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Andrew Dessler’s Climate Sensitivity Lecture: Some Observations

By Robert Bradley Jr. -- March 20, 2019

“With the boom of carbon-based energy in the US and globally, in fact, it is game-set-and-match Fossil Fuels given the logarithmic effect of GHG forcing.”

“I left the Rice University climate talk… hardly dissuaded from my prior conclusion that [Professor Dessler] is a deep ecologist engaging in half-truths for a cause. That he is not above ‘lawyering’ to present a black-and-white case for climate alarmism.”

Earlier this month,  I attended a lecture by the certain climate alarmist, Andrew Dessler, atmospheric scientist at Texas A&M University. In a recent Houston Chronicle op-ed,  “Why the Green New Deal Makes Me Hopeful About Climate Change,” Dessler stated:

If we don’t take action, unchecked greenhouse-gas emissions would lead to global-average warming over this century of 5 degrees Fahrenheit to 9 degrees Fahrenheit…. This warming is as certain as death and taxes.

And in a tweet from November of last year:

If “some humans survive” is the only thing we care about, then climate change is a non-issue. I think it’s certain that “some” humans will survive almost any climate change. They may be living short, hard lives of poverty, but they’ll be alive.

Indeed, this activist professor is the alarmist’s alarmist.


The Rice University lecture, Adventures in estimating climate sensitivity, was described as follows:

Climate sensitivity (usually defined as the equilibrium warming in response to doubled CO2) is one of the most important and uncertain parameters in climate science.  I will review the history of estimates of the quantity and explain why internal variability makes it hard to estimate this quantity from observations.  I will then show a new estimate that uses observations of internal variability of the climate system and which is less impacted by internal variability.  Our analysis yields an estimate that ECS is likely 2.4-4.6 K.

While open to the public, I might have been the only non-university person there. It was almost all students who were evidently taking the class for credit.

Dessler is a high-sensitivity believer. His talk covered the ABC’s of radiative forcing and how a doubling of CO2 in equilibrium results in about 1.2° Celsius (2.2°F) of warming. He then got into the (strongly positive) feedback effects from this initial warming (water vapor, lost ice, less low clouds) that result in the “canonical” IPCC warming range of 1.5°C – 4.5°C.

His most recent coauthored journal article produces a midpoint of 3.3°C with a range of 2.4°C to 4.6°C. (He did not mention how this compared to measured out-the-window, recent-decade warming.)

Professor Dessler then reviewed the IPCC physical-science reports. The last report (5th Assessment: 2013) dropped the bottom of the range from 2°C to 1.5°C, much to the delight of “the skeptics” (he did not use the term “denier,” thankfully, much less the term lukewarmers, as in skeptics of climate alarmism). But Dessler expects the bottom to go back up to 2°C in the next IPCC physical-science report (6th Assessment: 2021), with the high-end remaining the same or perhaps falling a notch.

The more-you-know-the-more-you-do-not-know phase of climate science is coming to a close, Dessler stated. Theory and models are well-enough known and testable with just about everything that needs to be measured being so. (As in his books, Dessler does not question climate models or mention things such as fudge factors, quite unlike his senior colleague at Texas A&M, Gerald North.)

Question & Answer

I posed the second question in the one-hour class. I recalled a Richard Kerr article in Science magazine coming out of the elevated El Nino 1998 that said that temperatures would drop for a few years but resume their rapid ascent. (Kerr in 2009, furthermore, made the prediction that the warming “pause” was ready to turn into a “jolt.”)  I also recalled for the group what alarmist Kevin Trenberth said about the “travesty” of not being able to explain the missing warming.

I then mentioned the current pause or hiatus, a phenomenon that Dessler attributes to natural variability. Where might the missing heat go, I asked. Could Richard Lindzen’s Iris Effect be partly right whereby the heat escapes from the tropics? Or could the heat be long lost in the deep ocean?

Dessler politely responded that the world was still warming and that the Iris Effect (or hypothesis) was theoretically problematic and, in fact, did not have any data behind it. (The Wikipedia entry suggests otherwise, and Wiki is not known for being kind to climate skeptics.)

I followed up by mentioning what the New York Times recently reported: there were 1,200 coal plants being built or planned in Asia alone. Given this, was there a case for optimism in place of climate alarmism?

“Optimism has no place in science,” Dessler retorted. And personally, he claimed to be an optimist.

A Final Question

After the talk, I introduced myself, and Dessler politely remembered our lunch some years back in College Station. I pulled out my dog-eared copy of his Introduction to Modern Climate Change (2016 2nd edition, which I plan to review) and asked specifically if the fact of GHG forcing being logarithmic, not linear, was anywhere in the primer. (I could not find it and was perplexed!) He confirmed that it was not and needed to be–but that was a fact that even undergraduates knew….

I have a problem, a big one, with his answer. The log relationship (which Dessler covered in his Rice talk) is subtle and profound for the whole climate debate. It is a powerful argument against mitigation that grows stronger by the day. It says, essentially, that the more the atmosphere fills up with CO2, given its long life, the less effect that any reduction or addition has.

It points toward adaptation, not mitigation, as the future. Basic physics…..

With the boom of carbon-based energy in the US and globally, in fact, it is game-set-and-match Fossil Fuels given the logarithmic effect of GHG forcing.

Why did Dessler leave this out of his introductory textbook? Why are other important things missing, such as energy density, even the mere possibilities to explain the missing heat to explain the temperature “pause.” Yes, the direct effect of solar on recent global warming is modest, but what about the indirect effects hypothesized by Henrik Svensmark? Do we really know everything that is important to quantitatively define climate sensitivity?

I left the Rice University climate talk appreciative that Andrew Dessler was polite in person (he gets nasty toward skeptics in his tweets, the subject of a future post). But I was hardly dissuaded from my prior conclusion that this scientist is a deep ecologist who was far too confident and promoting half-truths for a cause. That he is not above ‘lawyering’ to present a black-and-white case for climate alarmism.


  1. John W. Garrett  

    Well done you!

    Congratulations for posing a critical question in public. Maybe some of those impressionable, indoctrinated, peer-pressured adolescents subjected to “Dessler-certainty” will commence to think for themselves.

    Anybody who has ever programmed a computer model knows full well that the output will reflect the programmer’s biases.


  2. Mark Bahner  

    “If we don’t take action, unchecked greenhouse-gas emissions would lead to global-average warming over this century of 5 degrees Fahrenheit to 9 degrees Fahrenheit…. This warming is as certain as death and taxes.”

    I ought to contact him and ask if he’ll give me 10,000-to-1 odds if I bet that warming over this century will be less than 5 degrees Fahrenheit. “Death” and “taxes” are certainly more certain than 10,000-to-1 (in fact, death is much more certain than 10 billion to one).

    My guess is that he wouldn’t be willing to put his money behind his claim.

    P.S. Whereas I already have put my money behind my global warming predictions:



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    […] the exaggerations of Professor Dessler, the certain climate alarmist, in critical posts, including here and […]


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