A Reality Check on Clouds and Climate (N.Y. Times)

September 6, 2011, 5:44 PM

Dot Earth


I am often in awe of clouds, as was the case when I shot this video of a remarkable thunderhead somewhere over the Midwest. But I’m tired of the recent burst of over-interpretation of a couple of papers examining aspects of clouds in the context of a changing climate.

I’ve long pointed out that anyone trumpeting a conclusion about greenhouse-driven climate change on the basis of a single paper should be treated with skepticism or outright suspicion. I trust climate science as an enterprise because — despite its flaws — it is a self-correcting process in which trajectory matters far more than individual steps in the road.

There is always a temptation, particularly for those with an agenda and for media in search of the “front-page thought,” to overemphasize studies that fit some template, no matter how tentative, or flawed.

The flood of celebratory coverage that followed publication of a recent paper by Roy Spencer and Danny Braswell — proposing a big reduction in the sensitivity of the climate to greenhouse gases — was far more about pushing an agenda than providing guidance on the state of climate science. There’s a lot more on this below.

The same goes for the stampede on clouds and climate following publication of an important, but preliminary, laboratory finding from the European Organization for Nuclear Research (better known by its acronym, CERN) about how cosmic rays can stimulate the formation of atmospheric particles(an ingredient in cloud formation). It’s a long road from that conclusion to an argument that variations in cosmic rays can explain a meaningful portion of recent climate change.

There’s a long history of assertions that clouds can be a substantial driver of climate change, distinct from their clear potential to amplify or blunt(depending on the type of cloud) a change set in motion by some other force. But there’s still scant evidence to back up such assertions.

In weighing the new results on cosmic rays and the atmosphere, I find a lot of merit in Hank Campbell’s conclusion at Science 2.0:

[I]t isn’t evidence that the Sun’s magnetic field is controlling cosmic rays and therefore our temperature far more than mankind and pollution are doing.

It is simply science at work – finally, after a decade and a half of circling the wagons, hypotheses that were dismissed as conspiratorial nonsense by zealots get a chance to live or die by the scientific method and not by aggressive posturing.

new paper by Andrew Dessler of Texas A&M University bolsters the established view of clouds’ role as a feedback mechanism — but not driver — in climate dynamics through a decade of observation and analysis of El Nino and La Nina events (periodic warm and cool phases of the Pacific Ocean).

The paper directly challenges conclusions of Spencer and Braswell and anearlier paper positing a role of clouds in driving climate change.

Dessler, setting his findings and other work on clouds and climate in broader context, offered this observation this morning about the polarized, and distorted, public discourse:

To me, the real story here is that, every month, dozens if not hundreds of papers are published that are in agreement with the mainstream theory of climate science.

[ACR: I did a quick Google Scholar search for “CO2 climate change greenhouse” to put a rough upper bound on this and got ~9,000 papers so far in 2011.]

But, every year, one or two skeptical papers get published, and these are then trumpeted by sympathetic media outlets as if they’d discovered the wheel. It therefore appears to the general public that there’s a debate.

Here’s more from Dessler on his new paper:

A separate question has emerged around the Spencer-Braswell paper. Should it have been published in the first place?

As Retraction Watch (a fascinating and worthwhile blog) chronicled last week, the editor of Remote Sensing, the journal in which the paper appeared, emphatically — if after the fact — said no, emphasizing his view by very publicly resigning.

This move was hailed by defenders of the climate status quo in a piece run inThe Daily Climate and Climate Progress. Peter Gleick of the Pacific Institute, remarkably given space in Forbes, called the resignation “staggering news.”

But others, including the folks at Retraction Watch, wondered why the editor at Remote Sensing, Wolfgang Wagner, didn’t simply seek to have the paper retracted?

Roger A. Pielke, Jr., whose focus at the University of Colorado is climate in the context of political science, echoed that question, urging the new team at the journal to initiate retraction proceedings, adding:

If the charges of “error” and “false claims” are upheld the paper should certainly be retracted.  If the charges are not upheld then the authors have every right to have such a judgment announced publicly.

Absent such an adjudication we are left with climate science played out as political theater in the media and on blogs — with each side claiming the righteousness of their views, while everyone else just sees the peer review process in climate science getting another black eye.

Over the weekend, I asked Kerry Emanuel at the Massachusetts Institute of Technology for his thoughts both on the Spencer-Braswell paper and the histrionic resignation by the editor. Here’s Emanuel:

About the paper: I read it when it first came out, and thought that some of their findings were significant and important. Basically, it presented evidence that feedbacks inferred from short-period and/or local climate change observations might not be relevant to long-period global change. I suppose I thought that rather obvious, but not everyone agrees. The one statement in the paper, to the effect that climate models might be overestimating positive feedback, struck me as unsubstantiated, but the authors themselves phrased it as speculative.

But the interesting and unusual thing about this is that that what pundits said about the paper, and indeed what Spencer said about it in press releases, etc., in my view had very little to do with the paper itself. I have seldom seen such a degree of disconnect between the substance of a paper and what has been said about it.

Gavin Schmidt of Real Climate and NASA has posted a thorough and useful dissection of the situation, “Resignations, retractions and the process of science,” that comes to what I see as the right conclusion:

I think (rightly) that people feel that the best way to deal with these papers is within the literature itself, and in this case it is happening this week in GRL (Dessler, 2011) [the Dessler paper discussed above], and in Remote Sensing in a few months. That’s the way it should be, and neither resignations nor retractions are likely to become more dominant – despite the amount of popcorn being passed around.

There’s more useful context and analysis from Keith Kloor, who notes the role played by the Drudge Report in amping up the story (blogging at the Yale Forum on Climate Change and the Media), Mike LemonickJudith Curry and many others.

As always happens after such episodes, the one clear finding is that clouds remain a complicating component in efforts to project warming from the building greenhouse effect.

Joni Mitchell’s classic, with a bit of mangling, sums things up well:

They’ve looked at clouds from all sides now, as feedback and forcing, and still somehow, it’s clouds’ illusions most often recalled. More work is needed to know clouds at all.

8:52 p.m. | Postscript |
There’s more coverage of the Spencer-Braswell paper at Knight Science Journalism Tracker and the blogs of Roger Pielke, Sr. and William M. Briggs. Roy Spencer has posted a piece titled “More Thoughts on the War Being Waged Against Us.”