice, here is a picture showing the retreat of the Glaciers at beautiful Glacier Bay, Alaska.Image054

So most of the retreat of the glaciers occured between 1794 and 1907, which is fairly hard to correlate with man’s use of fossil fuels or global CO2 levels.

USA Only 2% of Earth’s Surface, But…

Several weeks ago, NASA was forced to restate downwards recent US temperature numbers due to an error found by Steve McIntyre (and friends).  The restatement reinforced the finding that the US really has not had much warming over the last 100 years.  James Hansen, emporer of the NASA data for whom the rest of us are just "court jesters" dismissed both the restatement and the lack of warming trend in the US as irrelevent because the US only makes up about 2% of the world’s surface. 

This is a fairly facile statement, and Hansen has to know it.  Three quarters of the earth’s surface is water for which we have no real long term temperature record of any quality.  Large masses like Antarctica, South America, and Africa have very few places where temperature has been measured for any long period of time.  In fact, via Anthony Watts, here is the world map of temperature measurement points that have data for all of the 20th century (of whatever quality):


So the US is irrelevent, is it?  There is some danger in trying to eyeball such things, but I would say that the US is about one-half to one-third of the world’s landmass that has continuous temperature coverage.  I won’t get into this today, but for all the quality issues that have been identified in US measurements (particularly upwards urban biases) these problems are much greater in the rest of the world.

Further to Hansen’s point that the US does not matter, here is a quote from Hansen last week (emphasis added)

Another favorite target of those who would raise doubt about the reality of global warming is the lack of quality data from South America and Africa, a legitimate concern. You will note in our maps of temperature change some blotches in South America and Africa, which are probably due to bad data. Our procedure does not throw out data because it looks unrealistic, as that would be subjective. But what is the global significance of these regions of exceptionally poor data? As shown by Figure 1, omission of South America and Africa has only a tiny effect on the global temperature change. Indeed, the difference that omitting these areas makes is to increase the global temperature change by (an entirely insignificant) 0.01C.

Look at the map!  He is now saying that the US, South America, and Africa are irrelevent to world temperatures.  And with little ocean coverage and almost no coverage in Antarctica before 1960, what are we left with?  What does matter?  How is he weighting his temperature aggregations if none of these matter?  Fortunately, the code is finally in the open, so we may find out.

Why I Don’t Fear Catastrophic Warming (in Two Graphs)

Scientists have a concept called climate sensitivity which refers to the amount of global warming in degrees Celsius we might expect from a doubling of CO2 concentrations from a pre-industrial 280ppm to 560ppm  (we are currently at about 380ppm today and will reach 560ppm between 2065 and 2100, depending on how aggressive a forecast you want to adopt).

A simple way to estimate sensitivity is from experience over the past century.  At the same time CO2 has gone up by 100ppm, global temperatures have gone up by at most 0.6 Celsius (from the 4th IPCC report).  I actually believe this number is over-stated due to uncorrected urban effects and other surface temperature measurement issues, but let’s assume 0.6ºC.  Only a part of that 0.6ºC is due to man – some is likely do to natural cyclical effects, but again to avoid argument, let’s assume man’s CO2 has heated the earth 0.6 Celsius.  From these data points, we can project forward:


As you can see, the projection is actually a diminishing curve.  For reasons I will not go into again (you can read much more in this post) this relationship HAS to be a diminishing curve.  It’s a fact accepted by everyone.  True climate consensus.  We can argue about the slope and exact shape, but I have chosen midpoint values from a reasonable range.  The answer is not that sensitive to different assumptions anyway.  Even a linear extrapolation, which is clearly wrong scientifically, would only yield a sensitivity projection a few tenths of a degree higher.

What we arrive at is a sensitivity of about 1.2 degrees Celsius for a CO2 doubling (where the blue line crosses 560ppm).  In other words, we can expect another 0.6ºC increase over the next century, about the same amount we experienced (and most of us failed to notice) over the last century.

But, you are saying, global warming catastrophists get so much higher numbers.  Yes they do, with warming as high as 9-10C in the next century.  In fact, most global warming catastrophists believe the climate sensitivity is at least 3ºC per doubling, and many use estimates as high as 5ºC or 6ºC.  Do these numbers make sense?  Well, let’s draw the same curve for a sensitivity of 3ºC, the low end of the catastrophists’ estimates, this time in red:


To get a sensitivity of 3.0ºC, one has to assume that global warming due solely to man’s CO2 (nothing else) would have to be 1.5ºC to date (where the red line intersects the current concentration of 380ppm).  But no one, not the IPCC or anyone else, believes measured past warming has been anywhere near this high.  So to believe the catastrophic man-made global warming case, you have to accept a sensitivity three or more times higher than historical empirical data would support.  Rather than fighting against climate consensus, which is how we are so often portrayed, skeptics in fact have history and empirical data on our side.  For me, this second chart is the smoking gun of climate skepticism.  We have a lot of other issues — measurement biases, problems with historical reconstructions, role of the sun, etc — but this chart highlights the central problem — that catastrophic warming forecasts make no sense based on the last 100+ years of actual data.

Global warming catastrophists in fact have to argue against historical data, and say it is flawed in two ways:  First, they argue there are positive feedbacks in climate that will take hold in the future and accelerate warming; and second, they argue there are other anthropogenic effects, specifically sulphate aerosols, that are masking man-made warming.  Rather than just repeat myself (and in the interest in proving I can actually be succinct) I will point you to this post, the second half of which deals in depth with these two issues. 

As always, you can find my Layman’s Guide to Skepticism about Man-made Global Warming here.  It is available for free in HTML or pdf download, or you can order the printed book that I sell at cost.

A Good First Step: Hansen & GISS Release the Code

One of the bedrock principles of scientific inquiry is that when publishing results, one should also publish enough information about the experimental process so that others can attempt to replicate the results.  Bedrock principle everywhere, that is, except in climate science of course.  Climate researchers routinely refuse to release key aspects of their research that would allow others to replicate their findings — Mann’s refusal to release information about his famous "hockey stick" analysis even in the face of FOIA’s is just the most famous example.

A few weeks ago, after Steven McIntyre and a group of more-or-less amateurs discovered apparent issues in the NASA GISS temperature data, James Hansen and the GISS were forced to admit a programming error and restate some recent US temperatures (downwards).  As I wrote at Coyote Blog, the key outcome of this incident was not the magnitude of the restatement, but the presure it might put on Hansen to release the software code NASA uses to aggregate and adjust historical temperature measurements:

For years, Hansen’s group at GISS, as well as other leading climate scientists such as Mann and Briffa (creators of historical temperature reconstructions) have flaunted the rules of science by holding the details of their methodologies and algorithm’s secret, making full scrutiny impossible.  The best possible outcome of this incident will be if new pressure is brought to bear on these scientists to stop saying "trust me" and open their work to their peers for review.  This is particularly important for activities such as Hansen’s temperature data base at GISS.  While measurement of temperature would seem straight forward, in actual fact the signal to noise ration is really low.  Upward "adjustments" and fudge factors added by Hansen to the actual readings dwarf measured temperature increases, such that, for example, most reported warming in the US is actually from these adjustments, not measured increases.

I concluded:

NOAA and GISS both need to release their detailed algorithms and computer software code for adjusting and aggregating USHCN and global temperature data.  Period.  There can be no argument.  Folks at RealClimate.org who believe that all is well should be begging for this to happen to shut up the skeptics.  The only possible reason for not releasing this scientific information that was created by government employees with taxpayer money is if there is something to hide.

The good news is that Hansen has released what he claims to be the complete source code.  Hansen, with extraordinarily bad grace, has always claimed that he has told everyone all they need to know, and that it is other people’s fault if they can’t figure out what he is doing from his clear instructions.  But just read this post at Steve McIntyre’s site, and see the detective work that folks were having to go through trying to replicate NASA’s temperature adjustments without the code.

The great attention that Hansen has garnered for himself among the politically correct glitterati, far beyond what a government scientist might otherwise expect, seems to have blown his mind.  Of late, has has begun to act the little Caeser, calling his critic’s "court jesters," with the obvioius implication that he is the king.  Even in releasing the code he can’t resist a petulent swipe at his critics (emphasis added):

Reto Ruedy has organized into a single document, as well as practical on a short time scale, the programs that produce our global temperature analysis from publicly available data streams of temperature measurements. These are a combination of subroutines written over the past few decades by Sergej Lebedeff, Jay Glascoe, and Reto. Because the programs include a variety of
languages and computer unique functions, Reto would have preferred to have a week or two to combine these into a simpler more transparent structure, but because of a recent flood of demands for the programs, they are being made available as is. People interested in science may want to wait a week or two for a simplified version.

LOL.  The world is divided into two groups:  His critics, and those who are interested in science.

This should be a very interesting week.

Table of Contents: A Layman’s Guide to Man-Made Global Warming

The purpose of this paper is to provide a layman’s critique of the Anthropogenic Global Warming (AGW) theory, and in particular to challenge the fairly widespread notion that the science and projected consequences of AGW currently justify massive spending and government intervention into the world’s economies.  This paper will show that despite good evidence that global temperatures are rising and that CO2 can act as a greenhouse gas and help to warm the Earth, we are a long way from attributing all or much of current warming to man-made CO2.  We are even further away from being able to accurately project man’s impact on future climate, and it is a very debatable question whether interventions today to reduce CO2 emissions will substantially improve the world 50 or 100 years from now.

Update: If you would like to start with the 60-second version of this long paper, try here first.

Update #2: New!  This paper is a couple of years old.  I have gotten better (if I may say so myself) in formulating the arguments.  My most recent stab at a skeptic’s summary is embodied in this free video.  If you don’t have time for the video, the powerpoint presentation with all the slides from the lecture are included in both .ppt and .pdf formats.

Note you may click on any of the chapter links below to see the full chapter in HTML, or see below for links to free pdf versions available for download.

Table of Contents for A Layman’s Guide to Anthropogenic Global Warming (AGW)
Chapter 1: Summary of Global Warming Skeptics Position
Chapter 2:  Is It OK to be a Global Warming Skeptic?

  • Charges of Bias
  • The Climate Trojan Horse
  • The Need to Exaggerate

Chapter 3: The Basics of Anthropogenic Global Warming (AGW) Theory
Chapter 4:  The Historical Evidence for Man-Made Global Warming

  • The long view (650,000 years)
  • The medium view (1000 years)
  • The short view (100 years)
  • Sulfates, Aerosols and Dimming
  • The troposphere and Urban heat islands
  • Using Computer Models to Explain the Past

Chapter 5:  The Climate Computer Models and Predicting Future Temperatures

  • The Dangers in Modeling Complex Systems
  • Do Model Outputs Constitute Scientific Proof?
  • Econometrics and CO2 Forecasts
  • Climate Sensitivity and the Role of Positive Feedbacks
  • Climate Models have to be Aggressively Tweaked to Match History

Chapter 6:  Alternate Explanations and Models for Global Warming

  • Solar Irradiance
  • Cosmic Rays
  • Man’s Land Use

Chapter 7:  The Effects of Global Warming

  • Why only bad stuff?
  • Ice melting / Oceans Rising
  • Hurricanes & Tornadoes
  • Temperature Extremes
  • Extinction and Disease
  • Collapse of the Gulf Stream and Freezing of Europe
  • Non-warming Effects of CO2

Chapter 8:  Kyoto and Climate Change Policy Alternatives

  • Kyoto
  • Cost of the Solutions vs. the Benefits:  Why Warmer but Richer may be Better than Colder and Pooer

Chapter 9: Rebuttals by Man-Made Global Warming Theory Supporters

UPDATE: A video version of this guide called What is Normal?  A Critique of Catastrophic Man-Made Global Warming Theory is now available for free download.

A Youtube Playlist for the film is here.  This is a cool feature I have not used before, but will effectively let you run the parts end to end, making the 50-minute video more or less seamless.

The individual parts are:

Climate Video Part 1:  Introduction; how greenhouse gases work; historical climate reconstructions
Climate Video Part 2:  Historical reconstructions; problems with proxies
Climate Video part 3:  How much warming is due to man; measurement biases; natural cycles in climate
Climate Video Part 4:  Role of the sun; aerosols and cooling; climate sensitivity; checking forecasts against history
Climate Video Part 5:  Positive and negative feedback;  hurricanes.
Climate Video Part 6:  Melting ice and rising oceans; costs of CO2 abatement; conclusions.

You may also stream the entire climate film from Google Video here. (the video will stutter between the 12 and 17 second marks, and then should run fine)

You may download a 258MB full resolution Windows Media version of the film by right-clicking here.

You may download a 144MB full resolution Quicktime version of the film by right-clicking here.

A 9-minute version of the climate video can be found here.

For those interested in getting a copy of my A Skeptical Layman’s Guide to Anthropogenic Global Warming, I greatly encourage you to download it for free.  However, I do know that some folks have written about a print version.  I have a print version of my global warming book available now at LuLu.com. It is $16.98 — that is my cost — and I warn you that LuLu’s shipping options are not very cheap.  I will try to find a less expensive print option, but no one beats LuLu for getting a book set up quickly and easily for print-to-order.


The open comment thread for this paper can be found here.

Chapter 1: Summary of the Skeptical Layman’s Guide to Man-Made Global Warming

The table of contents for the rest of this paper, A Layman’s Guide to Anthropogenic Global Warming (AGW) is hereFree pdf of this Climate Skepticism paper is here and print version is sold at cost here.

We know the temperature of the Earth has increased over the last half of the 19th century and most of the 20th century as the world has exited a particularly cold period called the Little Ice Age.  One of the odd coincidences that colors our judgment about climate trends is that man began systematically measuring temperatures in the early to mid-nineteenth century just as the world was beginning to exit what was perhaps the coldest period of the last millennia.  Throughout their study of climate trends, scientists have to try to parse warming that is a natural result of exiting this cyclical cold period from warming that is perhaps due to man’s influence.

We know further, from laboratory work, that CO2, and more importantly water vapor, in the atmosphere serves to keep the Earth warmer than it would be in their absence.  What we don’t know, in fact what we have no empirical proof for, is if rising CO2 levels over the last century (caused in part by man’s combustion of fossil fuels) has caused some or all of the 20th century warming.  The fact that we have no empirical evidence for this man-made effect on climate doesn’t mean it is not true, but it is something we should not forget in all this debate.  What we have instead are historical correlations in the data, far from perfect, that seem to show some relationship over history between CO2 and temperature.  Some find this data to be compelling evidence of cause and effect, and others do not. 

Before we start, since this paper is by definition somewhat in opposition to the core of Anthropogenic Global Warming (AGW) theory, it would be useful to state in simple terms just what that theory is.   The strong AGW hypothesis is roughly as follows:

1. The world has been warming for a century, and this warming is beyond any cyclical variation we have seen over the last 1000 or more years, and beyond the range of what we might expect from natural climate variations.

2. Almost all of the warming in the second half of the 20th century, perhaps a half a degree Celsius, is due to man-made greenhouse gasses, particularly CO2

3. In the next 100 years, CO2 produced by man will cause a lot more warming, from as low as three degrees C to as high as 8 or 10 degrees C.

4. Positive feedbacks in the climate, like increased humidity, will act to triple the warming from CO2, leading to these higher forecasts and perhaps even a tipping point into climactic disaster

5. The bad effects of warming greatly outweigh the positive effects, and we are already seeing the front end of these bad effects today (polar bears dying, glaciers melting, etc)

6. These bad effects, or even a small risk of them, easily justify massive intervention today in reducing economic activity and greenhouse gas production

In the rest of this paper, we will focus on potential weaknesses in this hypothesis. Specifically, I will argue that:

There is no doubt that CO2 is a greenhouse gas, and it is pretty clear that CO2 produced by man has an incremental impact on warming the Earth’s surface. 

However, recent warming is the result of many natural and man-made factors, and it is extraordinarily difficult to assign all the blame for current warming to man. 

In turn, there are very good reasons to suspect that climate modelers may be greatly exaggerating future warming due to man.  Poor economic forecasting, faulty assumptions about past and current conditions, and a belief that climate is driven by runaway positive feedback effects all contribute to this exaggeration. 

As a result, warming due to man’s impacts over the next 100 years may well be closer to one degree C than the forecasted six to eight.  In either case, since AGW supporters tend to grossly underestimate the cost of CO2 abatement, particularly in lost wealth creation in poorer nations, there are good arguments that a warmer but richer world, where aggressive CO2 abatement is not pursued, may be the better end state than a poor but cooler world.

In Chapter 2, we will address whether it is even appropriate to be a skeptic.  Of late, several AGW supporters have declared the science “settled,” and skeptics the equivalent of tobacco lawyers or holocaust deniers.  We will also look at the issue of bias, not just for skeptics but for AGW supporters as well.

In Chapter 3, we will cover a bit of background on Anthropogenic Global Warming (AGW) theory.  We  will learn some things about the CO2 greenhouse effect you have probably never heard in the media, such as the fact that warming from CO2 is actually a diminishing return phenomenon whose effect is asymptotic or essentially capped, making it hard to understand the prevalence of wild, open-ended temperature runaway scenarios.

In Chapter 4, we will review the historic empirical evidence for AGW theory.  We will find that the science of historic climate reconstruction is still in its infancy, and a lot of uncertainty exists in the data.  We will see that over the last several years, while correlations between CO2 and temperature exist in the data, much of the historical circumstantial evidence for AGW theory has gotten weaker, and we will cover “global dimming” and see if this effect makes the case for AGW stronger.

In Chapter 5 we will cover the absolutely fascinating topic of climate models.  Most of what you have seen in the media is the output of complex climate models.  We will find that there is a lot less here than meets the eye.

In Chapter 6 we will study several alternate explanations for recent warming that don’t involve man-made greenhouse gasses.  Most prominent in these theories is the changing output of the sun.

In Chapter 7 we take on the scare stories – the lions and tigers and bears of climate reporting.  In the movie An Inconvenient Truth, Al Gore caught the world’s attention with prophecies of seas rising twenty feet, hurricanes and tornados running rampant, and species dying. We will find that most of these claims are thought to be wild exaggerations even by scientists who support AGW theory.

In Chapter 8 we finally get to the Kyoto Treaty, explain its origins and shortcomings, and briefly discuss some policy alternatives. We’ll seriously consider whether a cooler but poorer world is really superior to a warmer but richer world.

Finally, in Chapter 9, we will consider AGW supporter’s rebuttals of some of these arguments.  For this version, we will use the New Scientist’s recent 26 Global Warming Myths as a platform for this discussion.

My Goals For This Paper

The purpose of this paper is to provide a layman’s critique of the Anthropogenic Global Warming (AGW) theory, and in particular to challenge the fairly widespread notion that the science and projected consequences of AGW currently justify massive spending and government intervention into the world’s economies.  This paper will show that despite good evidence that global temperatures are rising and that CO2 can act as a greenhouse gas and help to warm the Earth, we are a long way from attributing all or much of current warming to man-made CO2.  We are even further away from being able to accurately project man’s impact on future climate, and it is a very debatable question whether interventions today to reduce CO2 emissions will substantially improve the world 50 or 100 years from now.

I am not a trained expert on the climate.  I studied physics at Princeton University before switching my major to mechanical engineering, where I specialized in control theory and feedback loops, a topic that will be important when we get into the details of climate change modeling.  For over ten years, my business specialty was market prediction and sales forecasting using modeling approaches similar to (if far less complex than) those used in climate.

My goal for this paper is not to materially advance climate science.  However, I have found that the global warming skeptic’s case is seldom reported well or in any depth, and I wanted to have a try at producing a fair reporting of the skeptic’s position.   I have been unhappy with several of the recent documentaries outlining the skeptic’s case, either because they skipped over a number of critical issues, or because they over-sold alternate warming hypotheses that are not yet well understood. To the inevitable charge that as a non-practitioner, I am not qualified to write this paper –I believe that I am able to present the current state of the science, with a particular emphasis on the skeptic’s case, at least as well as a good reporter might, and far better than most reporters actually portray the state of the science.  Through this paper I will try to cite sources as often as possible and provide links for those who are reading this online, this report is best read as journalism, not as a scientific, meticulously footnoted paper.

Years ago, another man not trained in climate started a PowerPoint presentation of what he knew about Global Warming.  Over time, he used it both as a vehicle for communication as well as a living document that would evolve over time to reflect his improving knowledge.  A lot of people saw Al Gore’s PowerPoint presentation, and it became the backbone for the movie An Inconvenient Truth.  I hope to use this paper the same way, as an evolving document to reflect my evolving knowledge.  To this end, each version will get a software-like version number and date.

Before proceeding, I want to make one note on nomenclature.  The terms global warming and climate change are often used interchangeably, and generally are used in a way that imply man-made causes.  For example, when many people speak of global warming, they are actually talking about anthropogenic global warming, meaning warming of the Earth from man-made causes, generally the release of greenhouse gasses including CO2.  Of course the climate can, and does, change without man’s help and the Earth can warm without man-made gasses.  I will try to be precise in my terminology.  I will use global warming to mean literally an increase in Earth’s surface temperatures, no matter what the cause.  I will use anthropogenic global warming, or AGW, to mean the theory that man is causing some or all of the current warming.

Finally, any abuse of copyrighted material or mistakes in attribution are entirely unintentional.  Such problems, as well as any comments, should be sent to the author at the email address on the cover.

The table of contents for the rest of this paper, A Layman’s Guide to Anthropogenic Global Warming (AGW) is hereFree pdf of this Climate Skepticism paper is here and print version is sold at cost here.

The open comment thread for this paper can be found here. 

Chapter 2 (Skeptics Guide to Global Warming): Is it OK to be a Skeptic?

The table of contents for the rest of this paper, A Layman’s Guide to Anthropogenic Global Warming (AGW) is hereFree pdf of this Climate Skepticism paper is here and print version is sold at cost here.

For the first time since the Catholic Church dominated western man’s affairs, it has suddenly become a sin again to be labeled a “skeptic.”  For most of my lifetime, “skepticism” was considered an essential element in the makeup of any good scientist (or journalist, for that matter).   However, leading world figures are declaring skepticism to be immoral.  Take one example, from this UPI story:

A former chief of the U.N. World Health Organization who also is a former prime minister of Norway and a medical doctor has declared an end to the climate-change debate.

Dr. Gro Harlem Brundtland, one of U.N. Secretary-General Ban Ki-moon’s three new special envoys on climate change, also headed up the 1987 U.N. World Commission on Environment and Development where the concept of sustainable development was first floated.

"This discussion is behind us. It’s over," she told reporters. "The diagnosis is clear, the science is unequivocal — it’s completely immoral, even, to question now, on the basis of what we know, the reports that are out, to question the issue and to question whether we need to move forward at a much stronger pace as humankind to address the issues."

In its most extreme form, this approach has AGW supporters labeling skeptics as equivalent to “holocaust deniers” and “tobacco lawyers.”  Efforts have been made in several quarters to decertify climatologists or meteorologists who show any skepticism for AGW theory, making public adherence to the theory a minimum qualification for publication and professional standing.  Enormous efforts are made to squelch skeptical speech.  Just as one example, the BBC has run a zillion shows and specials sympathetic to AGW.  When Channel 4 ran one single show (called the “Global Warming Swindle”) which outlined parts of the skeptics’ position, 37 scientists attempted to have it suppressed by the government.

This is all the more incredible given that AGW theory has only really been researched seriously and with any critical mass for about 20 years.  Anyone who has studied the history of science will understand what incredible hubris it is to declare any new scientific theory, particularly one that concerns the unbelievably chaotic climate, as “done” after just 20 years work. 

Let me give two quick examples of just how unsettled the science of climate change is.  Both of these will be reviewed in more depth later in this paper, and both analyses figured prominently in the third IPCC report (2001) as well as Al Gore’s An Inconvenient Truth.  The first is a 100,000 year temperature and CO2-level reconstruction from ice-core data.  Anyone who saw Gore’s movie will remember the data in one of his Really Big Charts.  And it looks compelling – in fact, when I first saw the chart five years ago, it was compelling to me.  It shows CO2 levels and temperature moving in lock-step for 100,000 years.  When CO2 is up, temperature is up and vice-versa, the clear implication being that CO2 seems to be a key, maybe the key, driver of climate   However, since that chart was first prepared, laboratory procedure has improved, and scientists have found (and there is very little disagreement about this, even among strong AGW supporters) that temperature increases occur on average 800 years before the CO2 starts to increase.  Huh.  There is a lot of debate about what this means, but in the last five years, this formerly definitive analysis is clearly no longer definitive, since it is hard to cause something after the fact.

The other example is the very famous Mann hockey stick chart, prominently featured in Gore’s movie and a key part of the IPCC report in 2001.  I will go into the details later, but since 2001 this analysis has been effectively discredited, so much so it was almost entirely missing from the fourth IPCC report in 2007.  In 2003 or so, Al Gore and many AGW supporters would have called the Mann hockey stick chart the single most important analysis “proving” AGW, and Gore treated it as such in his PowerPoint deck and his movie.  Then, in 2007, it is repudiated and expunged from the record.  Is this really what any reasonable person would call a “settled” science?

It is a true perversion of the scientific process to find that skepticism is no longer welcome or accepted in scientific debate. Which is one reason that AGW is sometimes called a secular religion. Because it is religion, not science, that burns skeptics at the stake.  Climate Scientists Garth Paltridge wrote:

A colleague of mine put it rather well. The IPCC, he said, has developed a highly successful immune system. Its climate scientists have become the equivalent of white blood cells which rush in overwhelming numbers to repel infection by ideas and results which do not support the basic thesis that global warming is perhaps the greatest of the modern threats to mankind.

Charges of Bias

A funny thing has happened in climate science to scientific inquiry: the usual ethics of free discussion and fact-based criticism have been discarded in favor of ad hominem attacks on critics of AGW theory. The usual approach is to find some connection (even an imagined one) between any researcher who raises the smallest doubts about AGW theory and an oil or power company and then declare that the research is tainted by the bias of these companies that have a strong economic reliance on fossil fuel combustion (and thus the production of CO2).  A good example can be found in a Boston Globe article on MIT’s Alfred P. Sloan professor of meteorology Richard Lindzen.  Mr. Lindzen has become the bete noir of AGW supporters, since his skepticism is harder to dismiss given his scientific pedigree and his co-lead author status on the first IPCC climate change report.

"We do not understand the natural internal variability of climate change" is one of Lindzen’s many heresies, along with such zingers as `"the Arctic was as warm or warmer in 1940," "the evidence so far suggests that the Greenland ice sheet is actually growing on average," and "Alpine glaciers have been retreating since the early 19th century, and were advancing for several centuries before that. Since about 1970, many of the glaciers have stopped retreating and some are now advancing again. And, frankly, we don’t know why."

When Lindzen published similar views in The Wall Street Journal this spring, environmentalist Laurie David, the wife of comedian Larry David, immediately branded him a "shill." She resurrected a shopworn slur first directed against Lindzen by former Globe writer Ross Gelbspan, who called Lindzen a "hood ornament" for the fossil fuels industry in a 1995 article in Harper’s Magazine….

For no apparent reason, the state of California, Environmental Defense, and the Natural Resources Defense Council have dragged Lindzen and about 15 other global- warming skeptics into a lawsuit over auto- emissions standards. California et al. have asked the auto companies to cough up any and all communications they have had with Lindzen and his colleagues, whose research has been cited in court documents.

"We know that General Motors has been paying for this fake science exactly as the tobacco companies did," says ED attorney Jim Marston. If Marston has a scintilla of evidence that Lindzen has been trafficking in fake science, he should present it to the MIT provost’s office. Otherwise, he should shut up.

"This is the criminalization of opposition to global warming," says Lindzen, who adds he has never communicated with the auto companies involved in the lawsuit.

While I have no doubt that corporations are heavily influenced by their own economic interests, it is more of stretch to argue that anyone who has ever taken money from them or had any connection with them would purposely bias their research.  When I learned to debate, I was taught that understanding biases was useful in knowing when to apply more or less skepticism, but one still has to refute the opposing position by meaningful critique of procedures or data.   For example, one might say “given their strong desire to buttress the case for AGW, the researchers cherry-picked only the most extreme data, which I will demonstrate by showing the data they included and the data they chose to exclude.”  However, many modern AGW supporters believe that insinuating possible sources of bias is sufficient to exempt one from having to actually critique their opponents’ methods and findings. 

This is particularly odd given that public funding for AGW projects absolutely dwarfs any funding coming from private sources whose incentive might be to disprove AGW.  In fact, just this year, President Bush declared that the US Government alone spent more money on AGW research than on AIDS research, and the US is actually late in the climate funding game. 

Recently, Greenpeace criticized ExxonMobil for exercising its free speech rights and giving about $2 million to global warming skeptics

Still, the Greenpeace report is already receiving scrutiny in Washington, where Rep. Brad Miller, a North Carolina Democrat, has joined the environmentalist group in calling for Exxon to release its plans for contributions during the current year.

"The support of climate skeptics, many of whom have no real grounding in climate science, appears to be an effort to distort public discussion about global warming," Miller said. "So long as popular discussion could be about whether warming was occurring or not, so long as doubt was widespread, consensus for action could be postponed."

Incredibly, at these spending rates, skeptics are getting outspent by AGW supporters something like 1000:1 or more.  It is astounding that AGW supporters, with such a huge funding and publication advantage, still feel threatened by critics.

Climate research, once a sleepy academic backwater, is now a multi-billion dollar industry.  This boom in spending is because of fears of AGW, and should AGW theory be discredited, this funding will quickly dry up.  So funding for climate researchers exists only as long as climate researchers beat the drum that AGW is a large threat.   It strikes me that this is at least as large an incentive for bias as that of any Exxon-funded skeptic.   Here’s another way to look at it:  If AGW theory is proven correct, the likely political response might cut Shell’s revenues by 20-30%, at most.  If AGW theory is proven incorrect, then university climate research funding might be cut by 100%.   Directionally, all the incentives in academia are to inflate global warming projections.  No one is going to make the news, or even continue to get funding, if they argue that warming will only be a degree or two in the next century.  The guys that get the fame and the grants are those pushing the numbers higher and higher.

Certainly AGW supporters claim that academic researchers are only concerned about the science and are not concerned about the funding incentives.  This may be true (though a bit naïve, for anyone who has been in a university environment and sought research funding), but if pro-AGW researchers are not swayed by the funding, then it should be equally true that AGW skeptics are not swayed by much smaller amounts of money flowing to them.    Any argument that tries to claim that these situations are somehow different just ends up being circular, i.e. “it’s OK if our guys do it because our guys are right.”

One of the mistakes the IPCC process has systematically made is to make the lead author’s and reviewers of many of its report sections a scientist whose research is mostly in that area.  While this makes a certain sense, as these people will be expert in their particular area of review, it presents them with a huge conflict of interest.  For example, Michael Mann used his own historical temperature reconstructions as the lead analysis in the section of the third IPCC report for which he was lead author.  Clearly, one wouldn’t expect him to be (nor was he) open to any research or issues or criticisms aimed at his own work.  In the fourth report, the new lead author who replaced Mann on this section (Biffra) did the exact same thing Mann did – used his own work as centerpiece of the section, and has refused to even consider criticisms about that work. 

Just to avoid future argument, I will outline my potential biases.  I own a small recreation business which depends on people traveling to beautiful, natural settings.  I lose business when the climate changes (e.g. when lakes dry up next to my facilities, which has happened to me).  I generally gain business when gas prices increase, as they might under various anti-global warming mandates, since my facilities tend to be short-drive weekend destinations rather than cross-country destinations.  I grew up in Houston, Texas, so most of my family has worked in the oil industry at one time or another, and I worked for the Great Satan Exxon as my first job for three years out of college.  I am a libertarian blogger at CoyoteBlog.com, and am suspicious of government interventions but have historically supported emissions limits where they make sense.  No one has contributed any money to me for this paper or for the operation of my blog.

The Climate Trojan Horse

To fully understand the passionate, almost dogmatic dedication so many people have to AGW theory, it is a bit useful to look at a little history.  After the fall of the Soviet Union in 1989, there were a lot of Marxists, socialists, anti-corporatists and anti-capitalists who were looking for a new way to package and reinvent themselves, given that the vast majority of people (at least in the West) considered socialism failed and no longer wanted to hear about it any more.  For a while, many of these folks latched onto the anti-globalization cause.  Every interview I ever saw of one of these anti-globalization guys was a real mess of disorganized beliefs, but one could tell the movement was the new home for anyone who wanted to stop the spread of capitalism and privately-owned business. 

Then, along came anthropogenic global warming.  Here was a theory and movement that united many disparate interests:

  • Socialists, communists, and Marxists
  • Anti-capitalists
  • Anti-consumerists
  • Those opposed to large corporations
  • Those opposed to global free trade
  • Those opposed to economic development and growth, longing      for simplicity
  • “Buy local” movements
  • People who just hate oil companies

Suddenly, here was a big tent for all of these causes. I highly encourage you to view a global warming rally.  Don’t just watch the snippets on the evening news, those usually highlight the most reasonable speakers at the rally.  Actually go and watch the whole event.  What you will see is far more anti-corporate, anti-oil company, anti-capitalist rhetoric than you will hear climate science and discussion.  The two rallies I have seen with my own eyes were Marxist rallies under a climate banner.  As an admittedly extreme example, I will refer you to the words of Paul Watson, Founder and President of Sea Shepherd Conservation Society, who offers his group’s vision.  While this particular vision pre-dated most discussions of AGW, I hope you can see how AGW fear-mongering provides quite a useful vehicle for groups of this type:

"We need to radically and intelligently reduce human populations to fewer than one billion…. We need to stop burning fossil fuels and utilize only wind, water, and solar power with all generation of power coming from individual or small community units like windmills, waterwheels, and solar panels. Sea transportation should be by sail…. Air transportation should be by solar powered blimps when air transportation is necessary. All consumption should be local. No food products need to be transported over hundreds of miles to market. All commercial fishing should be abolished. If local communities need to fish the fish should be caught individually by hand. Preferably vegan and vegetarian diets can be adopted…. We need to remove and destroy all fences and barriers that bar wildlife from moving freely across the land…. We need to stop flying, stop driving cars, and jetting around on marine recreational vehicles…. Who should have children? Those who are responsible and completely dedicated to the responsibility which is actually a very small percentage of humans…."

Of course what he doesn’t say, but is an explicit outcome of this vision, is that we can all go back to being dirt poor and having a life expectancy of about 40 years.

The average person, say in America, wants little to do with any of this.  But fear of AGW provides a way to engage everyone in the movement.  Socialists of all stripes no longer have to spew Marxist notions that turn most people off; now, they can talk the science of global warming and hurricanes and massive floods and such, and, using fear, trample the average guy into their socialist goals of stifling capitalism, growth, and having the government take over the economy through this environmental back-door.

The Need to Exaggerate

One of the hardest parts of really trying to understand what is going on in the AGW scientific debate is separating the scientists doing real science from the political advocates, who sometimes carry quasi-scientific titles.  A very, very small number of vocal climate scientists and a somewhat larger group of what I would call advocates and bureaucrats really determine what you hear in the media about AGW science.   A great example is the UN IPCC reports.  Unless you have gone online and dug into the detailed reports themselves, likely all you have seen from these reports is taken out of the management summaries “for policy-makers”.  These summaries are written by bureaucrats and advocates, not so much by scientists, and tend to wildly mis-characterize the true state of the science.   Careful language in the heart of the reports expressing uncertainty and low understanding of certain phenomena are cast aside in the summaries, in favor of a comforting certainty and absolutes.  In earlier IPCC reports, this caused notable disconnects between the summaries and the detailed science.  More recently, the UN has “fixed” this problem by having their non-scientists write the conclusions in the management summaries first, and then telling authors of the individual sections of the report to conform their writing, and their science, to the summary.  So, for the Fourth IPCC report, the summary was published over a half year before the science!

As a result, while the IPCC reports claim to be the consensus of 5000 scientists, actually less than half would willingly sign their name to the management summaries of their work that you see in the press.  The management summaries and related press releases have become more political advocacy than science, as UN bureaucrats use AGW-fear-mongering to increase their prestige and power.  Generally, these summaries and press releases are taken more seriously by the press than they are climate scientists. You can get an insight on the IPCC process just by looking at how they select their co-lead authors on certain sections.  A logical way to choose these authors would be to find scientists who bring a different scientific perspective – maybe a leading astronomer who studies the sun, maybe someone who studies hurricanes, or perhaps even, gasp, a skeptic or two.  This is not how the IPCC makes the selection.  Instead, they focus on including scientists, often with limited experience or expertise, who bring geographic or ethnic diversity to the panel.  Nothing better demonstrates that the IPCC is first and foremost a political entity, and a scientific body second (at best).

If I seem too hard on the climate science community, then consider this quote from National Center for Atmospheric Research (NOAA) climate researcher and global warming action promoter, Steven Schneider:

We have to offer up scary scenarios, make simplified, dramatic statements, and make little mention of any doubts we have. Each of us has to decide what the right balance is between being effective and being honest.

Is that how you learned science in high school – that lying about the science was OK if it makes you more politically effective?  Der Spiegel, a magazine historically sympathetic to the AGW cause, published this analysis:

This doesn’t mean that Gore should necessarily be taken to task for his statements. He is a politician. But it is odd to hear IPCC Chairman Pachauri, when asked what he thinks about Gore’s film, responding: "I liked it. It does emotionalize the debate, but it seems that it has to do that." And when Pachauri comments on the publication of the first SPM by saying, "I hope that this will shock the governments so much that they take action," this doesn’t exactly allay doubts as to his objectivity. When Renate Christ, the secretary of the IPCC, is asked about her opinion of reporting on climate change, she refers to articles that mention "climate catastrophe" and calls them "rather refreshing." . . .

The problem is that the IPCC is not a political group whose goal is to exert pressure, but a scientific institution and panel of experts. Its members ought to present their results and analyses dispassionately, the way pathologists or psychiatrists do when serving as expert witnesses in court, no matter how horrible the victim’s injuries and how deviant the perpetrator’s psyche are.

I will end this section on an admittedly extreme example of a headline taken from the Canadian, a “progressive” magazine up in the Great White North.  In the great race to one-up other media outlets in creating a panic, and not happy with just a few more hurricanes or some melted icebergs, the Canadian has taken the prize.  Get ready for it…

"Over 4.5 Billion people could die from Global Warming-related causes by 2012"

In case you are struggling with the math, that means that they believe Global Warming could kill three quarters of the world’s population in the next five years.  And the media treats these people with total respect, and we skeptics are considered loony?

The table of contents for the rest of this paper, A Layman’s Guide to Anthropogenic Global Warming (AGW) is hereFree pdf of this Climate Skepticism paper is here and print version is sold at cost here.

The open comment thread for this paper can be found here. 

Chapter 3 (Skeptics Guide to Global Warming): The Basics of Anthropogenic Global Warming Theory

The table of contents for the rest of this paper, A Layman’s Guide to Anthropogenic Global Warming (AGW) is hereFree pdf of this Climate Skepticism paper is here and print version is sold at cost here.

I will not even try do full justice here to the basic theory of AGW theory.  I highly encourage you to check out RealClimate.org.  This is probably the premier site of strong AGW believers and I really would hate to see AGW skeptics become like 9/11 conspiracists, spending their time only on like-minded sites in some weird echo chamber. 

If you are reading this, you probably know that CO2 is what is called a greenhouse gas.  This means that it can temporarily absorb radiation from the Earth, slowing its return to space and thereby heating the troposphere (the lower 10KM of the atmosphere) which in turn can heat up the Earth’s surface.  You probably also know that CO2 is not the only greenhouse gas, and that water vapor, for example, is actually a much stronger and more prevalent greenhouse gas.   

It is important to understand that the greenhouse gas effect is well-understood in the laboratory.  No one really disagrees that, all other effects held constant in a laboratory, CO2 will absorb certain wavelengths of reflected sunlight.   What may or may not be well-understood, depending on your point of view, is how this translates to the actual conditions in our chaotic climate.  Does this effect dominate all other climate effects, or is it trivial compared to other forces at work? Does this greenhouse effect lead to runaway, accelerating change, or are there opposing forces that tend to bring the climate back in balance?  These are hugely complex questions, and scientists are a long way from answering them empirically.

But wait, that can’t be right — scientists seem so sure!  Well, some scientists, particularly those close to microphones, seem sure.  Their proof usually follows one or both of these paths:

  1. Some scientists argue that they believe they have accounted for all the potential natural causes, or “forcings,” in the climate that might cause the warming we have observed over the last century, and they believe these natural forcings are not enough to explain recent temperature increases, so therefore the changes must be due to man. This seems logical, until I restate their logic this way:  “the warming must be due to man because we can’t think of anything else it could be.” 
  2. Scientists have created complicated models to predict future climate behavior.  They argue that their models show man-made CO2 causing most 20th century warming.  Again this sounds good, until one understands that when these models were first run, they were terrible at explaining history.  Since these first runs, scientists have tweaked the models until they match historical data better.  So, in effect, they are saying that manmade CO2 is the cause of historical warming because the models they tweaked to match history… are very good at matching history; and because the models they programmed with CO2 as the major driver of climate show that…CO2 is the major driver of climate.  We will see a lot of such circular analysis in later chapters.

The best evidence we could expect to find (lacking a second identical Earth we can use as a control in an experiment) is to find a historic correlation between temperature and CO2 that is stronger than the correlation between temperature and anything else (and of course, even this would not imply causation).  There is a lot of argument whether we have that or not, a topic I will cover in the next chapter.  Of course, the lack of unequivocal evidence at this point does not make the AGW theory wrong, just still… theoretical.   

Before we get to the historical evidence, though, there may be a few other facts about CO2 and warming that you don’t know:

  • CO2 is a really, really small part of the atmosphere. Currently CO2 makes up about 0.0378% of the atmosphere, up from an estimated 0.0280% before the industrial revolution.  (Just to give an      idea of scale, if you were flying from Los Angeles to New York City, traveling 0.0378% of the distance would not even get you off the runway at LAX.  AGW advocates are arguing that a CO2 concentration increase of 0.009% has heated the world over a half a degree C.
  • The maximum warming should, by greenhouse gas theories, occur in the troposphere (the first 10km or so of atmosphere). Global warming theory strongly predicts that the warming in the      troposphere should be higher than warming at the ground.  We will see later that the opposite is actually occurring.
  • The radiated energy returning to space consists of a wide spectrum of wavelengths.  Only a few of these wavelengths are absorbed by CO2.  Once these few wavelengths are fully absorbed,      additional CO2 in the atmosphere has no effect whatsoever.  Also, these absorbed frequencies overlap with the absorption of other gasses, like water, which further lessens the incremental effect of extra CO2.

What does this mean?  In effect, the warming effect of CO2 is a diminishing return relationship. The first increase of, say, 100 parts per million (ppm) in the atmosphere has a greater effect than the next 100 ppm, and so on until increased CO2 has essentially no effect at all. 

I once bought a house that had fuchsia walls in the kitchen and family room (really).  I spent all night painting the rooms with a coat of white paint, and when I was done, I found that some of the  fuchsia still showed through the white paint, making it kind of light pink.  A second coat of white made the wall nearly perfectly white.  The effects of CO2 in the atmosphere are similar, with the first “coat” making for the most warming and later “coats” having much less effect but still adding a bit.  At some point, the wall is white and more coats have no effect. 

This relationship of CO2 to warming is usually called sensitivity, and is often expressed as the number of degrees of global warming that would result from a doubling in global CO2 concentrations.

There are lots of values floating around out there for sensitivity, but a preponderance (I won’t say consensus) seem to center on an increase of one degree C for a doubling of CO2 levels from the pre-industrial figure of about 280ppm.  Note that you will see numbers much higher than this, but these generally include feedback loops, which we will get to later.  Without feedbacks, 0.5 to maybe 1.5 degrees seems like a fairly well accepted number for sensitivity, though there are people on both side of this range.

Luboš Motl provides a handy approximation of the diminishing return effect from CO2 concentration on temperature.  I have taken his approximation and graphed it below.

This is a very crude approximation, but the shape of the curve is generally correct (if you exclude feedbacks, which we will discuss in MUCH more depth later).   Other more sophisticated approximations generally show the initial curve less steep, and the asymptote less pronounced.  Never-the-less, it is generally accepted by most all climate scientists that, in the absence of feedbacks, future increases in atmospheric CO2 will have less effect on world temperature than past increases, and that there is a cap (in this chart around 1.5 degrees C) on the total potential warming.

Note that this is much smaller than you will see in print.  The key is in “feedbacks” or secondary effects that accelerate or slow warming.  We will discuss these in more depth later, but typically AGW supporters believe these will triple the sensitivity numbers, so a non-feedback sensitivity of one degree would be tripled to three degrees.  Remember, though, these three points:

· Warming from CO2 is a diminishing return, such that future CO2 increases has less effect than past CO2 increases

· In the absence of feedback, a doubling of CO2 might increase temperatures one degree C

· In the absence of feedback, the total temperature increase from future CO2 increases is capped, maybe as low as 1-1.5 degrees C.

The table of contents for the rest of this paper, A Layman’s Guide to Anthropogenic Global Warming (AGW) is hereFree pdf of this Climate Skepticism paper is here and print version is sold at cost here.

The open comment thread for this paper can be found here.

Chapter 4 (Skeptics Guide to Global Warming): The Historical Evidence for Man-made Global Warming

The table of contents for the rest of this paper, A Layman’s Guide to Anthropogenic Global Warming (AGW) is hereFree pdf of this Climate Skepticism paper is here and print version is sold at cost here.

I mentioned earlier that there is little or no empirical evidence directly linking increasing CO2 to the current temperature changes in the Earth (at least outside of the lab), and even less, if that is possible, linking man’s contribution to CO2 levels to global warming.  It is important to note that this lack of empirical data is not at all fatal to the theory.  For example, there is a thriving portion of the physics community developing string theory in great detail, without any empirical evidence whatsoever that it is a correct representation of reality. Of course, it is a bit difficult to call a theory with no empirical proof “settled” and, again using the example of string theory, no one in the physics community would seriously call string theory a settled debate, despite the fact it has been raging at least twice as long as the AGW debate.

One problem is that AGW is a fairly difficult proposition to test.  For example, we don’t have two Earths such that we could use one as the control and one as the experiment.  Beyond laboratory tests, which have only limited usefulness in explaining the enormously complex global climate, most of the attempts to develop empirical evidence have involved trying to develop and correlate historical CO2 and temperature records. If such records could be developed, then temperatures could be tested against CO2 and other potential drivers to find correlations.  While there is always a danger of finding false causation in correlations, a strong historical temperature-CO2 correlation would certainly increase our confidence in AGW theory. 

Five to seven years ago, climate scientists thought they had found two such smoking guns:  one in ice core data going back 650,000 years, and one in Mann’s hockey stick using temperature proxy data going back 1,000 years.  In the last several years, substantial issues have arisen with both of these analyses, though this did not stop Al Gore from using both in his 2006 film.

Remember what we said early on.  The basic “proof” of anthropogenic global warming theory outside the laboratory is that CO2 rises have at least a loose correlation with warming, and that scientists “can’t think of anything else” that might be causing warming other than CO2.

The long view (650,000 years)

When I first saw it years ago, I thought one of the more compelling charts from Al Gore’s PowerPoint deck, which was made into the movie An Inconvenient Truth, was the six-hundred thousand year close relationship between atmospheric CO2 levels and global temperature, as discovered in ice core analysis.  Here is Al Gore with one of those great Really Big Charts.

If you are connected to the internet, you can watch this segment of Gore’s movie at YouTube.   I will confess that this segment is incredibly powerful — I mean, what kind of Luddite could argue with this Really Big Chart?

Because it is hard to read in the movie, here is the data set that Mr. Gore is drawing from, taken from page 24 of the recent fourth IPCC report.

Unfortunately, things are a bit more complicated than presented by Mr. Gore and the IPCC.  In fact, Gore is really, really careful how he narrates this piece.  That is because, by the time this movie was made, scientists had been able to study the ice core data a bit more carefully.  When they first measured the data, their time resolution was pretty course, so the two lines looked to move together.  However, with better laboratory procedure, the ice core analysts began to find something funny.  It turns out that for any time they looked at in the ice core record, temperatures actually increased on average 800 years before CO2 started to increase. When event B occurs after event A, it is really hard to argue that B caused A.

So what is really going on?  Well, it turns out that most of the world’s CO2 is actually not in the atmosphere, it is dissolved in the oceans.  When global temperatures increase, the oceans give up some of their CO2, outgassing it into the atmosphere and increasing atmospheric concentrations.  Most climate scientists today (including AGW supporters) agree that some external force (the sun, changes in the Earth’s tilt and rotation, etc) caused an initial temperature increase at the beginning of the temperature spikes above, which was then followed by an increase in atmospheric CO2 as the oceans heat up.

What scientists don’t agree on is what happens next. Skeptics tend to argue that whatever caused the initial temperature increase drives the whole cycle.  So, for example, if the sun caused the initial temperature increase, it also drove the rest of the increase in that cycle.  Strong AGW supporters on the other hand argue that while the sun may have caused the initial temperature spike and outgassing of CO2 from the oceans, further temperature increases were caused by the increases in CO2.

The AGW supporters may or may not be right about this two-step approach.   However, as you can see, the 800-year lag substantially undercuts the ice core data as empirical proof that CO2 is the main driver of global temperatures, and completely disproves the hypothesis that CO2 is the only key driver of global temperatures.  We will return to this 800-year lag and these two competing explanations later when we discuss feedback loops.

The medium view (1000 years)

Until about 2000, the dominant reconstruction of the last 1000 years of global temperatures was similar to that shown in this chart from the 1990 IPCC report:


There are two particularly noticeable features on this chart.  The first is what is called the “Medieval Warm Period”, peaking in the 13th century, and thought (at least 10 years ago) to be warmer than our climate today.  The second is the “Little Ice Age” which ended at about the beginning of the industrial revolution.  Climate scientists built this reconstruction with a series of “proxies”, including tree rings and ice core samples, which (they hope) exhibit properties that are strongly correlated with historical temperatures.

However, unlike the 650,000 year construction, scientists have another confirmatory source for this period: written history. Historical records (at least in Europe) clearly show that the Middle Ages was unusually warm, with long growing seasons and generally rich harvests (someone apparently forgot to tell Medieval farmers that they should have smaller crops in warmer weather).  In Greenland, we know that Viking farmers settled in what was a much warmer period in Greenland than we have today (thus the oddly inappropriate name for the island) and were eventually driven out by falling temperatures.  There are even clearer historical records for the Little Ice Age, including accounts of the Thames in London and the canals in Amsterdam freezing on an annual basis, something that happened seldom before or since.

Of course, these historical records are imperfect.  For example, our written history for this period only covers a small percentage of the world’s land mass, and land only covers a small percentage of the world’s surface.  Proxies, however have similar problems.  For example, tree rings only can come from a few trees that cover only a small part of the Earth’s surface.  After all, it is not every day you bump into a tree that is a thousand years old (and that anyone will let you cut down to look at the rings).  In addition, tree ring growth can be covariant with more than just temperature (e.g. precipitation);  in fact, as we continue to study tree rings, we actually find tree ring growth diverging from values we might expect given current temperatures (more on this in a bit).

Strong AGW supporters found the 1990 IPCC temperature reconstruction shown above awkward for their cause.  First, it seemed to indicate that current higher temperatures were not unprecedented, and even coincided with times of relative prosperity.  Further, it seems to show that global temperatures fluctuate widely and frequently, thus begging the question whether current warming is just a natural variation, an expected increase emerging from the Little Ice Age.

So along comes strong AGW proponent (and RealClimate.org founder) Michael Mann of the University of Massachusetts.  Mann electrified the climate world, and really the world as a whole, with his revised temperature reconstruction, shown below, and called “the Hockey Stick.”


Gone was the Little Ice Age.  Gone was the Medieval Warm Period.  His new reconstruction shows a remarkably stable, slightly downward trending temperature record that leaps upward in 1900.  Looking at this chart, who could but doubt that our current global climate experience was something unusual and unprecedented.  It is easy to look at this chart and say – wow, that must be man-made!

In fact, the hockey stick chart was used by AGW supporters in just this way.  Surely, after a period of stable temperatures, the 20th century jump is an anomaly that seems to point its finger at man (though if one stops the chart at 1950, before the period of AGW, the chart, interestingly, is still a hockey stick, though with only natural causes).

Based on this analysis, Mann famously declared that the 1990’s were the warmest decade in a millennia and that "there is a 95 to 99% certainty that 1998 was the hottest year in the last one thousand years." (By the way, Mann now denies he ever made this claim, though you can watch him say these exact words in the CBC documentary Global Warming:  Doomsday Called Off).   If this is not hubris enough, the USAToday published a graphic, based on Mann’s analysis and which is still online as of this writing, which purports to show the world’s temperature within .0001 degree for every year going back two thousand years!

To reconcile historical written records with this new view of climate history, AGW supporters argue that the Medieval Warm Period (MWP) was limited only to Europe and the North Atlantic (e.g. Greenland) and in fact the rest of the world may not have been warmer. Ice core analyses have in fact verified a MWP in Greenland, but show no MWP in Antarctica (though, as I will show later, Antarctica is not warming yet in the current warm period, so perhaps Antarctic ice samples are not such good evidence of global warming).  AGW supporters, then, argue that our prior belief in a MWP was based on written records that are by necessity geographically narrowly focused.  Of course, climate proxy records are not necessarily much better.  For example, from the fourth IPCC report, page 55, here are the locations of proxies used to reconstruct temperatures in AD1000:

As seems to be usual in these reconstructions, there were a lot of arguments among scientists about the proxies Mann used, and, just as important, chose not to use.  I won’t get into all that except to say that many other climate archaeologists did not and do not agree with his choice of proxies and still support the existence of a Little Ice Age and a Medieval Warm Period. There also may be systematic errors in the use of these proxies which I will get to in a minute. 

But some of Mann’s worst failings were in the realm of statistical methodology.  Even as a layman, I was immediately able to see a problem with the hockey stick:  it shows a severe discontinuity or inflection point at the exact same point that the data source switches between two different data sets (i.e.  from proxies to direct measurement).  This is quite problematic.   Syun-Ichi Akasofu makes the observation that when you don’t try to splice these two data sets together, and just look at one (in this case, proxies from Arctic ice core data as well as actual Arctic temperature measurements) the result is that the 20th century warming in fact appears to be part of a 250 year linear trend, a natural recovery from the little ice age  (the scaling for the ice core data at top is a chemical composition variable thought to be proportional to temperature).

However, the real bombshell was dropped on Mann’s work by a couple of Canadian scientists named Stephen McIntyre and Ross McKitrick (M&M). M&M had to fight an uphill battle, because Mann resisted their third party review of his analysis at every turn, and tried to deny them access to his data and methodology, an absolutely unconscionable violation of the principles of science (particularly publicly funded science).  M&M got very good at filing Freedom of Information Act Requests (or the Canadian equivalent)

Eventually, M&M found massive flaws with Mann’s statistical approach, flaws that have since been confirmed by many experts, such that there are few people today that treat Mann’s analysis seriously (At best, his supporters defend his work with a mantra roughly akin to “fake but accurate.”  I’ll quote the MIT Technology Review for M&M’s key finding:

But now a shock: Canadian scientists Stephen McIntyre and Ross McKitrick have uncovered a fundamental mathematical flaw in the computer program that was used to produce the hockey stick. …

[Mann’s] improper normalization procedure tends to emphasize any data that do have the hockey stick shape, and to suppress all data that do not. To demonstrate this effect, McIntyre and McKitrick created some meaningless test data that had, on average, no trends. This method of generating random data is called Monte Carlo analysis, after the famous casino, and it is widely used in statistical analysis to test procedures. When McIntyre and McKitrick fed these random data into the Mann procedure, out popped a hockey stick shape!

A more complete description of problems with Mann hockey stick can be found at this link.  Recently, a US Congressional Committee asked a group of independent statisticians led by Dr. Edward Wegman, Chair of the National Science Foundation’s Statistical Sciences Committee, to evaluate the Mann methodology.  Wegman et. al. savaged the Mann methodology as well as the peer review process within the climate community.  From their findings:

It is important to note the isolation of the paleoclimate community; even though they rely heavily on statistical methods they do not seem to be interacting with the statistical community. Additionally, we judge that the sharing of research materials, data and results was haphazardly and grudgingly done. In this case we judge that there was too much reliance on peer review, which was not necessarily independent. Moreover, the work has been sufficiently politicized that this community can hardly reassess their public positions without losing credibility. Overall, our committee believes that Dr. Mann’s assessments that the decade of the 1990s was the hottest decade of the millennium and that 1998 was the hottest year of the millennium cannot be supported by his analysis.

In 2007, the IPCC released its new climate report, and the hockey stick, which was the centerpiece bombshell of the 2001 report, and which was the “consensus” reconstruction of this “settled” science, can hardly be found.  There is nothing wrong with errors in science; in fact, science is sometimes advanced the most when mistakes are realized.  What is worrying is the unwillingness by the IPCC to acknowledge a mistake was made, and to try to learn from that mistake.  Certainly the issues raised with the hockey stick are not mentioned in the most recent IPCC report, and an opportunity to be a bit introspective on methodology is missed.  M&M, who were ripped to shreds by the global warming community for daring to question the hockey stick, are never explicitly vindicated in the report.  The climate community slunk away rather than acknowledging error.

In response to the problems with the Mann analysis, the IPCC has worked to rebuild confidence in its original conclusion (i.e. that recent years are the hottest in a millennium) using the same approach it often does:  When one line on the graph does not work, use twelve: 

As you can see, most of these newer analyses actually outdo Mann by showing current warming to be even more pronounced than in the past (Mann is the green line near the top).  This is not an unusual phenomenon in global warming, as new teams try to outdo each other (for fame and funding) in the AGW sales sweepstakes.  Just as you can tell the newest climate models by which ones forecast the most warming, one can find the most recent historical reconstructions by which ones show the coldest past. 

Where to start?  Well, first, we have the same problem here that we have in Mann:  Recent data from an entirely different data set (the black line) has been grafted onto the end of proxy data.  Always be suspicious of inflection points in graphs that occur exactly where the data source has changed.  Without the black line from an entirely different data set grafted on, the data would not form a hockey stick, or show anything particularly anomalous about the 20th century.  Notice also a little trick, by the way – observe how far the “direct measurement” line has been extended.  Compare this to the actual temperatures in the charts above.  The authors have taken the liberty to extend the line at least 0.2 degrees past where it actually should be to make the chart look more dramatic.

There are, however, some skeptics conclusions that can be teased out of this data, and which the IPCC completely ignores.  For example, as more recent studies have deepened the little ice age around 1600-1700, the concurrent temperature recovery is steeper (e.g. Hegerl 2007 and Moberg 2005) such that without the graft of the black line, these proxies make the 20th century look like part of the fairly linear temperature increase since 1700 or at least 1800.

But wait, without that black line grafted on, it looks like the proxies actually level off in the 20th century!  In fact, from the proxy data alone, it looks like the 20th century is nearly flat.  In fact, this effect would have been even more dramatic if lead author Briffa hadn’t taken extraordinary liberties with the data in his study.   Briffa (who replaced Mann as the lead author on this section for the Fourth Report) in 2001 initially showed proxy-based temperatures falling in the last half of the 20th century until he dropped out a bunch of data points by truncating the line around 1950.  Steve McIntyre has reconstructed the original Briffa analysis below without the truncation (pink line is measured temperatures, green line is Briffa’s proxy data).  Oops.

Note that this ability to just drop out data that does not fit is NOT a luxury studies have in the era before the temperature record existed.  By the way, if you are wondering if I am being fair to Briffa, here is his explanation for why he truncated:

In the absence of a substantiated explanation for the decline, we make the assumption that it is likely to be a response to some kind of recent anthropogenic forcing. On the basis of this assumption, the pre-twentieth century part of the reconstructions can be considered to be free from similar events and thus accurately represent past temperature variability.

Did you get that?  “Likely to be a response to some kind of recent anthropogenic forcing.”  Of course, he does not know what that forcing on his tree rings is and can’t prove this statement, but he throws the data out none-the-less.  This is the editor and lead author for the historical section of the IPCC report, who clearly has anthropogenic effects on the brain.  Later studies avoided Briffa’s problem by cherry-picking data sets to avoid the same result.

We’ll get back to this issue of the proxies diverging from measured temperatures in the moment.  But let’s take a step back and ask “So should 12 studies telling the same story (at least once they are truncated and “corrected’) make us more confident in the answer?”  It is at this point that it is worth making a brief mention of the concept of “systematic error.”   Imagine the problem of timing a race.  If one feared that any individual might make a mistake in timing the race, he could get say three people to time the race simultaneously, and average the results. Then, if in a given race, one person was a bit slow or fast on the button, his error might be averaged out with the other two for a result hopefully closer to the correct number.  However, let’s say that all three are using the same type of watch and this type watch always runs slow.  In this case, no amount of extra observers are going to make the answer any better – all the times will be too low.  This latter type of error is called systematic error, and is an error that, due to some aspect of a shared approach or equipment or data set, multiple people studying the same problem can end up with the same error.

There are a couple of basic approaches that all of these studies share.  For example, they all rely heavily on the same tree ring proxies (in fact the same fifty or sixty trees), most of which are of one species (bristlecone pine).  Scientists look at a proxy, such as tree rings, and measure some dimension for each year.  In this case, they look at the tree growth.  They compile this growth over hundreds of years, and get a data set that looks like 1999- .016mm, 1998, .018mm  etc.  But how does that correlate to temperature? What they do is pick a period, something like 1960-1990, and look at the data and say “we know temperatures average X from 1980 to 1990.  Since the tree rings grew Y, then we will use a scaling factor of X/Y to convert our 1000 years of tree ring data to temperatures. 

I can think of about a million problems with this. First and foremost, you have to assume that temperature is the ONLY driver for the variation in tree rings.  Drought, changes in the sun, changing soil composition or chemistry,  and even CO2 concentration substantially affect the growth of trees, making it virtually impossible to separate out temperature from other environmental effects in the proxy.

Second, one is forced to assume that the scaling  of the proxy is both linear and constant.  For example, one has to assume a change from, say, 25 to 26 degrees has the same relative effect on the proxy as a change from 30 to 31 degrees.  And one has to assume that this scaling is unchanged over a millennium.  And if one doesn’t assume the scaling is linear, then one has the order-of-magnitude harder problem of deriving the long-term shape of the curve from only a decade or two of data.  For a thousand years, one is forced to extrapolate this scaling factor from just one or two percent of the period.

But here is the problem, and a potential source for systematic error affecting all of these studies:  Current proxy data is wildly undershooting prediction of temperatures over the last 10-20 years.  In fact, as we learned above, the proxy data actually shows little or no 20th century warming.  Scientists call this “divergence” of the proxy data.  If Briffa had hadn’t artificially truncated his data at 1950, the effect would be even more dramatic.  Below is a magnification of the spaghetti chart from above – remember the black line is “actual,” the other lines are the proxy studies.







In my mind, divergence is quite damning.  It implies that scaling derived from 1960-1980 can’t even hold up for the next decade, much less going back 1000 years!  And if proxy data today can be undershooting actual temperatures (by a wide margin) then it implies it could certainly be undershooting reality 700 years ago.  And recognize that I am not saying one of these studies is undershooting – they almost ALL are undershooting, meaning they may share the same systematic error.  (It could also mean that measured surface temperatures are biased high, which we will address a bit later.

The short view (100 years)

The IPCC reports that since 1900, the world’s surface has warmed about 0.6C, a figure most folks will accept (with some provisos I’ll get to in a minute about temperature measurement biases).  From the NOAA Global Time Series:


This is actually about the same data in the Mann hockey stick chart — it only looks less frightening here (or more frightening in Mann) due to the miracle of scaling.  Next, we can overlay CO2:


This chart is a real head-scratcher for scientists trying to prove a causal relationship between CO2 and global temperatures.  By theory, temperature increases from CO2 should be immediate, though the oceans provide a big thermal sink that to this day is not fully understood. However, from 1880 to 1910, temperatures declined despite a 15ppm increase in CO2.  Then, from 1910 to 1940 there was another 15ppm increase in CO2 and temperatures rose about 0.3 degrees.  Then, from 1940-1979, CO2 increased by 30 ppm while temperatures declined again.  Then, from 1980 to present, CO2 increased by 40 ppm and temperatures rose substantially.  By grossly dividing these 125 years into these four periods, we see two long periods totaling 70 years where CO2 increases but temperature declines and two long periods totaling 55 years of both CO2 and temperature increases. 

By no means does this variation disprove a causal relation between CO2 concentrations and global temperature.  However, it also can be said that this chart is by no means a slam dunk testament to such a relationship.  Here is how strong AGW supporters explain this data: Strong AGW supporters will assign most, but not all, of the temperature increase before 1950 to “natural” or non-anthropogenic causes.  The current IPCC report in turn assigns a high probability that much or all of the warming after 1950 is due to anthropogenic sources, i.e. man-made CO2.  Which still leaves the cooling between 1940 and 1979 to explain, which we will cover shortly.

Take this chart from the fourth IPCC report (the blue band is what the IPCC thinks would have happened without anthropogenic effects, the pink band is their models’ output with man’s influence, and the black line is actual temperatures (greatly smoothed).

Scientists know that “something” caused the pre-1950 warming, and that something probably was natural, but they are not sure exactly what it was, except perhaps a recovery from the little ice age.  This is of course really no answer at all, meaning that this is just something we don’t yet know.  Which raises the dilemma: if whatever natural effects were driving temperatures up until 1950 cannot be explained, then how can anyone say with confidence that this mystery effect just stops after 1950, conveniently at the exact same time anthropogenic warming “takes over”?  As you see here, it is assumed that without anthropogenic effects, the IPCC thinks the world would have cooled after 1950.  Why?  They can’t say.  In fact, I will show later that this assumption is really just a necessary plug to prevent their models from overestimating historic warming.  There is good evidence that the sun has been increasing its output and would have warmed the world, man or no man, after 1950. 

But for now, I leave you with the question – If we don’t know what natural forcing caused the early century warming, then how can we say with confidence it stopped after 1950?  (By the way, for those of you who already know about global cooling/dimming and aerosols, I will just say for now that these effects cannot be making the blue line go down because the IPCC considers these anthropogenic effects, and therefore in the pink band. For those who have no idea what I am talking about, more in a bit).

Climate scientist Syun-Ichi Akasofu of the International Arctic Research Center at University of Alaska Fairbanks makes a similar point, and highlights the early 20th century temperature rise:

Again, what drove the Arctic warming up through 1940? And what confidence do we have that this forcing magically went away and has nothing to do with recent temperature rises?

Sulfates, Aerosols, and Dimming

Strong AGW advocates are not content to say that CO2 is one factor among many driving climate change.  They want to be able to say CO2 is THE factor.  To do so with the historical record over the last 100 years means they need to explain why the world cooled rather than warmed from 1940-1979.

Strong AGW supporters would prefer to forget the global cooling hysteria in the 1970s.  During that time, the media played up scientific concerns that the world was actually cooling, potentially re-entering an ice age, and that crop failures and starvation would ensue.  (It is interesting that AGW proponents also predict agricultural disasters due to warming.  I guess this means that we are, by great coincidence, currently at the exact perfect world temperature for maximizing agricultural output, since either cooling or warming would hurt production).  But even if they want to forget the all-too-familiar hysteria, they still need to explain the cooling.

What AGW supporters need is some kind of climate effect that served to reduce temperatures starting in 1940 and that went away around 1980.  Such an effect may actually exist.

There is a simple experiment that meteorologists have run for years in many places around the world.  They take a pan of water of known volume and surface area and put it outside, and observe how long it takes for the water to evaporate.  If one correctly adjusts the figures to reflect changes in temperature and humidity, the resulting evaporation rate should be related to the amount of solar irradiance reaching the pan.  In running these experiments, there does seem to be a reduction of solar irradiance reaching the Earth, perhaps by as much as 4% since 1950.  The leading hypothesis is that this dimming is from combustion products including sulfates and particulate matter, though at this point this is more of a hypothesis than demonstrated cause and effect.  The effect is often called “global dimming.”

The aerosol hypothesis is that sulfate aerosols and black carbon are the main cause of global dimming, as they tend to act to cool the Earth by reflecting and scattering sunlight before it reaches the ground.  In addition, it is hypothesized that these aerosols as well as particulates from combustion may act to seed cloud formation in a way that makes clouds more reflective.  The nations of the world are taking on sulfate and particulate production, and will likely substantially reduce this production long before CO2 production is reduced (mainly because it is possible with current technology to burn fossil fuels with greatly reduced sulfate output, but it is not possible to burn fossil fuels with greatly reduced CO2 output).  If so, we might actually see an upward acceleration in temperatures if aerosols are really the cause of dimming, since their removal would allow a sort-of warming catch-up.

Sulfates do seem to be a pretty good fit with the cooling period, but a couple of things cause the fit to be well short of perfect. First, according to Stern, production of these aerosols worldwide (right) did not peak until 1990, at level almost 20% higher than they were in the late 1970’s when the global cooling phenomena ended. 

One can also observe that sulfate production has not fallen that much, due to new contributions from China and India and other developing nations (interestingly, early drafts of the fourth IPCC report hypothesized that sulfate production may not have decreased at all from its peak, due to uncertainties in Asian production).  Even today, sulfate levels have not fallen much below where they were in the late 1960’s, at the height of the global cooling phenomena, and higher than most of the period from 1940 to 1979 where their production is used to explain the lack of warming.

Further, because they are short-lived, these sulfate dimming effects really only can be expected to operate over in a few isolated areas around land-based industrial areas, limiting their effect on global temperatures since they effect only a quarter or so of the globe.   You can see this below, where high sulfate aerosol concentrations, show in orange and red, only cover a small percentage of the globe.

Sulfate2 Given these areas, for the whole world to be cooled 1 degree C by aerosols and black carbon, the areas in orange and red would have to cool 15 or 20C, which absolutely no one has observed.  In fact, since as you can see, most of these aerosols are in the norther hemisphere, one would expect that, if cooling were a big deal, the northern hemisphere would have cooled vs. the southern, but in fact as we will see in a minute exactly the opposite is true — the northern hemisphere is heating much faster than the south.  Research has shown that dimming is three times greater in urban areas close to where the sulfates are produced (and where most university evaporation experiments are conducted) than in rural areas, and that in fact when you get out of the northern latitudes where industrial society dominates, the effect may actually reverse in the tropics.

There are, though, other potential explanations for dimming.  For example, dimming may be an effect of global warming itself.  As I will discuss in the section on feedback processes later, most well-regulated natural systems have feedback mechanisms that tend to keep trends in key variables from “running away.”  In this case, warming may be causing cloud formation due to increased evaporation from warmer oceans.

It is also not a done deal that test evaporation from pans necessarily represents the rate of terrestrial evaporation.  In fact, research has shown that pan evaporation can decrease because surrounding evaporation increases, making the pan evaporation more an effect of atmospheric water budgets and contents than irradiance.

This is a very important area for research, but as with other areas where promoters of AGW want something to be true, beware what you hear in the media about the science.  The IPCC’s fourth report continues to say that scientific understanding of many of these dimming issues is “low.”  Note also that global dimming does not “prove” AGW by any means, it merely makes the temperature-CO2 correlation better in the last half of the 20th century.  All the other issues we have discussed remain.

The Troposphere Dilemma and Urban heat islands

While global dimming may be causing us to under-estimate the amount of global warming, other effects may be causing us to over-estimate it.  One of the mysteries in climate science today has to do with different rates of warming on the Earth’s surface and in the troposphere (the first 10km or so of atmosphere above the ground).  AGW theory is pretty clear – the additional heat that is absorbed by CO2 is added to the troposphere, so the troposphere should experience the most warming from greenhouse gasses.  Some but not all of this warming will transfer to the surface, such that we should expect temperature increases from AGW to be larger in the troposphere than at the surface.

Well, it turns out that we have two ways to measure temperature in the troposphere.  For decades, weather balloons have been sent aloft to take temperature readings at various heights in the atmosphere.  Since the early 70’s, we have also had satellites capable of mapping temperatures in the troposphere.  From Spencer and Christy, who have done the hard work stitching the satellite data into a global picture, comes this chart of satellite-measured temperatures in the troposphere. The top chart is Global, the middle is the Northern Hemisphere, the bottom is the Southern Hemisphere

You will probably note a couple of interesting things. The first is that while the Northern hemisphere has apparently warmed about a half degree over the last 20 years, the Southern hemisphere has not warmed at all, at least in the troposphere.  You might assume this is because the Northern Hemisphere produces most of the man-made CO2, but scientists have found that there is very good global mixing in the atmosphere, and CO2 concentrations are about the same wherever you measure them.  Part of the explanation is probably due to the fact that temperatures are more stable in the Southern hemisphere (since land heats and cools faster than ocean, and there is much more ocean in the southern half of the globe), but the surface temperature records do not show such a north-south differential.  At the end of the day, nothing in AGW adequately explains this phenomenon.  (As an aside, remember that AGW supporters write off the Medieval Warm Period because it was merely a local phenomena in the Northern Hemisphere not observed in the south – can’t we apply the same logic to the late 20th century based on this satellite data?)

An even more important problem is that the global temperature increases shown here in the troposphere over the last several decades have been lower than on the ground, exactly opposite of predictions by AGW theory,

In 2006, David Pratt put together a combined chart of temperature anomalies, comparing satellite measurements of the troposphere with ground temperature measurements.  He found, as shown in the chart below, but as you can see for yourself visually in the satellite data, that surface warming is substantially higher over the last 25 years than warming of the troposphere.  In fact, the measured anomaly by satellite (and by balloon, as we will see in a minute) is half or less than the measured anomaly at the surface.

There are a couple of possible explanations for this inconsistency.  One, of course, is that there is something other than CO2-driven AGW that is at least partially driving recent global temperature increases.  We will cover several such possibilities in a later chapter on alternative theories.  One theory that probably does not explain this differential is global dimming.  If anything, global dimming should work the other way, cooling the ground vs. the troposphere.  Also, since CO2 works globally but SO2 dims locally, one would expect more cooling effect in the northern vs. the southern hemisphere, while actually the opposite is observed.


Another possible explanation, of course, is that one or the other of these data sets has a measurement problem.  Take the satellite data.  The measurement of global temperatures from space is a relatively new art, and the scientists who compile the data set have been through a number of iterations to their model for rolling the measurements into a reliable global temperature (Christy just released version 6).  Changes over the past years have actually increased some of the satellite measurements (the difference between ground and surface used to be even greater).  However, it is unlikely that the quality of satellite measurement is the entire reason for the difference for the simple reason that troposphere measurement by radiosonde weather balloons, a much older art, has reached very consistent findings (if anything, they show even less temperature  increase since 1979).

A more likely explanation than troposphere measurement problems is a measurement problem in the surface data.  Surface data is measured at thousands of points, with instruments of varying types managed by different authorities with varying standards.  For years, temperature measurements have necessarily been located on land and usually near urban areas in the northern hemisphere.  We have greatly increased this network over time, but the changing mix of reporting stations adds its own complexity.

The most serious problem with land temperature data is from urban heat islands.  Cities tend to heat their environment.  Black asphalt absorbs heat, concrete covers vegetation, cars and power sources produce heat.  The net effect is that a city is several degrees hotter than its surroundings, an effect entirely different from AGW, and this effect tends to increase over time as the city gets larger.   (Graphic courtesy of Bruce Hall)

Climate scientists sometimes (GISS – yes, NOAA — no) attempt to correct measurements in urban areas for this effect, but this can be chancy since the correction factors need to change over time, and no one really knows exactly how large the factors need to be.   Some argue that the land-based temperature set is biased too high, and some of the global warming shown is in fact a result of the UHI effect.   

Anthony Watts has done some great work surveying the problems with long-term temperature measurement (some of which was obtained for this paper via Steve McIntyre’s Climate Audit blog). He has been collecting pictures of California measurement sites near his home, and trying to correlate urban building around the measurement point with past temperature trends.  More importantly, he has created an online database at SurfaceStations.org where these photos are being put online for all researchers to access.

The tennis courts and nearby condos were built in 1980, just as temperature measurement here began going up.  Here is another, in Marysville, CA, surrounded by asphalt and right next to where cars park with hot radiators.  Air conditioners vent hot air right near the thermometer, and you can see reflective glass and a cell tower that reflect heat on the unit.  Oh, and the BBQ the firemen here use 3 times a week.

So how much of this warming is from the addition of air conditioning exhaust, asphalt paving, a nearby building, and car radiators, and how much is due to CO2.  No one knows.  The more amazing thing is that AGW supporters haven’t even tried to answer this question for each station, and don’t even seem to care. 

As of June 28, 2007, The SurfaceStations.org documentation effort received a setback when the NOAA, upon learning of this effort, removed surface station location information from their web site. The only conclusion is that the NOAA did not want the shameful condition of some of these sites to be publicized. 

I have seen sites like RealClimate arguing in their myth busting segments that the global temperature models are based only on rural measurements.  First, this can’t be, because most rural areas did not have measurement in the early 20th century, and many once-rural areas are now urban.  Also, this would leave out huge swaths of the northern hemisphere.  And while scientists do try to do this in the US and Europe (with questionable success, as evidenced by the pictures above of sites that are supposedly “rural”), it is a hopeless and impossible task in the rest of the world.  There just was not any rural temperature measurement in China in 1910.

Intriguingly, Gavin Schmidt, a lead researcher at NASA’s GISS, wrote Anthony Watts that criticism of the quality of these individual temperature station measurements was irrelevant because GISS climate data does not relay on individual station data, it relies on grid cell data.  Just as background, the GISS has divided the world into grid cells, like a matrix (example below).

Unless I am missing something fundamental, this is an incredibly disingenuous answer.  OK, the GISS data and climate models use grid cell data, but this grid cell data is derived from ground measurement stations.  So just because there is a statistical processing step between “station data” and “grid cell data” does not mean that at its core, all the climate models don’t rely on station data.  All of these issues would be easier to check of course if NASA’s GISS, a publicly funded research organization, would publicly release the actual temperature data it uses and the specific details of the algorithms it uses to generate and smooth and correct grid cell data.  But, like most all of climate science, they don’t.  Because they don’t want people poking into it and criticizing it.  Just incredible.

As a final note, for those that think something as seemingly simple as consistent temperature measurement is easy, check out this theory courtesy of Anthony Watts

It seems that weather stations shelters known as Stevenson Screens (the white chicken coop like boxes on stilts housing thermometers outdoors) were originally painted with whitewash, which is a lime based paint, and reflective of infra-red radiation, but its no longer available, and newer paints have been used that [have] much different IR characteristics.

Why is this important? Well, paints that appear "white" and reflective in visible light have different properties in infrared. Some paints can even appear nearly "black" and absorb a LOT of infrared, and thus bias the thermometer. So the repainting of thousands of Stevenson screens worldwide with paints of uncertain infrared characteristics was another bias that has crept into the instrumental temperature records.

After running this test, Watts actually ran an experiment comparing wood that had been whitewashed vs. using modern white latex paint.  The whitewashed wood was 5 degrees cooler than the modern latex painted wood.

Using Computer Models to Explain the Past

It is often argued by AGW supporters that because the historic warming is so close to what the current global warming models say historic temperatures should look like, and because the models are driven by CO2 forcings, then CO2 must be causing the historic temperature increase. We are going to spend a lot of time with models in the next chapter, but here are a few thoughts to tide us over on this issue.

The implication here is that scientists carefully crafted the models based on scientific theory and then ran the models, which nearly precisely duplicated history.  Wrong.  In fact, when the models were first built, scientists did exactly this.  And what they got looked nothing like history.

So they tweaked and tuned, changing a constant here, adding an effect (like sulfates) there, changing assumptions about natural forcings, until the models matched history.  The models match history because they were fiddled with until they matched history.  The models say CO2 caused warming because they were built on the assumption that CO2 causes warming.  So, unless one wants to make an incredibly circular argument, the models are useless in determining how much CO2 affects history.  But we’ll get to a lot more on models in the next chapter.

The table of contents for the rest of this paper, A Layman’s Guide to Anthropogenic Global Warming (AGW) is hereFree pdf of this Climate Skepticism paper is here and print version is sold at cost here.

The open comment thread for this paper can be found here. 

Chapter 5 (Skeptics Guide to Global Warming): Computer Models and Predicting Future Climate

The table of contents for the rest of this paper, A Layman’s Guide to Anthropogenic Global Warming (AGW) is hereFree pdf of this Climate Skepticism paper is here and print version is sold at cost here.

We have gotten well into this paper, and we still have not discussed what is perhaps the most problematic aspect of AGW research: the computer models.

If an economist came up with a computer model that he claimed could predict the market value of every house in the world in the year 2106 within $1,000, would you believe him?  No, you would say he was nuts — there is way too much uncertainty and complexity.  Climate, of course, is not the same as housing prices.  It is in fact, much, much more complex and more difficult to predict.  There is nothing wrong with trying to predict the complex and chaotic.  But there is a certain sense of hubris in believing that one has succeeded with the kind of 95% certainty figures used by the IPCC.

All climate forecasting models are created by a pretty insular and incestuous climate science community that seems to compete to see who can come up with the most dire forecast.  Certainly there are financial incentives to be as aggressive as possible in forecasting climate change, since funding dollars tend to get channeled to those who are the most dramatic. The global warming community spends a lot of time with ad hominem attacks on skeptics, usually accusing them of being in the pay of oil and power companies, but they all know that their own funding in turn would dry up rapidly if they were to show any bit of skepticism in their own work.

The details of these models is beyond the scope of this paper. However, it is important to understand how they work in broad outlines.

The modelers begin with certain assumptions about climate that they build into the model.  For example, the computers themselves don’t somehow decide if CO2 is a more important forcing on the climate than solar activity – the modelers, by the assumptions the feed into the model, decide these things.  The models return the result that CO2 is the most important driver of climate in the coming century because their programmers built them with that assumption, not because the model somehow sorts through different inputs and comes up with the key drivers on its own.

Because the models have been built to test man’s possible impact on the climate via greenhouse gas emissions, they begin with an econometric forecast of world economic growth, and, based upon assumptions about fuel sources and efficiencies, they convert this economic growth into emissions forecasts. The models generally contain subroutines that calculate, again based upon a variety of assumptions, how man-made CO2 plus other inputs will change the atmospheric CO2 concentration.  Then, via assumptions about climate sensitivity to CO2 and various feedback loops programmed in, the models will create forecasts of temperatures, precipitation, etc.  These models, depending on their complexity, will show regional variations in many of these variables.  Finally, the models are tuned so that they better match history, in theory making them more accurate for the future.

One should note that while the IPCC asked modelers to look at a series of different cases, the only substantial difference between these cases is the volume of CO2 and other greenhouse gasses produced.  In other words, the only sensitivity the IPCC seriously modeled was on levels of CO2.  No other contingency – e.g. potential variations in global temperature sensitivity to CO2, solar output, land use – were considered.  This should give you an idea of how hard-wired the anthropogenic causation is in the IPCC process.

In this section, I will begin by discussing the models’ basic assumptions about the climate.  I will then discuss the econometric forecasts they are founded on, the assumptions about CO2 sensitivity and feedback processes, and finally model tuning and their ability to match history.

The Dangers in Modeling Complex Systems

At any one time, thousands of people are being paid literally millions of dollars on Wall Street to try to model the behavior of various stock indices and commodity prices.  The total brain power and money power thrown over the last 50 years at trying to build an accurate predictive model for financial markets literally dwarfs, by a factor of 100 or more, the cumulative resources spent to date on long-term climate modeling.  Financial markets are incredibly complex, and they are driven by hundreds of variables. Interest rates, corporate profits, loan default rates, mortgage refinance rates, real estate prices, GDP growth, exchange rates, etc. all tend to drive the behavior of financial markets.  And no one has cracked the code. Sure, some people have built successful short-term trading models, but people have mostly lost their shirts when they have tried to make long-term bets based on computer financial models that beautifully matched history but failed to accurately predict the future.

How is it possible that a model that accurately represents the past fails to accurately predict the future?  Financial modelers, like climate modelers, look to history in building their models.  Again, like climate modelers, they rely both on theory (e.g. higher interest rates should generally mean lower stock prices) as well as observed correlations in the historic data set.  The problem they meet, the problem that every modeler meets but most especially the climate modeler, is that while it is easy to use various analysis tools to find correlations in the data, there is often nothing that will tell you if there is really a causal relationship, and which way the causality runs. For example, one might observe that interest rates and exchange rates move together.  Are interest rate changes leading to exchange rate adjustments, or vice versa?  Or, in fact, are they both caused by a third variable?  Or is their observed correlation merely coincidence?

It was once observed that if an old AFL football team wins the Superbowl, a bear market will ensue on Wall Street in the next year, while an NFL team victory presaged a bull market.  As of 1997, this correlation held for 28 of the last 31 years, a far better prediction record than that of any Wall Street analyst.  But of course this correlation was spurious, and in the next 4 years it was wrong every time.  Had someone built a financial model on this indicator, it would have looked great when he ran it against history, but he would have lost his shirt using it. 

Want a better prediction record?  For seventeen straight US presidential election cycles, from 1936 to 2000, the winner of the election was accurately predicted by…the Washington Redskins.  In particular, if the Redskins won their last home game before the election, the party that occupies the White House holds it in the election.  Otherwise, if the Redskins lose, the opposition party wins.  Seventeen in a row!  R-squared of one!  Success against odds of 131,072:1 of guessing all 17 right. But of course, the input was spurious, and in 2004, soon after this relationship made the rounds of the Internet, the algorithm failed.

This is why we spent so much time in the previous chapter on evaluating historic correlations between CO2 and temperature.  Because the models are built on an assumption that not only is temperature strongly correlated with CO2, but that temperature is historically highly stable without this outside anthropogenic forcing.  If there are problems with this assumed causation, which we saw there are, then there in turn are major inherent problems with the models themselves.   As climate scientist Syun-Ichi Akasofu of the International Arctic Research Center at University of Alaska Fairbanks wrote:

The computers are “taught” that the temperature rise during the last hundred years is due mostly to the greenhouse effect. If the truth is that only about 10% of the present warming is caused by the greenhouse effect, the computer code must be rewritten

Do Model Outputs Constitute Scientific Proof?

Remember what I said earlier:  The models produce the result that there will be a lot of anthropogenic global warming in the future because they are programmed to reach this result.  In the media, the models are used as a sort of scientific money laundering scheme.  In money laundering, cash from illegal origins (such as smuggling narcotics) is fed into a business that then repays the money back to the criminal as a salary or consulting fee or some other type of seemingly legitimate transaction.  The money he gets back is exactly the same money, but instead of just appearing out of nowhere, it now has a paper-trail and appears more legitimate.  The money has been laundered.

In the same way, assumptions of dubious quality or certainty that presuppose AGW beyond the bounds of anything we have see historically are plugged into the models, and, shazam, the models say that there will be a lot of anthropogenic global warming.  These dubious assumptions, which are pulled out of thin air, are laundered by being passed through these complex black boxes we call climate models and suddenly the results are somehow scientific proof of AGW.  The quality hasn’t changed, but the paper trail looks better, at least in the press.  The assumptions begin as guesses of dubious quality and come out laundered at “settled science.”  Climate Scientists Garth Paltridge wrote:

It needs to be understood that any reasonable simulation even of present climate requires computer models to be tuned. They contain parameters (that is, pieces of input information) whose numerical values are selected primarily to give the right answer about today’s climate rather than because of some actual measurement. This was particularly so in the mid-eighties. The problem with tuning is that it makes any prediction of conditions different from those of the present far less believable. Even today the disease of "tuneable parameters" is still rampant in climate models, although fairly well hidden and not much spoken of in polite society. The scientifically-inclined reader might try sometime asking a climate researcher just how many such parameters there are in his or her latest model. The reader will find there are apparently lots of reasons why such a question is ridiculous, or if not ridiculous then irrelevant, and if not irrelevant then unimportant. Certainly the enquirer will come away having been made to feel foolish.

Econometrics and CO2 Forecasts

The IPCC has never been able to choose a particular climate model it thinks is best.  Instead, it aggregates ten or twelve of them and averages their results, hoping that if there are errors in the climate models, they will average out somehow (forgetting that systematic errors don’t average out, as we discussed earlier in the context of historic temperature reconstructions).  The one thing the IPCC does do to bring some order to all this is to establish baseline econometric and emissions scenarios for all the teams to feed into the front end of their models.  That way, for a given forecast case, they know variation in model output is due to differing climate-related assumptions rather than differing economic assumptions.

But a funny thing happens when one tries to make an economic growth forecast for 100-year periods, as the IPCC has: Very small changes in assumptions make enormous differences.  Here is a simple example.  An economy that grows by 3% per year will be 19x larger in 100 years.  However, if that economy were to grow instead by 4% rather than 3%, it will be 51x larger in 100 years.  So a change in the growth rate by one percentage point yields a final size nearly 2.7 times larger.   The same is true with forecasting CO2 growth – a very small change in assumptions can lead to very large differences in absolute production.

After release of the 3rd IPCC report in 2001, researchers Ian Castles, formerly the head of Australia’s national office of statistics, and David Henderson of the Westminster Business School and formerly the chief economist of the OECD, decided to scrutinize the IPCC’s economic assumptions.  They found that the IPCC had made a fundamental mistake in crafting their econometrics, one that caused all of their economic growth estimates (and therefore estimates of CO2 production) to be grossly overestimated.  Based on the IPCC assumptions, South Africa ends up with a GDP per capita far in excess of the United States by the year 2100.  Incredibly, the IPCC numbers imply that Algeria, Argentina, Libya, Turkey, and North Korea will all pass the US in per capita income by the end of the century.

Beyond making it clear that there is an element of the absurd in the IPCC’s economic forecasting approach, these errors tend to inflate CO2 forecasts in two ways.  First, CO2 forecasts are raised because, in the models, larger economies produce more CO2.  Second, though, the models assume different rates for CO2 production per unit of GDP for each country.  Most of the countries the IPCC shows growing so fast – Algeria, South Africa, Libya, North Korea, etc. – have lower than average CO2 efficiencies (i.e. higher than average CO2 production per unit of GDP), so excess growth assumptions in these countries has a disproportionate impact on projected CO2 emissions.  By the way, it would be interesting to see if the IPCC is using marginal rather than average rates.  For example, France has a very low average rate of CO2 per unit of GDP because of its nukes, but its marginal growth is met mostly with fossil fuels.

I can’t say whether these same mistakes exist in the 2007 4th Assessment.  However, since the IPCC flatly rejected Castles and Henderson’s critique, it is likely the same methodology was used in 2007 as in 2001.  For example, here are the CO2 emissions forecasts from the 4th assessment – notice most all of them have a step-change increase in slope between history and the future.  Just look at the jump across the dotted line in lead case A1B, and several are even steeper.

So what does this mean?  Remember, small changes in growth rate make big differences in end values.  For example, below are the IPCC fourth assessment results for CO2 concentration.  If CO2 concentrations were to increase at about the same rate as they are today, we would expect an end value in 2100 of between 520 and 570 ppm, as opposed to the IPCC numbers below where the projection mean is over 800 in 2100.  The difference is in large part in the economic growth forecasts. 

Since it is not at all clear that the IPCC has improved its forecasting methodology over the past years, it is instructive as one final exercise to go back to the 1995 emissions scenarios in the 2nd assessment. Though the scale is hard to read, one thing is clear – only 10 years later we are well below most of the forecasts, including the lead forecast is92a (this over-forecasting has nothing to do with Kyoto, the treaty’s impact has been negligible, as will be discussed later).  One can be assured that if the forecasts are already overstated after 10 years, they will be grossly overstated in 100.

Climate Sensitivity and the Role of Positive Feedbacks

As discussed earlier, climate sensitivity generally refers to the expected reaction of global temperatures to a arbitrary change in atmospheric CO2 concentration.  In normal usage, it is usually stated as degrees Celsius of global warming from a doubling in CO2 concentrations from pre-industrial levels (approx 280 ppm to 560 ppm).  The IPCC and most AGW supporters put this number at about 3.5 to 4.0 degrees C. 

But wait – earlier I said the number was probably more like 1.0C, and that it was a diminishing return.  Why the difference?  Well, it has to do with something called feedback effects.

Before I get into these, let’s think about a climate sensitivity of 4 degrees C, just from a historical standpoint.  According to the IPCC, CO2 has increased by about 100ppm since 1880, which is about 36% of the way to a doubling.  Over this same time period, global temperatures have increased about 0.7C. Since not even the most aggressive AGW supporter will attribute all of this rise to CO2 levels, let’s be generous and credit CO2 with 0.5C. So if we are 36% of the way to a doubling, and giving CO2 credit for 0.5 degrees, this implies that the sensitivity is probably not more than 1.4 degrees C.  And we only get a number this high if we assume a linear relationship – remember that CO2 and temperature are a diminishing return relation (chart at right), so future CO2 has less impact on temperature than past CO2, so 1.4 would be at the high end.  In fact, using the logarithmic relationship we saw before, 0.5 degrees over 36% of the doubling would imply a sensitivity around 1.0.  So, based on history, we might expect at worst another 0.5C from warming over the next century. 

Most AGW supporters would argue that the observed sensitivity over the last 30 years has been suppressed by dimming/sulfate aerosols.  However, to get a sensitivity of 4.0, one would have to assume that without dimming, actual warming would have been about 2.0C.  This means that for the number 4.0 to be right,

1. Absolutely nothing else other than CO2 has been causing warming in the last 50 years AND

2. Sulfate aerosols had to have suppressed 75% of the warming, or about 1.5C, numbers far larger than I have seen anyone suggest.  Remember that the IPCC classifies our understanding of this cooling effect, if any, as “low”

But in fact, even the IPCC itself admits that its models assume higher sensitivity than the historically observed sensitivity.  According to the fourth IPCC report, a number of studies have tried to get at the sensitivity historically (going back to periods where SO2 does not cloud the picture).   Basically, their methodology is not much different in concept than the back of the envelope calculations I made above.

These are shown in a) below, which shows a probability distribution of what sensitivity is (IPCC4 p. 798). Note many of the highest probability values of these studies are between 1 and 2.  Also note that since CO2 content is, as the IPCC has argued, higher than it has been in recorded history, any sensitivities calculated on historical data should be high vs. the sensitivity going forward.  Now, note that graph c) shows how a number of the climate models calculate sensitivity.  You can see that their most likely values are consistently higher than any of the historical studies from actual data.  This means that the climate models are essentially throwing out historical experience and assuming that sensitivity is 1.5 to 2 times higher going forward, despite the fact a diminishing return relationship says it should be lower.

Sensitivity, based on History

Sensitivity that is built into the models  (Sorry, I still have no idea what “constrained by climatology” means, but the text of the report makes it clear that these sensitivities popped out of climate models

So how do these models get to such high sensitivities?  The answer, as I have mentioned, is positive feedback.

Let me take a minute to discuss positive feedbacks.  This is something I know a fair amount about, since my specialization at school in mechanical engineering was in control theory and feedback processes.  Negative feedback means that when you disturb an object or system in some way, forces tend to counteract this disturbance.  Positive feedback means that the forces at work tend to reinforce or magnify a disturbance.

You can think of negative feedback as a ball sitting in the bottom of a bowl.  Flick the ball in any direction, and the sides of the bowl, gravity, and friction will tend to bring the ball back to rest in the center of the bowl.  Positive feedback is a ball balanced on the pointy tip of a mountain.  Flick the ball, and it will start rolling faster and faster down the mountain, and end up a long way away from where it started with only a small initial flick.

Almost every process you can think of in nature operates by negative feedback.  Roll a ball, and eventually friction and wind resistance bring it to a stop.  There is a good reason for this.  Positive feedback breeds instability, and processes that operate by positive feedback are dangerous, and usually end up in extreme states.  These processes tend to "run away."   I can illustrate this with an example: Nuclear fission is a positive feedback process.  A high energy neutron causes the fission reaction, which produces multiple high energy neutrons that can cause more fission.  It is a runaway process, and it is dangerous and unstable.  We should be happy there are not more positive feedback processes on our planet.

Since negative feedback processes are much more common, and since positive feedback processes almost never yield a stable system, scientists assume that processes they meet are negative feedback until proven otherwise.  Except in climate, it seems, where everyone assumes positive feedback is common.

In global warming models, water vapor plays a key role as both a positive and a negative feedback loop to climate change.  Water vapor is a far more powerful greenhouse gas than CO2, so its potential strength as a feedback mechanism is high.  Water comes into play because CO2 driven warming will put more water vapor in the atmosphere, because greater heat will vaporize more water.  If this extra vapor shows up as more humid clear air, then this in turn will cause more warming as the extra water vapor absorbs more energy and accelerates warming.  However, if this extra water vapor shows up as clouds, the cloud cover will tend to reflect energy back into space and retard temperature growth. 

Which will happen?  Well, nobody knows.  The IPCC4 report admits to not even knowing the sign of water’s impact (e.g whether water is a net positive or negative feedback) in these processes.  And this is just one example of the many, many feedback loops that scientists are able to posit but not prove. And climate scientists are coming up with numerous other positive feedback loops.  As one author put it:

Regardless, climate models are made interesting by the inclusion of "positive feedbacks" (multiplier effects) so that a small temperature increment expected from increasing atmospheric carbon dioxide invokes large increases in water vapor, which seem to produce exponential rather than logarithmic temperature response in the models. It appears to have become something of a game to see who can add in the most creative feedback mechanisms to produce the scariest warming scenarios from their models but there remains no evidence the planet includes any such effects or behaves in a similar manner.

Note that the majority of the warming in these models appears to be from these feedback processes.  Though it is hard to pick it out exactly, section 8.6 of the fourth IPCC report seems to imply these positive feedback processes increase temperature 2 degrees for every one degree from CO2. This explains how these models get from a sensitivity of CO2 alone of about 1.0 to 1.5 degrees to a sensitivity of 3.5 or more degrees – it’s all in the positive feedback.

So, is it reasonable to assume these feedback loops? First, none have really been proven empirically, which does not of course necessarily make them wrong. .  In our daily lives, we generally deal with negative feedback:  inertia, wind resistance, friction are all negative feedback processes.  If one knew nothing else, and had to guess if a natural process was governed by negative or positive feedback, Occam’s razor would say bet on negative.   Also, we will observe in the next section that when the models with these feedbacks were first run against history, they produced far more warming than we have actually seen (remember the analysis we started this section with – post-industrial warming implies 1-1.5 degrees sensitivity, not four).

Perhaps most damning is to ask, if this really is such a heavily positive feedback process, what stops it?  Remember the chart from earlier (show again at the right), showing the long-term relationship of CO2 and warming.  Also remember that the data shows, and even AGW supporters acknowledge, that temperature rises led CO2 rises by about 800 years. Their explanation is that “something” caused the temperature to start upwards.  This higher temperature, as it warmed the oceans, caused CO2 to outgas from the oceans to the atmosphere.  Then, this new CO2 caused the warming to increase further.  In other words, outgassing CO2 from the oceans was a positive feedback to the initial temperature perturbation. In turn, the IPCC argues there are various other positive feedbacks that multiply the effect of the additional warming from the CO2.  This is positive feedback layered on positive feedback.  It would be like barely touching the accelerator and having the car start speeding out o f control.

So the question is, if global temperature is built on top of so many positive feedbacks and multipliers, what stops temperature form rising once it starts?  Why didn’t the Earth become Venus in any of these events? Because, for whatever else it means, the chart above is strong evidence that temperature does not run away. 

I have seen two suggestions, neither of which is compelling.  The first is that the oceans ran out of CO2 at some point.  But that makes no sense.  We know that the oceans have far more CO2 than could ever be liberated entirely to the atmosphere today, and besides,  the record above seems to claim that CO2 in the atmosphere never really got above there it was say in 1880.

The second suggestion is based on the diminishing return relationship of CO2 to temperature.  At some point, as I have emphasized many times, CO2’s ability to absorb infrared energy is saturated, and incremental quantities have little effect.  But note in the IPCC chart above, CO2 on the long time scale never gets as high as it is today.  If you argue that CO2’s absorption ability was saturated in earlier events, then you have to argue that it is saturated today, and that incremental CO2 will have no further warming effect, which AGW supporters are certainly NOT arguing.  Any theory based on some unknown negative feedback has to deal with the same problem:  If one argues that this negative feedback took over at the temperature peaks (in black) doesn’t one also have to argue that it should be taking over now at our current temperature peak?  The pro-AGW argument seems to depend on an assumption of negative feedbacks in the past that for some reason can’t be expected to operate now or in the future.  Why?

In fact, we really have not seen any evidence historically of these positive feedback multipliers.  As I demonstrated at the beginning of this chapter, even assigning as much as 0.5C of the 20th century temperature increase to CO2 only implies a sensitivity just over 1.0, which is about what we would expect from CO2 alone with no feedbacks.  This is at the heart of problems with AGW theory – There is no evidence that climate sensitivity to CO2 is anywhere near large enough to justify the scary scenarios spun by AGW supporters nor to justify the draconian abatement policies they advocate.

My tendency is to conclude that in fact, positive feedbacks do not dominate climate, just as they do not dominate any long-term stable system.  Yes, certain effects can reasonably be said to amplify warming (ice albedo is probably one of them) but there must exist negative feedbacks that tend to damp out temperature movements.  Climate models will never be credible, and will always overshoot, until they start building in these offsetting forcings.

Climate Models had to be aggressively tweaked to match history

A funny thing happened when they first started running climate models with high CO2 sensitivities in them against history:  The models grossly over-predicted historic warming.  Again, remember our previous analysis – historical warming implies a climate sensitivity between 1 and 1.5.  It is hard to make a model based on a 3.5 or higher sensitivity fit that history.  So it is no surprise that one can see in the IPCC chart below that the main model cases are already diverging in the first five years of the forecast period from reality, just like the Superbowl predictors of the stock market failed four years in a row.  If the models are already high by 0.05 degree after five years, how much will they overshoot reality over 100 years?

In a large sense, this is why the global climate community has latched onto the global dimming / aerosols hypothesis so quickly and so strongly.  The possible presence of a man-made cooling element in the last half of the 20th century, even one that the IPCC fourth report ranks our understanding of as “low,” gives modelers a valuable way to explain why their models are overstating history.  The aerosols hypothesis is valuable for two reasons:

· Since SO2 is prevalent today, but is expected to go down in the future, it allows modelers to forecast much higher warming and climate sensitivity in the future than has been observed in the past.

· Our very lack of understanding of the amount, if any, of such aerosol cooling is actually an advantage, because it allows modelers to set the value of such cooling at whatever value they need to make their models work

I know the last statement seems unfair, but in reading the IPCC and other reports, it appears to me that aerosol cooling values are set in exactly this way – as what we used to call a “plug” figure between actual temperatures and model output.  While this may seem a chancy and fairly circular reasoning, it makes sense for scientists because they trust their models.  They really believe the outputs are correct, such that any deviation is not attributed to their assumptions about CO2 or climate sensitivity, but to other man-made effects.

But sulfates are not the only plug being used to try to make high sensitivity models match a lower sensitivity past.  You can see this in the diagram below from the fourth IPCC report.  This is their summary of how their refined and tweaked models match history. 

The blue band is without anthropogenic effects. The pink band is with anthropogenic effects, including warming CO2 and cooling aerosols.  The black line is measured temperatures (smoothed out of course).

You can see the pink band which represents the models with anthropogenic effects really seems to be a lovely fit, which should make us all nervous.  Climate is way too chaotic a beast to be able to model this tightly.   In fact, given uncertainties and error bars on our historical temperature measurements, climate scientists are probably trumpeting a perfect fit here to the wrong data.  I am reminded again of a beautiful model for presidential election results with a perfect multi-decadal fit based on the outcome of NFL football games. 

But ignoring this suspiciously nice fit, take a look at the blue bar. This is what the IPCC models think the climate would be doing without anthropogenic effects (both warming CO2 and cooling sulfates, for example).  With the peaked shape (which should actually be even more pronounced if they had followed the mid-century temperature peak to its max) they are saying there is some natural effect that is warming things until 1950 and then turns off and starts cooling, coincidently in the exact same year that anthropogenic effects start taking off.  I challenge you to read the IPCC assessment, all thousand or so pages, and find anywhere in that paper where someone dares to say exactly what this natural effect was, or why it turned off exactly in 1950. 

The reality is that this natural effect is another plug.  There is no actual empirical data to back up the blue line (in fact, as we will see in the alternate theories section, there is good empirical data that this blue band is wrong).  Basically, climate scientists ran their models against history, and found that even with their SO2 plug, they still didn’t match well – they were underestimating early century warming and over-estimating late century warming.  Remember that the scientists believe their models and their assumptions about a strong CO2 effect, so they have modeled the non-anthropogenic effect by running their models, tuning them to historical actuals, and then backing out the anthropogenic forcings to see what is left.  What is left, the plug figure, is the blue line.

Already, the models used by the IPCC tend to overestimate past warming even if all past warming is attributable to anthropogenic causes.  If anthropogenic effects explain only a fraction of past warming, then the current models are vastly overstated, good for stampeding the populous into otherwise unpopular political control over the economy, but of diminished scientific value.

The note I will leave you with is this:  Do not gain false confidence in the global climate models when they show you charts that their outputs run backwards closely match history.  This is an entirely circular argument, because the models have been built, indeed forced, to match history, with substantial plug figures added like SO2 effects and non-anthropogenic climate trends, effects for which there are no empirical numbers.

The table of contents for the rest of this paper, A Layman’s Guide to Anthropogenic Global Warming (AGW) is hereFree pdf of this Climate Skepticism paper is here and print version is sold at cost here.

The open comment thread for this paper can be found here. 

Chapter 6 (Skeptics Guide to Global Warming): Alternate Explanations of Warming

The table of contents for the rest of this paper, A Layman’s Guide to Anthropogenic Global Warming (AGW) is hereFree pdf of this Climate Skepticism paper is here and print version is sold at cost here.

Solar Irradiance

If you walked into a room and found that it was too hot, would you, as a first step:

  1. Measure the air to find anomalies in the mix of gasses
  2. Count the number of people in the room, to assess the effect of body heat on the room’s temperature
  3. Check the thermostat on the furnace

If you answered #3, sorry, but you can’t join the IPCC.  If you really want to irritate an AGW supporter, ask about the sun.  To AGW supporters, only a Luddite would check the sun’s output when they could instead be obsessing over the increase in CO2 by 0.009% of the atmosphere.

When they looked at the problem, the IPCC decided that over the last 50 years, the sun has been irrelevant to warming.  Note that the blue band in this chart (described in more detail in the last section), the IPCC thinks that without man, the world would have cooled over the last 50 years:

Further, when they detailed different climate forcings, the forcing from changing solar irradiance was a trivial rounding error (though they had the good grace to mark their understanding of this as “low”) meaning the sun has very little effect vs. what the sun had in 1850 (in the Little Ice Age!)

But it turns out, interestingly, that solar irradiance may be close to its highest point in centuries.  Al Gore says that current global temperatures are the highest they have been in 1000 years.  A new study by the Institute of Astronomy in Zurich says that the "sun is more active now than it has been at anytime in the previous 1,000 years."  Related?

Sunspots have been monitored on the Sun since 1610, shortly after the invention of the telescope. They provide the longest-running direct measurement of our star’s activity.

The variation in sunspot numbers has revealed the Sun’s 11-year cycle of activity as well as other, longer-term changes.

In particular, it has been noted that between about 1645 and 1715, few sunspots were seen on the Sun’s surface.

This period is called the Maunder Minimum after the English astronomer who studied it.

It coincided with a spell of prolonged cold weather often referred to as the "Little Ice Age". Solar scientists strongly suspect there is a link between the two events – but the exact mechanism remains elusive….

But the most striking feature, he says, is that looking at the past 1,150 years the Sun has never been as active as it has been during the past 60 years.

Over the past few hundred years, there has been a steady increase in the numbers of sunspots, a trend that has accelerated in the past century, just at the time when the Earth has been getting warmer.

The data suggests that changing solar activity is influencing in some way the global climate causing the world to get warmer.

We can look at solar output over large time frames by looking at the production of carbon-14 (less is produced in years of high solar activity, and vice versa).  The analysis below used the ratio of oxygen isotopes in the stalagmites to estimate the water temperature at the time they were formed.  The result is an interesting correlation between solar activity and a global temperature proxy over a long time-scale (Graph from Neff et al., 2001):

Over the last 1000 years, we see that (again using a reversed scale of C14 as a proxy) solar activity is highly correlated with long term temperature trends (I have used the pre-Mann chart, because while it may over-emphasize the Medieval Warm Period, I still think such a period existed).

                Solar Output Anomaly                                                                      

              Temperature Anomaly


Look at the following reconstruction data by Judith Lean of the Naval Research Library and charted from her data at NOAA by Junkscience.com shows that interestingly, the sun’s output does appear to be higher today than they have been in many, perhaps hundreds of years


Would such increased activity be expected to result in higher Earth temperatures?  I don’t know, and there are some issues one has to be careful with on this chart.  Most importantly the scaling: While the shape of the curve looks a lot like the temperature trend over the last 400 years, note that the entire variation from the low to the high point is only about 0.25% – the scaling makes it look more dramatic.  Of course, the same could be said for global temperature, where a half degree C temperature increase on an absolute Kelvin scale would only be about 0.17%, so an argument can be made that on a percentage basis, this change in irradiance is about the same order of magnitude as our change in temperature.  A more sophisticated comparison might say that since black body radiation is related to absolute temperature to the fourth power, .25% increase in irradiance would be expected to heat the Earth by .06%.

The chart on the above left compares the recent temperature anomaly to solar irradiance, while the chart on the right compares it to CO2 concentrations.  Neither is a beautiful fit (and one may have to include aerosols in either scenario to account for 1970’s cooling) but solar irradiance seems at least as good as that of CO2.  Remember, the IPCC shows the world cooling due to solar effects during the same time the red solar irradiance line is peaking. 

Recently Alexander et. al. in have done some very comprehensive work relating solar irradiance and rainfall.  The study posits that one of the reasons for less than perfect fit of sunspot and irradiance data with temperature is that the Sun actually works on a 21 year cycle when the sunspot cycle is combined with the cyclical wobble of the Suns motion through space.  The study concluded:

The Intergovernmental Panel on Climate Change (IPCC) (2001) dismisses the view that solar activity has a meaningful influence on global climate. The basis for this view is that variations in the receipt of solar activity are too small to account for variations in the climatic responses. These variations were determined from satellite and other observations. What the IPCC scientists failed to appreciate is that changes in the level of solar radiation received on earth are amenable to precise calculation. The variations are well in excess of the IPCC value of +0,3 Wm–2 quoted earlier.

One of the interesting things about solar output is that, if it is really higher, we should see effects on other planets, not just on Earth.  And, in fact, a lot of evidence has been pouring in over the last 5 years from astronomers (not climate guys) that the rest of the solar system has been warming dramatically.

Take Mars, for example.  Mar’s ice caps have been melting and diminishing since NASA’s Mars Global Surveyor and Odyssey started to measure them around 2002. 

Changes in the red spot on Jupiter seem to be a sign of warming temperatures.  And Neptunes moon Triton is warming.  We have to be careful with how we draw conclusions on these outer planets, since their “year” is so long, seasonal changes can last decades. 

And on Neptune:

As seen in Figure 1, Neptune has been getting brighter since around 1980; furthermore, infrared measurements of the planet since 1980 show that the planet has been warming steadily from 1980 to 2004. As they say on Neptune, global warming has become an inconvenient truth. But with no one to blame, Hammel and Lockwood explored how variations in the output of the Sun might control variations in the brightness of Neptune.

Figure 1 (a) represents the corrected visible light from Neptune from 1950 to 2006; (b) shows the temperature anomalies of the Earth; (c) shows the total solar irradiance as a percent variation by year; (d) shows the ultraviolet emission from the Sun (Source: Hammel and Lockwood (2007)).

What would seem so simple statistically is complicated by the degrees of freedom in the various time series which is related to the serial correlation in the data (e.g., next year’s value is highly dependent on this year’s value). Nonetheless, they find that the correlation coefficient between solar irradiance and Neptune’s brightness is near 0.90 (1.00 is perfect). The same relationship is found between the Earth’s temperature anomalies and the solar output. Hammel and Lockwood note “In other words, the Earth temperature values are as well correlated with solar irradiance (r = 0.89) as they are with Neptune’s blue brightness (|r| > 0.90), assuming a 10-year lag of the Neptune values.” The temporal lag is needed to account for the large mass of Neptune that would require years to adjust to any changes in solar output.

Hammel and Lockwood conclude that “In summary, if Neptune’s atmosphere is indeed responding to some variation in solar activity in a manner similar to that of the Earth albeit with a temporal lag” then “Neptune may provide an independent (and extraterrestrial) locale for studies of solar effects on planetary atmospheres.”

More on the sun’s variance and climate change here.

Cosmic Rays

One of the problems with irradiance as a driver for climate change is that though the changes seem to be fairly well correlated with the temperature anomaly, many scientists think the magnitude is too small to totally account for temperature changes.  It is ironic that AGW supporters use this as a refutation of the sun’s effect, since they have exactly the same problem with CO2, and must posit huge positive feedback loops to justify their forecasts. 

A second, newer theory has emerged as to a potential second warming effect of solar output.  To understand it, we have to start with clouds.  For those that don’t live in a hot climate like I do here in Phoenix, I will give everyone a bit of background – clouds cool things off.  Ok, as with everything in climate, things are actually far more complicated – high clouds can sometimes cause warming, and nighttime clouds can actually slow cooling.  Never-the-less, in general, cloudcover cools things off by blocking out and reflecting the sun’s energy.

Clouds are in fact such a strong cooling force that is has been estimated by several sources (Theodor Landscheidt, 1998) that having clouds cover 1% more of the Earth’s surface would cancel the heating effect of a doubling of CO2.   In fact, it was one of my criticisms earlier that AGW theory seems overly intent on finding positive feedback loops, while not considering negative feedbacks seriously enough – one such potential negative feedback is that on a warmer Earth, more water is evaporated into clouds, in turn cooling things back off.

But recently, an interesting new theory on cloud formation has emerged.  In short, it holds that cosmic rays, which are the high energy particles that arrive at Earth from supernovas, spur cloud formation by ionizing air molecules that act as seeds for water condensation and cloud formation.  This sounds wild, but really no wilder than warming by a gas (CO2) that makes up a near trivial portion of the atmosphere.  Like CO2 warming, this effect has been observed in various laboratory chambers.  But is it really a measurable driver of climate?

Henrik Svensmark and Eigil Fris-Christensen looked at historic data on cloud cover and cosmic ray incidence, from various measuring points.  Their data was extended and refined by Shiva in 2005.

Cosmic rays vs. CO2 detailed

So what changes cosmic ray flux to the Earth?  The biggest influence is the sun.  When the sun’s output is high, cosmic rays are prevented from hitting the Earth, and vice versa.  So high solar activity corresponds to low cosmic ray flux and therefore lower cloud formation and higher temperatures. 

While the link between solar irradiance levels and warming is pretty straight forward, the cosmic ray cloud formation proposition is still in its infancy.  Those of us who criticize AGW supporters for running past the evidence on CO2 should not make the same mistake on cosmic rays, and movies such as The Global Warming Swindle have gone too far in portraying this alternate theory as fact.

Man’s Land Use

Recently, Roger Pielke has done a substantial amount of research on a different type of anthropogenic forcing.  Specifically, he has hypothesized that man’s changing patterns of land use can be a substantial driver of regional climate, including temperature and even more particularly, precipitation.   For example, clearing relatively dry land and replacing it with irrigated agriculture substantially changes to the local heat balance,  not the least by increasing humidity.  Dr. Pielke explains summarizes the consequences on his web site:

Humans are significantly altering the global climate, but in a variety of diverse ways beyond the radiative effect of carbon dioxide. The IPCC assessments have been too conservative in recognizing the importance of these human climate forcings as they alter regional and global climate. These assessments have also not communicated the inability of the models to accurately forecast the spread of possibilities of future climate. The forecasts, therefore, do not provide any skill in quantifying the impact of different mitigation strategies on the actual climate response
that would occur.

The table of contents for the rest of this paper, A Layman’s Guide to Anthropogenic Global Warming (AGW) is hereFree pdf of this Climate Skepticism paper is here and print version is sold at cost here.

The open comment thread for this paper can be found here. 

Chapter 7 (Skeptics Guide to Global Warming): The Effects of Global Warming

The table of contents for the rest of this paper, A Layman’s Guide to Anthropogenic Global Warming (AGW) is hereFree pdf of this Climate Skepticism paper is here and print version is sold at cost here.

There is no area in global warming discussions where AGW advocates have done more to shoot down their own credibility than in the absolutely egregious science and absurd claims that have been made about the potential negative effects of global warming.  If AGW advocates are frustrated that skeptics question their science and their credibility, they need to look no further than their own claims on global warming effects, which are so easy to prove wrong that it causes people like me to question everything else they say.

Why only bad stuff?

Whenever global warming is discussed in the press, the consequences are all universally bad.  Floods, famine, drought, pestilence, disease – they are all commonly predicted results of global warming.  But it is worth noting that in the 1970’s, when climate scientists and the press were in a panic over global cooling, the predicted results were… floods, famine, drought, pestilence, disease.  The implication is that we currently happen to be balanced on the knife edge of exactly the optimum world temperature for mankind.  Any change warmer or cooler results in net negative consequences.

This, of course, seems an odd coincidence.  Since man evolved into homo sapiens, he has experienced a wide range of cooler and warmer temperatures than we experience today.  It seems frankly amazing that in the mid 20th century we happened to be sitting at the absolute ideal temperature for modern technological society and agriculture.  Now, I guess you can argue that our society has made enormous investments based on the locations of the best crop lands, the height of the oceans, the typical paths of storms, etc., and that shifts in any of these would force an expensive restructuring of these investments. However, it is also worth noting that from the bottom of the Little Ice Age to say 1980, the world warmed at least a degree, and no one really noticed!  Everyone was still talking about cooling!

So I think that any honest analysis of the effects of global warming would have to acknowledge that there are likely both positive and negative effects.  While some areas may experience heat-induced droughts, other will be wetter as more moisture from the oceans is evaporated. While some crops will struggle, others, particularly in northern latitudes, will thrive due to longer growing seasons.  For each crop of vegetables that wilt in a heat wave there will be a crop of citrus that didn’t freeze. While more may die from the heat, fewer will die from the cold.  These may still net to a negative sum, but that net sum will be substantially less negative than a one-sided look at only the downsides of warming would arrive at.

One reason that warming impact analysis is hard is because while we may talk about the world warming a degree or two, the world does not warm evenly. Most climate models show the most warming on dry winter nights  (Siberian winters, for example, get a disproportionate share of the warming).  An extra summer degree in Arizona would suck; an extra winter degree in Siberia would probably be welcomed, and would likely extend growing seasons.

In the rest of this chapter, I will spend some time with a number of the most common “scary results” from global warming.

Ice melting / ocean rising 

In An Inconvenient Truth, Al Gore claims that oceans will rise twenty feet due to global warming.  Helpfully, a number of websites have been created to show what parts of the world (including much of Florida) would sink beneath the oceans like Atlantis with a 20-foot rise in sea level.

Fortunately, even most AGW supporters believe that Gore is wildly exaggerating, at least for any time period less than a couple of centuries.  The Fourth IPCC report (see chart below) predicts sea level rise by the year 2100 of … 12-15 inches.  And remember that this is based on forecasts of both CO2 production and climate sensitivity to CO2 that are arguably high by a factor of two or more.  From the fourth IPCC report (different columns are for different starting CO2 forecasts):

By the way, to give a sense of scale, the IPCC estimates that the oceans have already risen about 0.2 meters in the last 130 years or so:

One other interesting thing you can see from the sea level forecast chart is that even the IPCC considers ice melting virtually irrelevant.  That is because most of the surface level increase is from thermal expansion of the water as the oceans warm.  In the A1B case, for example, net worldwide ice melt raises oceans by about 4 inches in the next hundred years. 

This last conclusion may seem crazy to anyone who has watched the media of late or seen Mr. Gore’s movie.  Images of ice crashing into the ocean and sea ice retreating are common fodder for global warming visuals.  But the fact is that ice, like everything else in climate, is complicated.

  • North Pole:  Arctic sea ice melting is totally irrelevant to ocean surface levels.  Since the ice floats, even a 100% melting of the Arctic ice will not change sea level one bit, just as ice melting in your glass of water does not cause your glass to overflow. 

But some may argue that this ducks the question.  Does current, well-documented retreat of artic ice sheets provide independent confirmation of the magnitude of AGW?  In fact, though ice sheets are retreating, this seems to be part of a two hundred year trend that began long before man was burning fossil fuels in any quantity:

  • Alpine Glaciers:  We know that many Alpine glaciers around the world are retreating.  Some of this is surely from global warming, but some is also from fluctuations in precipitation.  In many cases, we have documented evidence that these glaciers have been retreating since the 19th century, and that they have been less extensive in the past.

Reid A. Bryson is Emeritus Professor and founding chairman of the University of Wisconsin Department of Meteorology—now the Department of Oceanic and Atmospheric Sciences and a member of the United Nations Global 500 Roll of Honor.  When asked about the retreat of Alpine glaciers, he says, “What do they find when the ice sheets retreat, in the Alps?  A silver mine! The guys had stacked up their tools because they were going to be back the next spring to mine more silver, only the snow never went,” he says. “There used to be less ice than now. It’s just getting back to normal.”

Alaska Geographic published a chart of the retreat of the glaciers at Glacier Bay, Alaska, showing most of the retreat occurred before the 2nd half of the 20th century:

One special note should be made of the glaciers on Kilimanjaro, because their retreat over the last 125 years has been well-documented and played a starring role in An Inconvenient Truth.  Analysis has shown that most the glacial retreat at Kilimanjaro occurred before 1953 (and therefore before most recent warming) and that the retreat has more to do with moisture in the air than with global warming.  One wonders why the movie, with glacial retreats around the world that are provably due to warming, would focus on one that is probably not due to warming.

· Greenland:  Greenland has a lot of ice, and there is not much doubt that if it all melted, the oceans would rise a lot.  However, we know that in the middle ages, Greenland was much warmer and had less extensive ice coverage (thus the name Greenland and the successful attempt to farm it for over a century)

While there is a lot of discussion about whether the Medieval Warm Period extended worldwide, most accept that it did cover the North Atlantic, including Greenland.  Boreholes, such as the Dahl-Jensen below, seem to prove out our historical information, showing a temperature peak around the year 1000.

· Antarctica: Something like 80-85% of the world’s ice is in Antarctica.  And no one really thinks it is melting or going to melt.  In fact, if you look at the marks on the IPCC chart above for the contribution of Antarctic ice to ocean levels, it has a net negative impact, which means the IPCC actually expects the Antarctic ice sheet to grow, not melt.

Whoa, that can’t be right!  Mr. Gore showed those videos of ice retreating in Antarctica.  Well, yes, sort of.  Scientists expect that global warming will make the sea currents that circle Antarctica a bit warmer, leading to more precipitation and more snowfall on the continent.  Besides, Antarctica is so damn cold that raising temperatures a few degrees is not going to melt anything. 

The one exception is the Antarctic Peninsula, which sticks out into the warmer oceans.  This land area, representing about 2% of the Antarctic land mass and even less of its total ice sheet, is expected to warm and lose ice while the other 98% gains ice.

Guess what?  Mr. Gore chose that little 2% to illustrate his movie.  Was he ignorant of the choice he was making, or did he know exactly what he was doing, telling the literal truth (that the peninsula is melting) but leading viewers to the wrong conclusion overall about Antarctic ice?

By the way, one last interesting fact that frankly, scientists don’t fully understand is the fact that the South Pole is really not experiencing any warming.  While the warming at the north pole exceeds the global average, the south pole shows little or no anomaly.


Hurricanes & Tornados

Alter Hurricane Katrina, the media storyline focused strongly on the role global warming may have played in increasing hurricane power and activity.  Lost in the rush to blame global warming was the fact that Katrina, when it made landfall, was not even a category 5 hurricane, and its devastation was due more to  a city sited below sea-level that did a poor job of managing its storm protection.

In fact, many hurricane experts do not agree with the argument that warming oceans can lead to more and stronger hurricanes.  In fact, hurricane activity is more related to the difference in temperatures between the cold and warmer waters, a difference AGW theory says should decrease rather than increase.  So is there reason to believe hurricanes are on the rise as global temperatures warm?  The answer, as shown below, seems to be no:

But what about storm damage?  It certainly seems like recent hurricanes have resulted in far more economic damage.  And they have, but for the simple reason that over the last several decades, Americans have put billions of dollars of expensive homes and other facilities in vulnerable Gulf and Atlantic coast locations.   Several years ago, Dr. RA Pielke and CW Landsea (that can’t really be the name of a scientist studying coastal strikes by hurricanes) attempted to correct hurricane damage numbers for the density and value of coastal real estate:

By this reckoning, it is hard to see any trend.

Another claim Mr. Gore makes in An Inconvenient Truth is that 2004 was the most active year for tornadoes ever in the United States, and that there has been a steady trend in increasing tornados as the globe has warmed.

And certainly if you look at the raw numbers, you might be worried:

But there is a little something Mr. Gore fails to mention.  During this time period, from 1950 to 2000, the technology and network for detecting tornados has improved vastly.  From the NOAA

With increased national doppler radar coverage, increasing population, and greater attention to tornado reporting, there has been an increase in the number of tornado reports over the past several decades. This can create a misleading appearance of an increasing trend in tornado frequency. To better understand the true variability and trend in tornado frequency in the US, the total number of strong to violent tornadoes (F3 to F5 category on the Fujita scale) can be analyzed. These are the tornadoes that would have likely been reported even during the decades before Dopplar radar use became widespread and practices resulted in increasing tornado reports. The bar chart below indicates there has been little trend in the strongest tornadoes over the past 55 years.

Oops!  In fact, tornado frequency seems to be falling as temperatures warm.  Do you think this was another honest mistake, like with Antarctica, or did Mr. Gore purposefully obfuscate the real story?

Temperature Extremes

Another argument is that global warming will lead to more temperature extremes, particularly record sweltering highs.  That seems logical enough, but Bruce Hall actually compiled the data and found something interesting.  He created a data base for each state which shows in what year that state’s monthly temperature records were set.   So for each state, he has the years when the twelve monthly high temperature records were set (e.g. year of highest Arizona Jan temp, year of highest Arizona Feb temp, etc.) and the years when the twelve monthly low temperature records were set.  Here, for example, is his data for Arizona:


So, for example, the record for the highest July temperature was set in 1905 at Parker, Arizona with a scorching 127 degrees.  The entry in his database would then be Arizona-July:  1905.  He notes that there is a bias in the data toward more recent years, since if the record was set in 1905 and tied in 1983, only the newer 1983 date will show in the data.  I would also observe that this data is uncorrected for urban heat island effects (as cities urbanize they get hotter, and effect that is different than CO2-cause global warming and is usually corrected for in global warming studies).  There is also a bias towards the present in having more measurement points today than 100 years ago:  More measurement points means that, over a state, one is more likely to pick up the true high (or low).

Though I have other problems with the anthropogenic global warming hypothesis, I have never really doubted that the world has warmed up over the last century. So even I, a skeptic, would expect a disproportionate number of the all-time high temperatures to be in the last decade, particularly without UHI correction and with the bias discussed above.  The global warming folks would argue that the effect should be doubly pronounced, since they claim that we are seeing not just a general heating, but an increase in volatility (ie more extreme variation around the mean).

But Hall doesn’t find this when he graphs the data. Take the 600 state monthly high temperature records that exist on the books today (50 states times 12 months) and graph the distribution of years in which these records were set:

Assuming about 120 years of data, you should expect to see a high temperature record on average in a database of 600 records at 5 per year, which is precisely where we have been of late and well below the record years in the thirties (remember the dust bowl?) and the fifties. It seems to actually show a reduction in temperatures or volatility or both.

This may seem impossible – how can the mean increase without causing a lot more new highs?  But remember what we discussed earlier – global warming is expected to be seen disproportionately in nighttime and winter temperatures.  This means that the mean can increase even as daytime summer highs don’t increase much.  In a sense, is the lows, not the highs, that are getting higher.

Vincent et al in 2005 did a study of temperature trends in South America from 1960-2000.  What they observed is exactly what we discussed here:  The number of warm days and cold days did not really change. The warming trend showed up as a decrease in cold nights and an increase in warm nights, meaning effectively that the diurnal (across 24 hours) temperature variation is narrowed. 

It’s a little hard to be scared by this.

Extinction and Disease

Biologist Josef Reichholf was interviewed recently in der Spiegel.  He is a strong conservationist, and certainly has his axe to grind with industrial society.  In fact he blames industrial agriculture and modern development for problems that species face. 

Many species are certainly threatened, but not by climate change….Many species have already fled from the countryside to the cities, which have been transformed into havens of biodiversity. We are also seeing another interesting phenomenon: Major cities, like Hamburg, Berlin and Munich, have formed heat islands where the climate has been two or three degrees warmer than in the surrounding countryside for decades. If higher temperatures are truly so bad, why do more and more animals and plants feel so comfortable in our cities?

On the contrary, there is much to be said for the argument that warming temperatures promote biodiversity. There is a clear relationship between biodiversity and temperature. The number of species increases exponentially from the regions near the poles across the moderate latitudes and to the equator. To put it succinctly, the warmer a region is, the more diverse are its species.

OK, but what about those polar bears?  We have all seen the media pictures of bears stranded on blocks of ice, as if all the arctic has melted out from under them.  Well, it turns out that polar bears have survived much warmer conditions.  We know polar bears existed as a separate species at least 125,000 years ago, and in the intervening years, there have been periods where Arctic sea ice melted completely during the summer months.  And yet polar bears still exist today.  Polar bears may be threatened by man’s hunting and encroachment on its hunting grounds, but not likely by our fossil fuel combustion.

AGW fear-mongering also extends to breathless predictions of increases in “tropical” diseases.  Reichholf also takes on this canard:

Many people truly believe that malaria will spread as temperatures rise. But malaria isn’t even a true tropical disease. In the 19th century, thousands of people in Europe, including Germany, the Netherlands and even Scandinavia, died of malaria, even though they had never gone abroad. That’s because this disease was still prevalent in northern and central Europe in previous centuries. We only managed to eliminate malaria in Europe by quarantining the sick, improving hygiene and draining swamps. That’s why I consider it virtually impossible that malaria would return to us purely because of climate change. If it does appear, it’ll be because it has been brought in somewhere.

Most of the world’s leading tropical disease experts tend to agree with Reichholf.  In fact, I would argue that diseases like Malaria are not diseases of the tropics but diseases of poverty and under-development.  Malaria is prevalent in Africa not because Africa is hot but because Africa is poor.  Asian tropical countries that have developed substantially over the last several decades have also greatly reduced malaria.  In fact, as I will discuss in later sections, by reducing world economic growth and slowing development in the third world in the name of CO2 reduction, we will actually increase rather than reduce these diseases.

Collapse of the Gulf Stream and Freezing of Europe

One of the recent hysteria’s has been that global warming will cause the Gulf Stream to collapse as Atlantic circulation patterns are radically altered, thus leading to the freezing of Europe.  More sober scientists have since essentially said “nevermind.”  The Gulf Stream and Atlantic circulation patterns are far more robust than this theory assumed, and, even if the Gulf Stream changes, proponents of the theory were overestimating the dependence of Europe on Gulf Stream warming.

Non-warming Effects of CO2

Interestingly, we may eventually decide that other non-climate effects of CO2 production actually present more tangible environmental threats.  In particular, recent studies have shown that more atmospheric CO2 is causing the PH of ocean surface layers to drop (ie become more acidic) leading potentially to coral kills and substantial changes in sea life.  At the same time, physicist Freeman Dyson argues that stratospheric cooling from man-made CO2 is much more a problem than surface warming, and is much more measurable and provable.  These topics are beyond my scope at this point, but something we may see more of in the future.

The table of contents for the rest of this paper, A Layman’s Guide to Anthropogenic Global Warming (AGW) is hereFree pdf of this Climate Skepticism paper is here and print version is sold at cost here.

The open comment thread for this paper can be found here.

Chapter 8 (Skeptics Guide to Global Warming): Kyoto and Policy Alternatives

The table of contents for the rest of this paper, A Layman’s Guide to Anthropogenic Global Warming (AGW) is hereFree pdf of this Climate Skepticism paper is here and print version is sold at cost here.

Kyoto Treaty

In the mid-1990’s, a number of western nations crafted a CO2-reduction treated named Kyoto for the city in which the key conference was held. The treaty called for signatory nations to roll back their CO2 emissions to below 1990 levels by a target date of 2012.  Japan, Russia, and many European nations signed the treaty; the United States did not.  In fact, the pact was ratified by 141 nations, but only calls for CO2 limits in 35 of these (so the other 106 were really going out on a limb signing it). China, India, Brazil and most of the third world are exempt from its limits.

We will discuss the costs and benefits of CO2 reduction a bit later. However, it is instructive to look at why Kyoto was crafted the way it was, and why the United States refused to sign, even when Al Gore was vice-president.

The most obvious flaw is that the entire developing world, including China, SE Asia, and India, are exempt. These countries account for 80% of the world’s population and the great majority of growth in CO2 emissions over the next few decades, and they are not even included. If you doubt this at all, just look at what the economic recovery in China over the past months has done to oil prices. China’s growth in hydrocarbon consumption will skyrocket over the coming years, and China is predicted to have higher CO2 production than the United States by 2009.

The second major flaw with the treaty is that European nations cleverly crafted the treaty so that the targets were relatively easy for them to make, and very difficult for the United States to meet.  Rather than freezing emissions at current levels at the time of the treaty, or limiting carbon emission growth rates, the treaty called for emissions to be rolled back to below 1990 levels. Why 1990? Well, a couple of important things have happened since 1990, including:

a. European (and Japanese) economic growth has stagnated since 1990, while the US economy has grown like crazy. By setting the target date back to 1990, rather than just starting from day the treaty was signed, the treaty effectively called for a roll-back of economic growth in the US that other major world economies did not enjoy.

b. In 1990, Germany was reunified, and Germany inherited a whole country full of polluting inefficient factories from the old Soviet days. Most of the dirty and inefficient Soviet-era factories have been closed since 1990, giving Germany an instant one-time leg up in meeting the treaty targets, but only if the date was set back to 1990, rather than starting at the time of treaty signing.

c. Since 1990, the British have had a similar effect from the closing of a number of old dirty Midlands coal mines and switching fuels from very dirty coal burned inefficiently to more modern gas and oil furnaces and nuclear power.

d. Since 1990, the Russians have an even greater such effect, given low economic growth and the closure of thousands of atrociously inefficient communist-era industries.

It is flabbergasting that US representatives could allow the US to get so thoroughly out-manuevered in these negotiations. Does anyone in the US really want to roll back the economic gains of the nineties, while giving the rest of the world a free pass? Anyway, as a result of these flaws, and again having little to do with the global warming argument itself, the Senate voted 95-0 in 1997 not to sign or ratify the treaty unless these flaws (which still exist in the treaty) were fixed.  Then-Vice-President Al Gore agreed that the treaty should not be signed without modifications, which were never made and which Europeans were never going to make.

By the way, enough time has elapsed that we have data on the progress of various countries in meeting these targets.  And if you leave out various accounting games with offsets of dubious value, most all the European nations, despite all the advantages described above, are still missing their targets.  The political will simply does not exist to hamstring their economies to the extent necessary to roll back CO2 growth.  Actual growth rates for CO2 emissions have been (source UN):


United States

Europea Union










You can see that the Europeans positioned themselves well in the 1990’s to make their targets.  Realize that as the treaty was negotiated, they already had a good idea of these numbers for 1990-1995 and even a few years beyond.  They knew that by selecting a 1990 baseline, they were already on target to meet the goals and the US would be far behind. Again, realize that the 1990-2000 EU performance on CO2 production had nothing to do with post-Kyoto regulatory responses and everything to do with the economic fundamentals we outlined above that would have existed with or without the treaty.

Since 2000, however, it has been a different story. European emissions have increased as their economies have recovered, at the same time the US experienced a post-9/11 slowdown.

By the way, the US is generally the great Satan in AGW circles because its per capita CO2 production is the highest in the world.  But this is in part because our economic output per capita is close to the highest in the world.  The US is about in the middle of the pack in efficiency, though behind many European countries which have much higher fuel taxes and heavier nuclear investments.

As an interesting side note, the US per capita CO2 emissions, as show below, have actually been flat to down since the early 1970’s.  To the extent that Europe is doing better at CO2 reduction than the US, it may actually be more of an artifact of their declining populations vs. America’s continued growth.

Finally, if you get really tired of the US-bashing, you can take some comfort that though the US is the #1 per capita producer of CO2, of which we are uncertain is even harmful, we have done a fabulous job reducing many other pollutants we are much more certain are harmful.  For example, the US has much lower SO2 production than most European nations and the water quality is better.  One could argue that the US has spent its abatement dollars on things that really matter.

Cost of the Solutions vs. the Benefits:  Why Warmer but Richer may be Better than Colder and Poorer

If you get beyond the hard core of near religious believers in the massive warming scenarios, the average global warming supporter would answer this paper by saying: "Yes there is a lot of uncertainty, but though the doomsday warming scenarios via runaway positive feedback in the climate can’t be proven, they are so bad that we need to cut back on CO2 production just to be on the safe side."

This would be a perfectly reasonable approach if cutting back on CO2 production was nearly cost-free.  But it is not.  The burning of hydrocarbons that create CO2 is an entrenched part of our lives and our economies. Forty years ago we might have had an easier time of it, as we were on a path to dramatically cut back on CO2 production via what is still the only viable technology to massively replace fossil fuel consumption — nuclear power.  Ironically, it was environmentalists that shut down this effort, and power industries around the world replaced capacity that would have gone nuclear mostly with coal, the worst fossil fuel in terms of CO2 production (per BTU of power, Nuclear and hydrogen produce no CO2, natural gas produces some, gasoline produces more, and coal produces the most).

Just halting CO2 production at current levels (not even rolling it back) would knock several points off of world economic growth.  Every point of economic growth you knock off guarantees you that you will get more poverty, more disease, more early death.  If you could, politically, even make such a freeze stick, you would lock China and India, nearly 2 billion people, into continued poverty just when they were about to escape it.  You would in the process make the world less secure, because growing wealth is always the best way to maintain peace.  Right now, China can become wealthier from peaceful internal growth than it can from trying to loot its neighbors. But in a zero sum world created by a CO2 freeze, countries like China would have much more incentive to create trouble outside its borders.  This tradeoff is often referred to as a cooler but poorer world vs. a richer but warmer world.  Its not at all clear which is better. 

What impact, warming?

We’ve already discussed just how much the popular media has overblown the effect of warming.  Sea levels may rise, but only by 15 inches in one hundred years, and even that based on arguably over-inflated IPCC models. There is no evidence that weather patterns will be more severe, or that diseases will spread, or that species will be threatened by warming.  And, since most of the warming has been and will be concentrated in winter and nights, we will see rising temperatures more in a narrowing of temperature variability rather than a drastic increase in summer high temperatures. Growing seasons, in turn, will be longer and deaths from cold, which tend to outnumber heat-related deaths, will decline. 

What impact, Intervention?

While the Kyoto treaty was a massively-flawed document, with current technologies a Kyoto type cap and trade approach is about the only way we have available to slow or halt CO2 emissions.  And, unlike the impact of warming on the world, the impact of such a intervention is very well understood by the world’s economists and seldom in fact disputed by global warming advocates.  Capping world CO2 production would by definition cap world economic growth at the rate of energy efficiency growth, a number at least two points below projected real economic growth.  In addition, investment would shift from microprocessors and consumer products and new drug research and even other types of pollution control to energy. The effects of two points or more lower economic growth over 50-100 years can be devastating:

  • Remember the power of compounded growth rates we discussed earlier.  A world real economic growth rate of 4% yields income fifty times higher in a hundred years.  A world real economic growth rate two points lower yields income only 7 times higher in 100 years.  So a two point reduction in growth rates reduces incomes in 100 years by a factor of seven!  This is enormous.  It means, literally, that on average everyone in a cooler world would make 1/7 what they would make in a warmer world.
  • Currently, there are perhaps a billion people, mostly in Asia, poised to exit millennia of subsistence poverty and reach the middle class.  Global warming intervention will likely consign these folks to continued poverty.  Does anyone remember that old ethics problem, the one about having a button that every time you pushed it, you got a thousand dollars but someone in China died.  Global warming intervention strikes me as a similar issue – intellectuals in the west      feel better about man being in harmony with the Earth but a billion Asians get locked into poverty.
  • Lower world economic growth will in turn considerably shorten the lives of billions of the world’s poor
  • A poorer world is more vulnerable to natural disasters.  While AGW advocates worry (needlessly) about hurricanes and tornados in a warmer world, what we can be certain of is that these storms will be more devastating and kill more people in a poorer world than a richer one.
  • The unprecedented progress the world is experiencing in slowing birth rates, due entirely to rising wealth, will likely be reversed.  A cooler world will not only be poorer, but likely more populous as well.  It will also be a hungrier world, particularly if a cooler world does indeed result in lower food production than a warmer world
  • A transformation to a prosperous middle class in Asia will make the world a much safer and more stable place, particularly vs. a cooler world with a billion Asian poor people who know that their march to progress was halted by western meddling.
  • A cooler world would ironically likely be an environmentally messier world.  While anti-growth folks blame all environmental messes on progress, the fact is that environmental impact is      a sort of inverted parabola when plotted against growth.  Early industrial growth tends to pollute things up, but further growth and wealth provides the resources and technology to clean things up.  The      US was a cleaner place in 1970 than in 1900, and a cleaner place today than in 1970.  Stopping or drastically slowing worldwide growth would lock much of the developing world, countries like Brazil and China and Indonesia, into the top end of the parabola.  Is Brazil, for example, more likely to burn up its rain forest if it is poor or rich?

The Commons Blog links to this study by Indur Goklany on just this topic:

If global warming is real and its effects will one day be as devastating as some believe is likely, then greater economic growth would, by increasing greenhouse gas (GHG) emissions, sooner or later lead to greater damages from climate change. On the other hand, by increasing wealth, technological development and human capital, economic growth would broadly increase human well-being, and society’s capacity to reduce climate change damages via adaptation or mitigation. Hence, the conundrum: at what point in the future would the benefits of a richer and more technologically advanced world be canceled out by the costs of a warmer world?

Indur Goklany attempted to shed light on this conundrum in a recent paper presented at the 25th Annual North American Conference of the US Association for Energy Economics, in Denver (Sept. 21, 2005). His paper — "Is a richer-but-warmer world better than poorer-but-cooler worlds?” — which can be found here, draws upon the results of a series of UK Government-sponsored studies which employed the IPCC’s emissions scenarios to project future climate change between 1990 and 2100 and its global impacts on various climate-sensitive determinants of human and environmental well-being (such as malaria, hunger, water shortage, coastal flooding, and habitat loss). The results indicate that notwithstanding climate change, through much of this century, human well-being is likely to be highest in the richest-but-warmest world and lower in poorer-but-cooler worlds. With respect to environmental well-being, matters may be best under the former world for some critical environmental indicators through 2085-2100, but not necessarily for others.

This conclusion casts doubt on a key premise implicit in all calls to take actions now that would go beyond “no-regret” policies in order to reduce GHG emissions in the near term, namely, a richer-but-warmer world will, before too long, necessarily be worse for the globe than a poorer-but-cooler world. But the above analysis suggests this is unlikely to happen, at least until after the 2085-2100 period.

Policy Alternatives

Above, we looked at the effect of a cap and trade scheme, which would have about the same effect as some type of carbon tax.  This is the best possible approach, if an interventionist approach is taken.  Any other is worse.

The primary other alternative bandied about by scientists is some type of alternative energy Manhattan project.  This can only be a disaster. Many scientists are technocratic fascists at heart, and are convinced that if only they could run the economy or some part of it, instead of relying on this messy bottom-up spontaneous order we call the marketplace, things, well, would be better. The problem is that scientists, no matter how smart they are, miss with their bets because the economy, and thus the lowest cost approach to less CO2 production, is too complicated for anyone to understand or manage.  And even if the scientists stumbled on the right approaches, the political process would just screw the solution up.  Probably the number one alternative energy program in the US is ethanol subsidies, which are scientifically insane since ethanol actually increases rather than reduces fossil fuel consumption. Political subsidies almost always lead to investments tailored just to capture the subsidy, that do little to solve the underlying problem.  In Arizona, we have thousands of cars with subsidized conversions to engines that burn multiple fuels but never burn anything but gasoline.  In California, there are hundreds of massive windmills that never turn, having already served their purpose to capture a subsidy.  In California, the state bent over backwards to encourage electric cars, but in fact a different technology, the hybrid, has taken off.

Besides, when has this government led technology revolution approach ever worked?  I would say twice – once for the Atomic bomb and the second time to get to the moon.  And what did either get us?  The first got us something I am not sure we even should want, with very little carryover into the civilian world.  The second got us a big scientific dead end, and probably set back our space efforts by getting us to the moon 30 years or so before we were really ready to do something about it or follow up the efforts.

If we must intervene to limit CO2, we should jack up the price of fossil fuels with taxes, or institute a cap and trade scheme which will result in about the same price increase, and the market through millions of individual efforts will find the lowest cost net way to reach whatever energy consumption level you want with the least possible cost.  (The only real current alternative that is rapidly deploy-able to reduce CO2 emissions anyway is nuclear power, which could be a solution but was killed by…the very people now wailing about global warming.)

The table of contents for the rest of this paper, A Layman’s Guide to Anthropogenic Global Warming (AGW) is hereFree pdf of this Climate Skepticism paper is here and print version is sold at cost here.

The open comment thread for this paper can be found here.