Monthly Archives: January 2011

My Favorite Topic, Feedback

I have posted on this a zillion times over here, and most of you are up to speed on this, but I posted this for my Coyote Blog readers and thought it would be good to repost over here.

Take all the psuedo-quasi-scientific stuff you read in the media about global warming.  Of all that mess, it turns out there is really only one scientific question that really matters on the topic of man-made global warming: Feedback.

While the climate models are complex, and the actual climate even, err, complexer, we can shortcut the reaction of global temperatures to CO2 to a single figure called climate sensitivity.  How many degrees of warming should the world expect for each doubling of CO2 concentrations  (the relationship is logarithmic, so that is why sensitivity is based on doublings, rather than absolute increases — an increase of CO2 from 280 to 290 ppm should have a higher impact on temperatures than the increase from, say, 380 to 390 ppm).

The IPCC reached a climate sensitivity to CO2 of about 3C per doubling.  More popular (at least in the media) catastrophic forecasts range from 5C on up to about any number you can imagine, way past any range one might consider reasonable.

But here is the key fact — Most folks, including the IPCC, believe the warming sensitivity from CO2 alone (before feedbacks) is around 1C or a bit higher (arch-alarmist Michael Mann did the research the IPCC relied on for this figure).  All the rest of the sensitivity between this 1C and 3C or 5C or whatever the forecast is comes from feedbacks (e.g. hotter weather melts ice, which causes less sunlight to be reflected, which warms the world more).  Feedbacks, by the way can be negative as well, acting to reduce the warming effect.  In fact, most feedbacks in our physical world are negative, but alarmist climate scientists tend to assume very high positive feedbacks.

What this means is that 70-80% or more of the warming in catastrophic warming forecasts comes from feedback, not CO2 acting alone.   If it turns out that feedbacks are not wildly positive, or even are negative, then the climate sensitivity is 1C or less, and we likely will see little warming over the next century due to man.

This means that the only really important question in the manmade global warming debate is the sign and magnitude of feedbacks.  And how much of this have you seen in the media?  About zero?  Nearly 100% of what you see in the media is not only so much bullshit (like whether global warming is causing the cold weather this year) but it is also irrelevant.  Entirely tangential to the core question.  Its all so much magician handwaving trying to hide what is going on, or in this case not going on, with the other hand.

To this end, Dr. Roy Spencer has a nice update.  Parts are a bit dense, but the first half explains this feedback question in layman’s terms.  The second half shows some attempts to quantify feedback.  His message is basically that no one knows even the sign and much less the magnitude of feedback, but the empirical data we are starting to see (which has admitted flaws) points to negative rather than positive feedback, at least in the short term.  His analysis looks at the change in radiative heat transfer in and out of the earth as measured by satellites around transient peaks in ocean temperatures (oceans are the world’s temperature flywheel — most of the Earth’s surface heat content is in the oceans).

Read it all, but this is an interesting note:

In fact, NO ONE HAS YET FOUND A WAY WITH OBSERVATIONAL DATA TO TEST CLIMATE MODEL SENSITIVITY. This means we have no idea which of the climate models projections are more likely to come true.

This dirty little secret of the climate modeling community is seldom mentioned outside the community. Don’t tell anyone I told you.

This is why climate researchers talk about probable ranges of climate sensitivity. Whatever that means!…there is no statistical probability involved with one-of-a-kind events like global warming!

There is HUGE uncertainty on this issue. And I will continue to contend that this uncertainty is a DIRECT RESULT of researchers not distinguishing between cause and effect when analyzing data.

If you find this topic interesting, I recommend my video and/or powerpoint presentation to you.

A Thought on “Short Term”

One interesting fact is that alarmists have to deal with the lack of warming or increase in ocean heat content over the last 12 years or so.  They will argue that this is just a temporary aberration, and a much shorter time frame than they are working on.    Let’s think about that.

Here is the core IPCC argument:  for the period after 1950, they claim their computer models cannot explain warming patterns without including a large effect from anthropogenic CO2.  Since almost all the warming in the latter half of the century really occurred between 1978 and 1998, the IPCC core argument boils down to “we are unable to attribute the global temperature increase in these 20 years to natural factors, so it must have been caused by man-made CO2.”  See my video here for a deeper discussion.

In effect, the core IPCC conclusions were really based on the warming over the 20 years from 1978-1998.  There was never any implication that their models couldn’t explain, say, the 1930′s or the 1970′s without manmade CO2.

So while 12 years is admittedly short compared to many natural cycles in climate, and might be considered a dangerously short period to draw conclusions from, it is fairly large compared to the 20 year period that drove the IPCC conclusions.

Here is where we stand:  The IPCC models supposedly cannot explain the 20 year period from 1978-1998 without factoring in a high climate sensitivity to CO2.  However, I would venture to guess that, prior to tweaking, the IPCC models cannot explain the 12 year period from 1998-2011 while still factoring in a high climate sensitivity to CO2.

Postscript:  I suppose the IPCC would scream “aerosols,” but even putting aside the equivocal and sometimes offsetting effects of aerosols and black carbon, I do not think one could reasonably argue their effect was much greater in one period than the other.

Climate Science Process Explained

Normally, when I cite the above as the process, I get grief from folks who say I am mis-interpreting things, as usually I am boiling a complex argument down to this summary.   The great thing about alarmist Trenberth’s piece is that no interpretation is necessary.   He outlines this process right in a single paragraph.  I will label the four steps above

Given that global warming is “unequivocal” [1], to quote the 2007 IPCC report [2], the null hypothesis should now be reversed, thereby placing the burden of proof on showing that there is no human influence [3]. Such a null hypothesis is trickier because one has to hypothesize something specific, such as “precipitation has increased by 5%” and then prove that it hasn’t. Because of large natural variability, the first approach results in an outcome suggesting that it is appropriate to conclude that there is no increase in precipitation by human influences, although the correct interpretation is that there is simply not enough evidence (not a long enough time series). However, the second approach also concludes that one cannot say there is not a 5% increase in precipitation. Given that global warming is happening and is pervasive, the first approach should no longer be used. As a whole the community is making too many type II errors [4].

Are you kidding me — if already every damn event in the tails of the normal distribution is taken by the core climate community as a proof of their hypothesis, how is there even room for type II errors?  Next up — “Our beautiful, seasonal weather — proof of global warming?”

Remember that the IPCC’s conclusion of human-caused warming was based mainly on computer modelling.  The IPCC defenders will not admit this immediately, but press them hard enough on side arguments and it comes down to the models.

The summary of their argument is this:  for the period after 1950, they claim their computer models cannot explain warming patterns without including a large effect from anthropogenic CO2.  Since almost all the warming in the latter half of the century really occurred between 1978 and 1998, the IPCC core argument boils down to “we are unable to attribute the global temperature increase in these 20 years to natural factors, so it must have been caused by man-made CO2.”  See my video here for a deeper discussion.

This seems to be a fairly thin reed.  After all, it may just be that after only a decade or two of serious study, we still do not understand climate variability very well, natural or not.  It is a particularly odd conclusion when one discovers that the models ignore a number of factors (like the PDO, ENSO, etc) that affect temperatures on a decadal scale.

We therefore have a hypothesis that is not based on observational data, and where those who hold the hypothesis claim that observational data should no longer be used to test their hypothesis.    He is hilarious when he says that reversing the null hypothesis would make it trickier for his critics.  It would make it freaking impossible, as he very well knows.  This is an unbelievingly disingenuous suggestion.  There are invisible aliens in my closet Dr. Trenberth — prove me wrong.  It is always hard to prove a negative, and impossible in the complex climate system.  There are simply too many variables in flux to nail down cause and effect in any kind of definitive way, at least at our level of understanding  (we have studied economics much longer and we still have wild disagreements about cause and effect in macroeconomics).

He continues:

So we frequently hear that “while this event is consistent with what we expect from climate change, no single event can be attributed to human induced global warming”. Such murky statements should be abolished. On the contrary, the odds have changed to make certain kinds of events more likely. For precipitation, the pervasive increase in water vapor changes precipitation events with no doubt whatsoever. Yes, all events! Even if temperatures or sea surface temperatures are below normal, they are still higher than they would have been, and so too is the atmospheric water vapor amount and thus the moisture available for storms. Granted, the climate deals with averages. However, those averages are made up of specific events of all shapes and sizes now operating in a different environment. It is not a well posed question to ask “Is it caused by global warming?” Or “Is it caused by natural variability?” Because it is always both.

At some level, this is useless.   The climate system is horrendously complex.  I am sure everything affects everything.  So to say that it affects the probability is a true but unhelpful statement.   The concern is that warming will affect the rate of these events, or the severity of these events, in a substantial and noticeable way.

It is worth considering whether the odds of the particular event have changed sufficiently that one can make the alternative statement “It is unlikely that this event would have occurred without global warming.” For instance, this probably applies to the extremes that occurred in the summer of 2010: the floods in Pakistan, India, and China and the drought, heat waves and wild fires in Russia.

Did Your SUV Cause the Earthquake in Haiti?

The other day, environmental blog the Thin Green Line wrote:

At the American Geophysical Union meeting late last month, University of Miami geologist Shimon Wdowinski argued that the devastating earthquake a year ago may have been caused by a combination of deforestation and hurricanes (H/T Treehugger). Climate change is spurring more, stronger hurricanes, which are fueled by warm ocean waters….

The 2010 disaster stemmed from a vertical slippage, not the horizontal movements that most of the region’s quakes entail, supporting the hypothesis that the movement was triggered by an imbalance created when eroded land mass was moved from the mountainous epicenter to the Leogane Delta.

I have heard this theory before, that landslides and other surface changes can trigger earthquakes.  Now, I am not expert on geology — it is one of those subjects that always seems like it would be interesting to me but puts me in a coma as soon as I dive into it.   I almost failed a pass-fail geology course in college because in the mineral identification section, all I could think to say was “that’s a rock.”

However, I do know enough to say with some confidence that surface land changes may have triggered but did not cause the earthquake.  Earthquakes come from large releases of stored energy, often between plates and faults.  It’s remotely possible land surface changes trigger some of these releases, but in general I would presume the releases would happen at some point anyway.  (Steven Goddard points out the quake was 13km below the surface, and says “It is amazing that anyone with a scientific background could attempt to blame it on surface conditions.”)

The bit I wanted to tackle was the Thin Green Line’s statement that “Climate change is spurring more, stronger hurricanes.”   This is a fascinating statement I want to attack from several angles.

First, at one level it is a mere tautology.  If we are getting more hurricanes, then by definition the climate has changed.   This is exactly why “global warming” was rebranded into “climate change,” because at some level, the climate is always changing.

Second, the statement is part of a fairly interesting debate on whether global warming in general will cause more hurricanes.  Certainly hurricanes get their power from warm water in the oceans, so it is not unreasonable to hypothesize that warmer water would lead to more, stronger hurricanes.  It turns out the question, as are most all questions in the complex climate, is more complicated than that.  It may be hurricanes are driven more by temperature gradients, rather than absolute temperatures, such that a general warming may or may not have an effect on their frequency.

Third, the statement in question, as worded, is demonstrably wrong.  If he had said “may someday spur more hurricanes,” he might have been OK, but he said that climate change, and by that he means global warming, is spurring more hurricanes right now.

Here is what is actually happening (paragraph breaks added)

2010 is in the books: Global Tropical Cyclone Accumulated Cyclone Energy [ACE] remains lowest in at least three decades, and expected to decrease even further… For the calendar year 2010, a total of 46 tropical cyclones of tropical storm force developed in the Northern Hemisphere, the fewest since 1977. Of those 46, 26 attained hurricane strength (> 64 knots) and 13 became major hurricanes (> 96 knots).

Even with the expected active 2010 North Atlantic hurricane season, which accounts on average for about 1/5 of global annual hurricane output, the rest of the global tropics has been historically quiet. For the calendar-year 2010, there were 66-tropical cyclones globally, the fewest in the reliable record (since at least 1970) The Western North Pacific in 2010 had 8-Typhoons, the fewest in at least 65-years of records. Closer to the US mainland, the Eastern North Pacific off the coast of Mexico out to Hawaii uncorked a grand total of 8 tropical storms of which 3 became hurricanes, the fewest number of hurricanes since at least 1970.

Global, Northern Hemisphere, and Southern Hemisphere Tropical Cyclone Accumulated Energy (ACE) remain at decades-low levels.

The source link has more, and graphs of ACE over the last several decades (ACE is a sort of integral, combining the time-average-strength of all hurricanes during the year.  This is a better metric than mere counts and certainly better than landfall or property damage metrics).

So, normally I would argue with alarmists that correlation is not causation.   There is no point in arguing about causation, though, because the event he claims to have happened (more and stronger hurricanes) did not even happen.  The only way he could possibly argue it (though I am pretty sure he has never actually looked at the hurricane data and simply works from conventional wisdom in the global warming echo chamber) is to say that yes, 2010 was 40-year low in hurricanes, but it would have been even lower had it not been for global warming.  This is the Obama stimulus logic, and is just as unsupportable here as it was in that context.

Postscript: By the way, 2010 was probably the second warmest year in the last 30-40 years and likely one of the 5-10 warmest in the last century, so if warming was going to be a direct cause of hurricanes, it would have been in 2010.    And yes, El Ninos and La Ninas and such make it all more complicated.  Exactly.  See this post.