A Free-Market Energy Blog

The Climate Science Debate Is Joined! Hallelujah!

By Robert Bradley Jr. -- December 4, 2017

“… we don’t have a first-principles theory that tells us what we have to get right in order to have an accurate projection [of anthropogenic climate change]…. This is sort of an emergent knowledge base. So, that’s the translation of this last statement, ‘To date, a set of diagnostics and performance metrics that can strongly reduce uncertainties in global climate sensitivity,’ a la projections, ‘has yet to be identified’.” (p. 89)

“… if the [temperature] hiatus is still going on as of the sixth IPCC report, that report is going to have a large burden on its shoulders walking in the door, because recent literature has shown that the chances of having a hiatus 18 of 20 years are vanishingly small.” (p. 92)

– William Collins, Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory. Quoted in “Climate Change Statement Review Workshop,” American Physical Society. January 8, 2017 Transcript.

I just got the news from John Droz:

Since it didn’t get a lot of press, not many people know that there was a very high-level Climate Change debate. This was sponsored by APS (a physics society). The professionally moderated meeting consisted of three top experts on each side of the global warming issue. It was a lively discussion.

Yes, there was a rigorous exchange of expert thinking, and yes, THE SCIENCE IS NOT SETTLED. What is settled is unsettled science. And the evidence continues to mount toward lower sensitivity climate estimates, as in global lukewarming.

Below, I excerpt from one of the opening presentations by William Collins, Director of the Climate and Ecosystem Sciences Division, Earth and Environmental Sciences Area (EESA), Lawrence Berkeley National Laboratory. He was a lead author of chapter 9 in the Fifth Assessment (latest) IPCC report, Climate Change 2013: The Physical Science Basis.

Collins is hardly a ‘skeptic’ but a mainstream fellow–who in the presence of esteemed experts is telling a story that hitherto has been muffled by the activists. With climate intellectualism thawing, expect a lot more truth telling in the next weeks, months, years.

This is but one excerpt of a much longer presentation and discussion, which has been summarized here.

The debate is joined!


One MetroTech Center
10 19th Floor
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DR. FRANCIS SLAKEY, Associate Director of Public Affairs; JEANETTE RUSSO, Office Manager and POPA Studies Administration Specialist


DR. ROBERT JAFFE, Chair; DR. MALCOLM BEASLEY, APS President; DR. KATE KIRBY, Executive Officer




DR. MICHAEL HOLLAND, Chief of Staff; DR. ARI PATRINOS, Deputy Director for Research




DR. COLLINS: I am Bill Collins. I head the weather science department at Berkeley. I also teach earth and air science at Berkeley. And I guess my role here today is as one of the lead authors of chapter 9 in the fifth IPCC report.

p. 87–88

“There are few instances of diagnostics where larger intermodel variations in the past are well-correlated with comparably large intermodel variations in the model projections.” It actually turns out to be very hard to use past as prologue….  Finally, and this is perhaps the core thing for a group like this, we don’t have a first-principles theory that tells us what we have to get right in order to have an accurate projection.

So, let’s just make sure that that’s clear. We do not have a first-principles theory for that. This is sort of an emergent knowledge base.  So, that’s the translation of this last statement, “To date, a set of diagnostics and performance metrics that can strongly reduce uncertainties in global climate sensitivity,” a la projections, “has yet to be identified.”

pp. 40–43

You say, “Models cannot reproduce the observed global mean surface temperature even with the observed radiative forcing.” The reason I went through this whole exercise on forcing is that it is not observed. It is calculated. And the aerosol competent [Sic. Presumably “component”] of that is highly uncertain.

The models we use for the greenhouse gases, those are really good, but the aerosol component is uncertain. Dealing with uncertainty in chemistry, the microphysics of the aerosol is a mess. It’s basically the physics [of] dirt, quite literally. So, it’s messy.

And each model is computing its own radiative forcing. We do not prescribe that information. We hand them concentrations. They are asked to compute forcing there that [Sic.].

And even under controlled circumstances, we can show that something like maybe a quarter, in fact, about a quarter of the response variation we see in the ensemble is just due to uncertainties in the forcing.

Even though we try to control for that, even though we claim we are handing them exactly the same climate conditions, we are handing them chemical boundary conditions and not radiative forcing boundary conditions to compute from that the radiative forcing.

And that’s about a quarter of the variation we see in response across the model ensemble. Major uncertainties associated with black carbon and particularly with cloud-radiative interactions for reasons I will be happy to come back to. It’s called the Twomey effect.

So, one of the issues that you raised because of the tininess of this perturbation of the boundary conditions is [see slide, p. 44], how can you be sure, given the fact that uncertainties and fluxes in the climate system are quite large and these perturbations and boundary conditions are small, how can you be sure that, when you look at a field like temperature which has a lot of stuff, a lot of different processes that contribute to its variations, how can you be sure that you are correctly interpreting the influences?

This is also a drawing on work that Ben [Santer] and his colleagues pioneered. But you can use gradients in the temperatures as a clue and a means to get through that thicket of different influences on the temperature.

And one of the most powerful tools — and a number of people in this room have contributed to this literature John [Christy], Ben [Santer], others — has to do with the vertical gradients in temperature in the earth’s atmosphere.

pp. 90–92

I think you accurately captured the state of the field currently. We are unsure about what — we know that there are several possible causes [of the warming hiatus]. And they are stated in the report. And also, you capture them correctly as well.

They could be errors in the forcing. It could being [Sic.] a mode of natural variability that the models are not correctly reproducing. And it could be cases or it could be that the models are overly sensitive. And so, all three are noted in that the IPCC report and will be actively investigated.

I do not have an opinion. We thought while we were writing this report that it was aerosols. And there were a number of — people became very alarmed. There were four meetings that went into this report, four face-to-face meetings.

… we were having these frantic meetings between people like myself on radiative forcing and the later chapters that were looking at these projections saying oh, my God. The models are running hot. Why are they running hot? By “running hot,” I mean running hot for 2011, 2012 as we were writing the report.

So, there was a lot of speculation that the projections had sort of overcooked the level of air pollution controls that were going to cause aerosol loading to decrease in the near future. That is a plausible explanation.

Other people have looked at subtle amounts of volcanic activity that have since gone undetected. This is work by Susan Solomon, other changes in the stratosphere. This is one of those topics that I think is going to have to be sorted out.

Now, I am hedging a bet because, to be honest with you, if the hiatus is still going on as of the sixth IPCC report, that report is going to have a large burden on its shoulders walking in the door, because recent literature has shown that the chances of having a hiatus of 20 years are vanishingly small.

pp. 93–95

The first calculations of greenhouse gas warming done by Arrhenius were done using the tools of the trade circa 1880. And he got most of the facts right because he knew, obviously, how to alter the greenhouse effect of the climate system and could write down essentially a zero-dimensional model of the climate system which reproduces a lot of the qualitative behavior we see here.

So yes, we are asking the climate models to do things that — we are no longer looking at this as a point problem, which is the way Arrhenius looked at it. We are looking at the model in detail as we have in the past.

But I think to come away with the fact this whole thing is highly uncertain, we fail to recognize both the insight that Arrhenius had, which I think still holds true today, and the fact that the climate models, despite the fact that they have those uncertainties, have on a number of cases predicted behavior that was subsequently verified, which is certainly a nice thing to see in cosmology. And it’s very nice to see in the climate.

There is actually a beautiful book written by Ray Pierrehumbert called “The Warming Papers.” I strongly urge you to look at that book because it deal with — there are a number of cases where the climate models anticipated behavior the observing systems at the time could not see and they subsequently saw. And these include changes of large scale beyond the earth’s atmosphere due, we think, to the influence of energy.


Richard Lindzen then questions a key variable with uncertain magnitude and even sign, aerosol forcing, with Steven Koonin and William Collins (pp. 95-96)

LINDZEN: I think there are certain things here that are a little bit peculiar, the business of the fingerprint. The only thing you are saying is when you are nearly transparent to space, you are going to have cooling to space. And when you get further in, you are deep and then you will get warming, but that depends on the feedback. And there is no signature that will distinguish different 24 sensitivities in that. So, it’s a little bit awkward.

KOONIN: We are going to get onto that, I suspect.

LINDZEN: Also, black carbon isn’t the only reason you can get the sign wrong.


LINDZEN: Aerosols can, for instance, cause condensation of ice and change the character.

KOONIN: That was the indirect aerosol?

COLLINS: Yes, Dick is exactly right. There are a number of reasons why the science can change.


This is just a taste of what many scientists and non-scientists alike will be discussing and debating in the weeks and months ahead.

And it could be a preview of a highly publicized “red team/blue team” physical science debate as teed up by Steven Koonin and proposed by EPA Secretary Scott Pruitt.

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