2011-01-18 13:05:42Monckton Myth #4: Climate Sensitivity
John Cook


Climate sensitivity is a measure of the change in global temperature if atmospheric CO2 was doubled. If there were no climate feedbacks, warming from doubled CO2 would be around 1°C. There are many lines of evidence that indicate climate sensitivity is around 3°C. In other words, feedbacks amplify the initial warming from rising CO2. However, Christopher Monckton disputes this. In Monckton's response to Steketee's article, he claims:

"Most climate scientists have not studied the question of how much warming a given increase in CO2 concentration will cause: therefore, whatever opinion they may have is not much more valuable than that of a layman. Most of the few dozen scientists worldwide whom Prof. Richard Lindzen of MIT estimates have actually studied climate sensitivity to the point of publication in a learned journal have reached their results not by measurement and observation but by mere modeling. The models predict warming in the range mentioned by Mr. Steketee, but at numerous crucial points the models are known to reflect the climate inaccurately."

Monckton's conceit (here and in numerous other presentations) is that estimates of high climate sensitivity come from models, while an estimate of low climate sensitivity, courtesy of Richard Lindzen, comes from measurements and observations. This is a false portrayal of the state of the science. There are many determinations of climate sensitivity based on measurements and observations. In fact, several studies use more complete satellite observations than those used by Lindzen and find high climate sensitivity.

To calculate climate sensitivity, Lindzen looks at sea surface temperature in the tropics along with satellite measurements of outgoing radiation (Lindzen et al 2009).  The change in outward radiation tells us how climate responds to changing temperature. Their analysis found that when it gets warmer, more outgoing radiation escapes to space which has a cooling effect. Lindzen concluded that negative feedbacks actually suppress surface warming and our planet has a low climate sensitivity of about 0.5°C.

However, a number of peer-reviewed papers have exposed fatal flaws in Lindzen's methods (Trenberth et al 2010, Murphy 2010, Chung et al 2010). What Lindzen is trying to do is calculate global climate sensitivity from tropical data. The tropics are not a closed system - a great deal of energy is exchanged between the tropics and subtropics. To properly calculate global climate sensitivity, global observations are required. Several studies have performed the same analysis using near-global data. One study found that small changes in the heat transport between the tropics and subtropics can swamp the tropical signal. They conclude that climate sensitivity must be calculated from global data (Murphy 2010).

Another study reproduced Lindzen's analysis and compared it to results using near-global data (Chung et al 2010). The near-global data find high climate sensitivity and the authors conclude that the tropical ocean is not an adequate region for determining global climate sensitivity. So Monckton's characterisation that measurements find low climate sensitivity does not give you the full picture. In actuality, Lindzen's data covers only part of the globe and more complete observations find high climate sensitivity.

There is another important reason why we can be confident that negative feedbacks aren't our get-out-of-jail-free card to rescue us from global warming. Measurements of past climate change have not found negative feedback suppressing climate change. On the contrary, what we find in the Earth's past is dramatic climate change - positive feedbacks amplifying changes in temperature. A multitude of papers looking at different periods in Earth's history independently and empirically converge on a consistent answer - climate sensitivity is around 3°C implying net positive feedback.

Various estimates of climate sensitivity

Figure 1: Various estimates of climate sensitivity (Knutti and Hegerl 2008).

Monckton's depiction that high climate sensitivity is based on models rather than observation is false. A number of lines of evidence all paint a consistent picture - positive feedbacks will amplify the warming caused by greenhouse gas emissions.
2011-01-18 13:11:30A few notes re this post
John Cook


Firstly, there are two blog posts before I post this. Tuesday afternoon, a guest post from Mila about another new feature at zvon.org (the man is truly a machine).

Then Wednesday morning, I'd like to post two new climate graphics taken from Robert's Monckton Myth #2.

So I'll publish this Wednesday afternoon - generally I'm giving each blog post 12 hours to breath. Dana's Myth #5 can then come on Thursday sometime.

Secondly, I created a new climate graphic for this post - various estimates of climate sensitivity. I took Knutti's graph and split it into two columns as that long tall graph was just too much of a pain for blog posts, too tall. Is this graphic clear? Does having two columns make it confusing?

Thirdly, in Monckton's climate sensitivity point, he also spouted about the tropospheric hot spot and something about evaporation. I elected not to refute those although his disinformation about the hot spot was sooo tempting. I wanted to keep the blog post focused. This is not about rebutting every point he makes but pointing out his most egregious errors and also selecting the errors that are clearest - that enable us to point out how Monckton misleads without getting bogged down in technical details. Eg - people need to learn how Monckton misleads just as much as they need to learn the science.

2011-01-18 15:55:27
Rob Painting

Looks good. I don't find the graph confusing but then YMMV. You're right to keep the post focused, The beauty of the Monckton mash is that it only takes a word or phrase to create FUD, and if you attempt to correct every last detail you end up writing a novella.

You could also have split the post into two parts if you were that tempted. 

2011-01-18 15:56:02comments
Dana Nuccitelli

Looks good.  It might be worth mentioning that Trenberth et al. (2010) soundly refuted Lindzen and Choi.  And that their low climate sensitivity value was biased by the endpoints they selected in their analysis, among other errors.

"Monckton's conceit [is "conceit" the right word here?] (here and in numerous other presentations) is that estimates of high climate sensitivity come from models [insert comma here] while an estimate"

I think you're more disciplined than me.  When I see an incorrect statement, I have a hard time letting it slide :-)

Regarding the figure, I like that it's not so long and narrow anymore.  It is harder to read in two columns, but I'm not sure how to improve it.

2011-01-18 16:07:04Graphic
Daniel Bailey
Daniel Bailey

I understand why you broke up the graphic as you did, but some will find it confusing.  What is needed is some type of a vertical separator to divide left from right.

Else those who don't know left from right may think the right is a continuation of the left, but not in how you intend.


Plus, I thought the strength of the Knutti figure was the accompanying color-coded uncertainties associated with it.

2011-01-18 16:19:53Mentioning Trenberth 2010
John Cook


Dana, the observant will notice I copied and pasted from my Lindzen rebuttal to create this blog post (why did you think I was so quick to volunteer for this topic). In my original rebuttal, Trenberth featured heavily. But for this blog post, I pared it down to just the tropic vs near-global data. It's more conceptual and intuitive rather than getting bogged down in technical details. However, I may add a link to the Lindzen rebuttal for more details.

Daniel, my version of Knutti's graph is quite simplified - all that color coding is bewildering for the untrained so frankly, it's noise from a communication point of view. Every graphic needs to tell a compelling story - the story here is that all these different methods paint a consistent picture.

2011-01-18 16:50:12Slow feedbacks
James Wight

This is a bit off-topic as you’re talking about fast-feedback senstivity, but one example of a climate model inaccuracy is that the slow feedback from ice sheets is already occurring faster than the models predict. Remember the models predicted the ice sheets would actually grow during this century!

I think the two columns in the graph are confusing. I mean, I’m not confused because I’m already familiar with the one-column version, but if I wasn’t I’d probably be wondering why there are two columns. You could use the original and have the text wrap around it like in the “climate’s changed before” rebuttal.

Also, “more outgoing radiation escaped to space which had a cooling effect” should read “more outgoing radiation escapes to space which has a cooling effect”.
2011-01-18 17:11:52
Ari Jokimäki

I think it's worth mentioning that Lindzen has been thoroughly debunked, because I think it's probably one of the worst peer-reviewed papers I have seen. Your text currently makes it seem that their study would have some kind of merit otherwise but they just are not doing a global analysis, when in reality their study fails just about in all imaginable ways.
2011-01-18 17:24:10Okay, I've added the Trenberth reference and toughened up the text
John Cook


Lindzen doesn't get quite the free pass I was giving him before.

James, also made your text change, thanks

2011-01-18 18:16:52
Rob Painting
So is Lindzen the next target?. He says a lot of ridiculous things in the press (and in congressional testimony!) and rarely seems held to account.
2011-01-19 01:00:05
Mark Richardson

You should probably link to the LC09 rebuttal. Their very 'specific' choices of time period were very suspicious and the method's sensitivity show that it's not very rigorous.



The method might be worthwhile, but their methodology and data selection is so shit that I'm surprised it hasn't been pulled by the editors, or at least forced them to change the conclusions to 'our method constrains climate sensitivity to between 0.5 and 5 C' or whatever it actually does do.

2011-01-19 01:25:06

It's also worth pointing out that he makes lots of off-hand remarks in his WSJ editorials that he would never try to get away with in his journal articles.
2011-01-19 04:18:06link to rebuttal
Dana Nuccitelli
I agree that it's at least worth mentioning that there were a number of significant errors in LC09, and link to the rebuttal for further details.
2011-01-19 09:59:49Published
John Cook

Posted this Wednesday morning. Dana, perhaps give it a day or so before posting #5. I have one post about Robert's All Series graphic. Will post it Wednesday night - give Myth #4 a good 12 hours to breath.
2011-01-19 10:02:24roger that
Dana Nuccitelli
Yeah I'm in no rush.  Maybe tomorrow sometime for #5.