Category Archives: Skeptic Summaries

I Will Accept this Description

I think this description fits where I am pretty well:

Lawrence Solomon, a columnist for Canada’s National Post—and the victim of an earlier smear campaign—decided to ask who these “deniers” really are and what they really believe. What he found is telling: “Among all the deniers I have profiled,” Solomon writes, “I have never encountered one who disputes that there is such a thing as a greenhouse effect, or that carbon dioxide is a greenhouse gas…. The arguments are all about how powerful the effect is, especially when considered in combination with other factors, various feedback mechanisms both negative and positive, and other influences that might or might not overwhelm the effect of CO2.” In other words, Solomon found that the “deniers” are, in fact, not in denial at all. They are merely dissidents from the political orthodoxy of climate catastrophism.

Winning Video

My 3-minute climate video won second place in the Kids and Globaloney contest

The results surprise me a bit.  I found the 3-minute limit almost impossible to make work in the video contest, and thought my video, which I include below, was rushed.

A better version is the 9-minute version here which covers the same subjects but with a bit more leisure and explanation.  This video, however, is a bit dated.  As I write in the YouTube comments, I want to take a better shot at explaining the issues around positive feedback.  I think I can fix it with just a rewrite of the narration.  That longer video is here and below.

My really long video, 60-minutes in 6 parts, is here.

The Keystone Issue of Global Warming

It is silly to argue whether CO2 in the atmosphere can cause global warming: It clearly does.  The issue is not "if" but "how much".  The warming from man’s CO2 might be 8 degrees in a century, as Al Gore might argue, in which case man’s CO2 would be incredibly disruptive.  Or it might cause just a few tenths of a degree of warming, which might be unnoticeable within the noise of natural climate variation.

Interestingly, the key to understanding this issue of the amount of warming does not actually lie in greenhouse gas theory.  Most scientists, skeptics and alarmists alike, peg the warming directly from CO2 at between 0.3 and 1.0 degrees Celsius for a doubling in CO2 levels  (this notion of how much temperatures would increase for a doubling of CO2 levels is called climate sensitivity).  If this greenhouse gas warming was the only phenomenon at work, we would expect man-made warming over the next century even using the most dire assumptions to be less than 1C, or about the same amount we have seen (non-catastrophically) over the last century.  Warming forecasts of this magnitude would not in any way, shape, or form justify the draconian economic impacts of many current government carbon reduction proposals.

The key, as I have written before (and here), lies not in greenhouse gas theory itself but in the theory that the earth’s climate is dominated by positive feedback.  This theory hypothesizes that small changes in temperature from greenhouse gas increases would be multiplied 3,4,5 times or more by positive feedback effects, from changes in atmospheric water vapor to changing surface albedo.

Let me emphasize again:  The catastrophe results not from greenhouse gas theory, but from the theory of extreme climactic positive feedback.  In a large sense, all the debate in the media is about the wrong thing!  When was the last time you saw the words "positive feedback" in a media article about climate?

Christopher Monckton has an absolutely dead-on post at Roger Pielke’s blog about this feedback theory that I want to excerpt in depth.

This chart is a good place to start.  It shows the changes in the IPCC’s estimate for climate sensitivity to CO2 and how it has changed over the course of the reports.  More importantly, he splits the forecast between the amount due directly to Co2, and the amount due to the multiplicative effect of positive feedback.  The green bar is the direct contribution of Co2, and the pink is the feedback.

Fig3

We can observe a couple of things.  First, the IPCC’s estimate of the amount of warming due to CO2 directly via the greenhouse gas effect has actually been going down over time.  (Note that there are those, like Richard Lindzen, who suggest these numbers are still three times too high given that we have not observed a difference in surface and lower troposphere warming that greenhouse gas theory seems to predict).

Second, you will see that the IPCC’s overall forecasts of climate sensitivity have been going up only because their estimates of positive feedback effects have gone way up.  The IPCC assumes that feedback effects multiply warming from CO2 by three.  And note that the IPCC’s forecasts of feedback effects trail those of folks like James Hansen and Al Gore. 

So how confident are we in these feedback effects?  Well, it turns out we are not even sure of the sign!  As Monckton writes:

The feedback factor f accounts for at least two-thirds of all radiative forcing in IPCC (2007); yet it is not expressly quantified, and no “Level Of Scientific Understanding” is assigned either to f or to the two variables b and κ upon which it is dependent….

Indeed, in IPCC (2007) the stated values for the feedbacks that account for more than two-thirds of humankind’s imagined effect on global temperatures are taken from a single paper. The value of the coefficient z in the CO2 forcing equation likewise depends on only one paper. The implicit value of the crucial parameter κ depends upon only two papers, one of which had been written by a lead author of the chapter in question, and neither of which provides any theoretical or empirical justification for the IPCC’s chosen value. The notion that the IPCC has drawn on thousands of published, peer-reviewed papers to support its central estimates for the variables from which climate sensitivity is calculated is not supported by the evidence.

Given the importance of feedback to their forecasts, the treatment in the latest IPCC report of feedback borders on the criminal.  I have read the relevant sections and it is nearly impossible to find any kind of discussion of these issues.  A cynical mind might describe the thousands of pages of the IPCC report as the magician grabbing your attention with his left hand to hide what is in his right hand.  And what is being hidden is that … there is nothing there!  Feedback is the pivotal point on which the whole discussion of drastic carbon abatement should turn and there is nothing there. 

Monckton goes further, to point out that hidden in the IPCC numbers lies an absurdity:

if the upper estimates of each of the climate-relevant feedbacks listed in IPCC (2007) are summed, an instability arises. The maxima are –

Water vapor 1.98, lapse rate -0.58, surface albedo 0.34, cloud albedo 1.07, CO2 0.57, total 3.38 W m-2 K-1.

The equation f = (1 – bκ)-1 becomes unstable as b → κ-1 = 3.2 W m-2 K-1. Yet, if each of the individual feedbacks imagined by the IPCC is increased to less than the IPCC’s maximum, an instability or “runaway greenhouse effect” is reached.

Yet it is reliably inferred from palaeoclimatological data that no “runaway greenhouse effect” has occurred in the half billion years since the Cambrian era, when atmospheric CO2 concentration peaked at almost 20 times today’s value

Positive feedback can be weird and unstable.  If there is enough of it, processes tend to run away (e.g. nuclear fission), which is what Monckton is arguing that some of the IPCC assumptions lead to.  Even when feedback is less positive, it still can cause processes to fluctuate wildly.  In fact, it is fairly unusual for long-term stable processes like climate to be dominated by positive feedback.  Most scientists, when then meet a new process, would probably assume negative feedback until proven otherwise.  This is a particular issue in climate, where folks like Michael Mann have gone out of their way to argue that the world temperature history over the last 1000 years before man began burning fossil fuels is incredibly stable and unchanging.  If so, how can this be consistent with strong positive feedback?

Anyway, there is a lot more numerical detail in Monckton’s post if you want to dig into the equations.

I would add one thing to his analysis:  If you look at the last 100 years of history, the change in temperature given the observed change in CO2 levels comes no where close to a climate sensitivity of 3 or more, even when you assign all historical warming to CO2 rather than other effects like the sun.  In fact, as I showed in this analysis, climate sensitivity appears to be 1.2 when one assigns all past warming to CO2, and something well less than that if one accepts the sun and other effects also play a role.  These historical analyses would point to feedback that is either zero or negative rather than positive, more in line with what one would expect from complex natural systems.

You can see a discussion of many of these topics in the video below:

What He Said

John Atkinson, via Tom Nelson, mirrors many of my thoughts on climate models:

The scientists who interest me in this field are those who can draw on the experience of a lot of people who have come before them. And uniformly in these areas I find scepticism. People who write mathematical models of complex systems for a living tend to find the climate models very unconvincing. Geologists find the arguments very unconvincing. Engineers find the arguments unconvincing. And astrophysicists find the arguments unconvincing….

The climate models seem to be largely driven by over-fitting to a small sample set and positive feedback. The small sample set – at most 30 years of accurate data – might be enough to try and predict one or two years, but 50 year predictions? Ignoring the biggest effect on global warming – water vapour – is surely going to cause problems.

Positive feedback in engineering invariably results in unstable systems – so we have to ask why do most if not all of the climate models rely on it to get doomsday predictions? For the Earth to have survived as long as it has with a stable climate, through major events like ice-ages or volcanic eruptions, there is little doubt that a degree of negative climate feedback is essential.

Some General Thoughts

I have been getting a lot of new readers of late, including a number of commenters who disagree with me fairly strongly.  Welcome.  Here are some general thoughts:

  1. Excepting some ads for Viagra and cell phones, I have never and will never delete a comment on this site.  Folks are welcome to fill up the comment threads with contrary opinions. For those distrustful of the motives of skeptics, may I observe that sites like RealClimate cannot make this claim and routinely flush comments that don’t agree with the local prevailing doctrine, so make of that what you will.
  2. I almost never respond to comments in the comment thread itself.  I like to think about and digest the comments for a while, and then incorporate them or respond to them in later posts.  Trying to respond in real time in comment threads results in flame wars, not reasoned discussion. 
  3. Unlike many skeptics, I accept that atmospheric CO2 produced by man can warm the earth.  The IPCC and most climate scientists believe that the greenhouse gas effect alone may warm the earth about a degree over the rest of this century, an amount that would be a nuisance rather than catastrophic, and likely lost in the random noise of natural variations.
  4. However, I do not believe the earth’s climate is dominated by strong positive feedbacks and tipping points.  It is this feedback hypothesis in climate models that multiplies warming to 3-4-5 degrees or more over the next century.  In climate models, the catastrophe comes from feedback, not greenhouse effects, and I think this is a bad hypothesis.  Believers in catastrophic warming have an interesting problem reconciling Mann’s hockey stick, which points to incredible stability in temperatures, with a hypothesis of very high positive feedback, which should make temperatures skittish and volatile.  I also think that the hypothesis that aerosols are masking substantial amounts of warming is weak, and appears to be more wishful thinking to bail out model builders than solid science (while there is some cooling effect, the area of effect is local and shouldn’t have a substantial effect on global averages).
  5. I think the surface temperature record as embodied in the GISS analysis is a joke.  I cannot respect scientists who eschew obviously superior satellite measurements for the half-assed surface temperature record just because it doesn’t give them the answer they want to here.  The fact that the leader in fighting for surface temeprature measurement over satellites is James Hansen of NASA’s Goddard Institute for Space Studies is the ultimate dark irony.  It’s like Bill Gates campaiging for increased abacus use in schools.
  6. I have built models of complex systems for years.  I have been guilty many times of allowing seamingly reasonable assumptions to compound into meaningless results.  Unfortunately and embarassingly, I have also been guilty of tweaking, plugging, and tuning models to better match history in order to build confidence in their future predictions.  I see all too many of these same behaviors amoung climate modellers. 

Update to My Best Skeptic’s Argument

Based on a lot of comment activity to this post, I wanted to add a bit of an update.  It is sometimes hard to summarize without losing important detail, and I think I had that happen here.

Commenters are correct that positive feedback dominated systems can be stable as long as the feedback percentage is less than 100%.  By trying to get too compact in my arguments, I combined a couple of things.  First, there are many catastrophists that argue that climate IS in fact dominated by feedback over 100% — anyone who talks of "tipping points" is effectively saying this.  The argument about instability making stable processes impossible certainly applies to these folks’ logic.  Further, even positive feedback <100% makes a system highly subject to dramatic variations.  But Mann et. al. are already on the record saying that without man, global temperatures are unbelievably stable and move in extremely narrow ranges.   It is hard to imagine this to be true in a climate system dominated by positive feedback, particularly when it is beset all the time with dramatic perturbations, from volcanoes to the Maunder Minimum.

To some extent, climate catastrophists are in a bind.  If historic temperatures show a lot of variance, then a strong argument can be made that a large portion of 20th century warming is natural occilation.  If historic temperatures move only in narrow ranges, they have a very difficult time justifying that the climate is dominated by positive feedbacks of 60-80%.

The point to remember, though, is that irregardless of likelihood, the historical temperature record simply does not support assumptions of feedback much larger than zero.  Yes, time delays and lags make a small difference, but all one has to do is compare current temperatures to CO2 levels 12-15 years ago to account for this lag and one still gets absolutely no empirical support for large positive feedbacks.

Remember this when someone says that greenhouse gas theory is "Settled."  It may or may not be, but the catastrophe does not come directly from greenhouse gasses.  Alone, they cause at most nuisance warming.  The catastrophe comes from substantial positive feedback (it takes 60-80% levels to get climate sensitivities of 3-5C) which is far from settled science.

Even Shorter Version of Climate Video

After finding out about this contest, I wanted to enter.  However, having very little time, I had to work with something I already had on the shelf.  So I chose to edit this 9+ minute video critiquing catastrophic global warming forecasts to create a three minute version (per the contest rules).

I am pretty sure this is not what the folks running the contest really are looking for, but I had fun trying.   So here is my most edited effort yet, Don’t Panic — The Case Against Catastrophic Global Warming Forecasts

I had to just assert some things given the time constraints without presenting the evidence (particularly in the aerosol discussion).  The more complete 9 minute version critiquing global warming forecasts is here.   And the big boy, the 50-minute video covering a wide range of climate change topics, is here.

My Best Skeptic’s Argument

Crossposted from Coyote Blog

I began with an 85-page book.  I shortened that to a 50-minute film, and then a 9-minute film.  With that experience, I think I can now pull out and summarize in just a few paragraphs why we should not fear catastrophic global warming.  Here goes:

Climate catastrophists often argue that global warming theory is "settled science."  And they are right in one respect:  We have a pretty good understanding of how CO2 can act as a greenhouse gas and cause the earth to warm.  What is well agreed upon, but is not well communicated in the media, is that a doubling of CO2, without other effects that we will discuss in a moment, will heat the earth about 1 degree Celsius (plus or minus a few tenths).  This is not some skeptic’s hallucination — this is straight out of the IPCC third and fourth assessments.  CO2, acting alone, warms the Earth only slowly, and at this rate we would see less than a degree of warming over the next century, more of a nuisance than a catastrophe.

But some scientists do come up with catastrophic warming forecasts.  They do so by assuming that our Earth’s climate is dominated by positive feedbacks that multiply the initial warming from CO2 by a factor of three, four, five or more.  This is a key point — the catastrophe does not come from the science of greenhouse gases, but from separate hypotheses that the earth’s climate is dominated by positive feedback.  This is why saying that greenhouse gas theory is "settled" is irrelevant to the argument about catastrophic forecasts.  Because these positive feedbacks are NOT settled science.  In fact, the IPCC admits it does not even know the sign of the most important effect (water vapor), much less its magnitude.  They assume that the net effect is positive, but they are on very shaky ground doing so, particularly since having long-term stable systems like climate dominated by positive feedback is a highly improbable.

And, in fact, with the 100 or so years of measurements we have for temperature and CO2, empirical evidence does not support these high positive feedbacks.  Even if we assign all the 20th century warming to CO2, which is unlikely, our current warming rates imply close to zero feedback.  If there are other causes for measured 20th century warming other than CO2, thereby reducing the warming we blame on CO2, then the last century’s experience implies negative rather than positive feedback in the system.  As a result, it should not be surprising that high feedback-driven forecasts from the 1990 IPCC reports have proven to be way too high vs. actual experience (something the IPCC has since admitted).

However, climate scientists are unwilling to back down from the thin branch they have crawled out on.  Rather than reduce their feedback assumptions to non-catastrophic levels, they currently hypothesize a second man-made cooling effect that is masking all this feedback-driven warming.  They claim now that man-made sulfate aerosols and black carbon are cooling the earth, and when some day these pollutants are reduced, we will see huge catch-up warming.  If anything, this cooling effect is even less understood than feedback.  What we do know is that, unlike CO2, the effects of these aerosols are short-lived and therefore localized, making it unlikely they are providing sufficient masking to make catastrophic forecasts viable.  I go into several reality checks in my videos, but here is a quick one:  Nearly all the man-made cooling aerosols are in the northern hemisphere, meaning that most all the cooling effect should be there — but the northern hemisphere has actually exhibited most of the world’s warming over the past 30 years, while the south has hardly warmed at all.

In sum, to believe catastrophic warming forecasts, one has to believe both of the following:

  1. The climate is dominated by strong positive feedback, despite our experience with other stable systems that says this is unlikely and despite our measurements over the last 100 years that have seen no such feedback levels.
  2. Substantial warming, of 1C or more, is being masked by aerosols, despite the fact that aerosols really only have strong presence over 5-10% of the globe and despite the fact that the cooler part of the world has been the one without the aerosols.

Here’s what this means:  Man will cause, at most, about a degree of warming over the next century.  Most of this warming will be concentrated in raising minimum temperatures at night rather than maximum daytime temperatures  (this is why, despite some measured average warming, the US has not seen an increase of late in maximum temperature records set).  There are many reasons to believe that man’s actual effect will be less than 1 degree, and that whatever effect we do have will be lost in the natural cyclical variations the climate experiences, but we are only just now starting to understand.

To keep this relatively short, I have left out all the numbers and such.  To see the graphs and numbers and sources, check out my new climate video, or my longer original video, or download my book for free.

Update:  Commenters are correct that positive feedback dominated systems can be stable as long as the feedback percentage is less than 100%.  By trying to get too compact in my arguments, I combined a couple of things.  First, there are many catastrophists that argue that climate IS in fact dominated by feedback over 100% — anyone who talks of "tipping points" is effectively saying this.  The argument about instability making stable processes impossible certainly applies to these folks’ logic.  Further, even positive feedback <100% makes a system highly subject to dramatic variations.  But Mann et. al. are already on the record saying that without man, global temperatures are unbelievably stable and move in extremely narrow ranges.   It is hard to imagine this to be true in a climate system dominated by positive feedback, particularly when it is beset all the time with dramatic perturbations, from volcanoes to the Maunder Minimum.

To some extent, climate catastrophists are in a bind.  If historic temperatures show a lot of variance, then a strong argument can be made that a large portion of 20th century warming is natural occilation.  If historic temperatures move only in narrow ranges, they have a very difficult time justifying that the climate is dominated by positive feedbacks of 60-80%,

The point to remember, though, is that irregardless of likelihood, the historical temperature record simply does not support assumptions of feedback much larger than zero.  Yes, time delays and lags make a small difference, but all one has to do is compare current temperatures to CO2 levels 12-15 years ago to account for this lag and one still gets absolutely no empirical support for large positive feedbacks.

Remember this when someone says that greenhouse gas theory is "Settled."  It may or may not be, but the catastrophe does not come directly from greenhouse gasses.  Alone, they cause at most nuisance warming.  The catastrophe comes from substantial positive feedback (it takes 60-80% levels to get climate sensitivities of 3-5C) which is far from settled science.

All the “Catastrophe” Comes from Feedback

I had an epiphany the other day:  While skeptics and catastrophists debate the impact of CO2 on future temperatures, to a large extent we are arguing about the wrong thing.  Nearly everyone on both sides of the debate agree that, absent of feedback, the effect of a doubling of CO2 from pre-industrial concentrations (e.g. 280 ppm to 560 ppm, where we are at about 385ppm today) is to warm the Earth by about 1°C ± 0.2°C.  What we really should be arguing about is feedback.

In the IPCC Third Assessment, which is as good as any proxy for the consensus catasrophist position, it is stated:

If the amount of carbon dioxide were doubled instantaneously, with everything else remaining the same, the outgoing infrared radiation would be reduced by about 4 Wm-2. In other words, the radiative forcing corresponding to a doubling of the CO2 concentration would be 4 Wm-2. To counteract this imbalance, the temperature of the surface-troposphere system would have to increase by 1.2°C (with an accuracy of ±10%), in the absence of other changes.

Skeptics would argue that the 1.2°C is (predictably) at the high end of the band, but in the ballpark none-the-less.  The IPCC also points out that there is a diminishing return relationship between CO2 and temperature, such that each increment of CO2 has less effect on temperature than the last.  Skeptics also agree to this.  What this means in practice is that though the world, currently at 385ppm CO2, is only about 38% of the way to a doubling of CO2 from pre-industrial times, we should have seen about half of the temperature rise for a doubling, or if the IPCC is correct, about 0.6°C (again absent feedback).  This means that as CO2 concentrations rise from today’s 385 to 560 toward the end of this century, we might expect another 0.6°C warming.

This is nothing!  We probably would not have noticed the last 0.6°C if we had not been told it happened, and another 0.6°C would be trivial to manage.  So, without feedback, even by the catastrophist estimates at the IPCC, warming from CO2 over the next century will not rise about nuisance level.  Only massive amounts of positive feedback, as assumed by the IPCC, can turn this 0.6°C into a scary number.  In the IPCC’s words:

To counteract this imbalance, the temperature of the surface-troposphere system would have to increase by 1.2°C (with an accuracy of ±10%), in the absence of other changes. In reality, due to feedbacks, the response of the climate system is much more complex. It is believed that the overall effect of the feedbacks amplifies the temperature increase to 1.5 to 4.5°C. A significant part of this uncertainty range arises from our limited knowledge of clouds and their interactions with radiation. …

So, this means that debate about whether CO2 is a greenhouse gas is close to meaningless.  The real debate should be, how much feedback can we expect and in what quantities?  (By the way, have you ever heard the MSM mention the word "feedback" even once?)   And it is here that the scientific "consensus" really breaks down.  There is no good evidence that feedback numbers are as high as those plugged into climate models, or even that they are positive.  This quick analysis demonstrates pretty conclusively that net feedback is probably pretty close to zero.  I won’t go much more into feedback here, but suffice it to say that climate scientists are way out on a thin branch in assuming that a long-term stable process like climate is dominated by massive amounts of positive feedback.  I discuss and explain feedback in much more detail here and here.

Update:  Thanks to Steve McIntyre for digging the above quotes out of the Third Assessment Report.  I have read the Fourth report cover to cover and could not find a single simple statement making this breakdown of warming between CO2 in isolation and CO2 with feedbacks.  The numbers and science has not changed, but they seem to want to bury this distinction, probably because the science behind the feedback analysis is so weak.

Single Best Reason Not to Panic About Climate

When I have only 60 seconds to explain why I dont think man-made global warming will be catastrophic enough to warrant massively expensive CO2 abatement programs, this is my argument:

  1. CO2 does indeed absorb selected wavelengths of readiation returning to space from earth, having a warming effect on the atmosphere.  However, this effect is a diminishing return — each successive increment of CO2 concentrations will have a much smaller effect on temperatures than the previous increment.  Eventually, CO2 becomes nearly saturated in its ability to absorb radiation.  The effect is much like painting a red room with white paint.  The first coat covers a lot of red but some still shows through.  Each additional coat will make the room progressively whiter, but each successive coat will have a less noticeable effects than the previous coat, until the room is just white and can’t get any whiter  (the "layers" of CO2 are shown in pink below)
  2. First_layer  Fourth_layer_2

  3. In the 20th century, the UN IPCC claims Earth’s surface temperatures have increased by about a 0.6 degree Celsius (though there are some good reasons to think that biases in the installation of temperature instruments have exaggerated this apparent increase).  To be simple (and generous), let’s assume all this 0.6C increase is due to man-made greenhouse gasses.  Some may in fact have been due to natural effects, but some may also have been masked by man-made sulfate aerosols, so lets just call man-made warming to be 0.6C. 
  4. Since the beginning of the industrial revolution, it is thought that man has increased atmospheric CO2 concentrations from 0.028% of the atmosphere to 0.038% of the atmosphere.  Since scientists often talk about the effect of a doubling of CO2, this historic rise in CO2 is 36% of a doubling.
  5. Using simple math, we see that if temperatures have risen 0.6C due to 36% of a doubling, we might expect them to rise by 1.67C for a full doubling to 0.056% of the atmosphere.  But this assumes that the rise is linear — and we already said (and no one denies) that it is in fact a diminishing return relationship.  Using a truer form of the curve, a 0.6C historic rise for 36% of a doubling implies a full doubling would raise temperatures by about 1.2C, or about 0.6C more than we have seen to date (see chart below).   This means that the magnitude of global warming in the next century might be about what we have seen (and apparently survived) since 1900.
  6. Obviously, there is some kind of disconnect here.  The IPCC predicts temperature increases in the next century of 4-8 degrees C.  Big difference.  In fact, the IPCC predicts we will get a 0.5C rise in just 20 years, not 70-100.  Whereas we derived a climate sensitivity of 1.2 from empirical data, they arrive at numbers between 3 and 4 or even higher for sensitivity.  The chart below shows that to believe sensitivity is 3, we would have to have seen temperature rises due to man historically of 1.5C, which nobody believes. 

    So how do they get accelerating temperatures from what they admit to be a diminishing return relation between CO2 concentration and temperature? And for which there is no empirical evidence?  Answer:  Positive feedback.

  7. 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.  Negative feedback is a ball in the bottom of a bowl; positive feedback is a ball perched precariously at the time of a mountain. 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" like the ball rolling down the hill.  Nuclear fission, for example, is a positive feedback process.  We should be happy there are not more positive feedback processes on our planet.  Current man-made global warming theory, however, asserts that our climate is dominated by positive feedback.  The IPCC posits that a small increase in temperature from CO2 is multiplied 2,3,4 times or more by positive feedbacks like humidity and ice albedo.
  8. There are three problems with these assumptions about positive feedback.  One, there is no empirical evidence at all that positive feedbacks in climate dominate negative feedbacks.   The 20th century temperature numbers we discussed above show no evidence of these feedbacks.  Since we used empirical numbers to calculate the sensitivity, it is already net of any feedbacks. Two, the long-term temperature record demonstrates that positive feedbacks can’t dominate, because past increases in temperature and CO2 have not run away.  And three, characterizations of stable natural processes as being dominated by positive feedback should offend the intuition and common sense of any scientist.
  9. An expected 21st century increase of 0.5 or even 1 degree C does not justify the massive imposed government interventions that will be costly both in dollars and lost freedoms.  In particular, the developing world will be far better off hotter by a degree and richer than it would be cooler and poorer.  This is particularly true since sources like an Inconvenient Truth wildly exaggerate the negative effects of global warming.  There is no evidence tornadoes or hurricanes or disease or extinction are increasing as the world warms, and man-made warming advocates generally ignore any potential positive effects of warming.  As to rising sea levels, the IPCC predicts only a foot and a half of sea level rise even with 4 or more degrees of warming.  Sea level rise from a half to one degree of warming would be measured at most in inches.

OK, so that was more than 60 seconds.  But it is a lot less than 80 pages.  There is a lot of complexity behind every one of these statements.  If you are intrigued, or at least before you accuse me of missing something critical, see my longer paper on global warming skepticism first, where all these issues and much more (yes, including tree rings and cosmic rays) are discussed in more depth.  You can also watch my free climate movie.

More Ways to View My Climate Video

There has been a lot of interest in my new climate video.  Already we have nearly 450 1400 views at Google video and over 200 800 downloads of the video.  I am now releasing the video on DVD and through YouTube.

I have had several requests for a DVD version rather than an online version or file.  For a limited time, through December 31, 2007, I will send a DVD of my video What is Normal?  A Critique of Catastrophic Man-Made Global Warming Theory to anyone who sends me a stamped self-addressed envelope.  The DVD plus a standard CD mailer weigh about 3.3 OZ, so you will need $1.31 postage in the US.  Send your request to "Climate Video, c/o Warren Meyer, 11811 N. Tatum Blvd #4095, Phoenix, AZ, 85253"

Also, in response to popular demand, I have release the video on YouTube.  YouTube requires that all videos be under 10 minutes, so I have broken the film into six parts.  If you want to just preview a portion, the second half of the fourth film and the first half of the fifth are probably the most critical.

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 still 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.

Climate Video Release!

My first climate movie, What is Normal?  A Critique of Catastrophic Man-Made Global Warming Theory is now available for free download.  If you have the bandwidth, I encourage you to download the full 640×480 version as Windows Media Video, but be forewarned that the file is 258MB.  This is actually a pretty small file for a 50+ minute movie, and the full resolution version looks much nicer than the streaming version.

Right-Click Here to Download Climate Movie in Full Resolution

Update:  Right-Click here for full resolution 144MB .mov quicktime version of Climate Movie

Make sure you turn up your volume — I think I recorded this with a pretty low audio level.

If you are bandwidth-challenged, or you can’t view a .WMV file, you may stream the video from Google video or download a reduced resolution version here.  Unfortunately, to make the video stream effectively, the resolution is cut to 320×240, but having watched it, it actually still looks surprisingly good streamed. 

Note, on the streaming version, the video stutters between the 12 and 17 second marks in the movie, but runs fine after that.  By the way, thanks to all the commenters who gave me some good alternatives to using my own fairly week narration voice.  I decided for this first release I wanted to see what I could achieve with a pure solo effort.  Many thanks to Adobe Premier Elements, which made this effort possible.

Finally, you can stream the reduced resolution Google video version below:

New Global Warming Video Release

Please check back Monday morning, as I will be releasing my new video, "What is Normal:  A Critique of Catastrophic Man-Made Global Warming Theory."  As with my global warming book, which began as a ten page summary and ended up as an 85-page manuscript, the video started at a goal of 15 minutes and eventually ended up at 50 minutes.  However, unlike other global warming-related videos I will not name, it is all climate science, with no self-congratulatory segments on my childhood.

Duh

From Megan McArdle:

Matt may be right that I haven’t harangued people about climate change recently, so here goes: dude, if you’re still a climate change skeptic, it’s time for a rethink. When the science correspondent for Reason magazine comes over to the reality of anthropogenic global warming, it’s safe to say that the skeptics have lost the debate. Not only the vast majority of the scientific community, but even most of the hard-core skeptics at conservative magazines, have abandonned the hope that we are not warming up the climate.

There’s still debate about the effects of the warming, and what we should do about it. But there’s not much question that it’s happening.

Duh.  The vision of the skeptic community denying that the world is warming at all is a straw man created by the climate catastrophists to avoid arguing about the much more important point in her second paragraph.  What I can’t understand is McArdle’s, and many intelligent people I meet, seeming unintrest in the degree of man-made impact.

The chief debate really boils down to those of us who think that climate sensitivity to CO2 is closer to 1C (ie the degrees the world will warm with a doubling of CO2 concentrations from pre-industrial levels) and those who think that the sensitivity is 3-5C or more.  The lower sensitivity implies a warming over the next century of about a half degree C, or about what we saw in the last century.  The higher numbers represesent an order of magnitude more warming in the next century.  The lower numbers imply a sea level rise measured in inches.  The higher numbers imply a rise of 1-2 feet  (No one really know where Al Gore gets his 20 foot prediction in his movie).  The lower numbers we might not even notice.  The higher numbers will certainly cause problems.

The other debate is whether the cost of CO2 abatement should even be considered.  I have talked to many people who say the costs are irrelevent – Gaia must come first.  But steps to make any kind of dent in CO2 production with current technologies will have a staggering impact on the world economy.  For example, there are a billion Asians poised to finally to enter the middle class who we will likely consign back to poverty with an aggresive CO2 reduction program.  With such staggering abatement costs, it matters how bad the effects of man-made global warming will be. 

There are many reasons a 1.0 climate sensivity is far more defensible than the higher sensitivities used by catastrophists.  My argument a lower climate sensitivity and therefore a less aggresive posture on CO2 is here.  Cross-posted at Coyote Blog.

Update: Sure, we skeptics debate the degree of past warming, but it really can’t be denied the earth is warmer than 100 years ago.  The problem catastrophists have with defending their higher climate sensitivities is that these sensitivities imply that we should have seen much more warming over the past 100 years, as much as 1.5C or more instead of about 0.6C.  These scientists have a tendency to try to restate historical numbers to back their future forecast accuracy.  We skeptics fight them on this, but it does not mean we are trying to deny warming at all, just make sure the science is good as to the magnitude.

One other thought – everyone should keep two words in mind vis a vis CO2 and its effect on temperature:  Diminishing Return.  Each new molecule of CO2 has less impact on temperature than the last one.  Only by positing a lot of weird, unlikely, and unstable positive feedbacks in the climate can scientists reach these higher sensitivity numbers (more here).  A good economist would laugh if they understood the assumptions that were being made in the catastrophic forecasts that are being used to influence government action.

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:

Sensitivity1

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:

Sensitivity2

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.