This Famous Climate Scientist Just Endured A Washington Inquisition

On Capitol Hill, climate scientist Michael Mann faced a panel of hostile lawmakers and witnesses at a wacky hearing devoted to questioning global warming.

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WASHINGTON — Climate science went on trial on Wednesday at a hearing held by Congress’s notoriously grouchy science committee.

“Much of climate science today appears to be based more on exaggerations, personal agendas, and questionable predictions,” said committee chair Rep. Lamar Smith of Texas. He has repeatedly questioned the basis of climate and environmental studies in his tenure, suggesting federal scientists had “put their thumb on the scale” of climate data in a 2015 study.

The “Climate Science: Assumptions, Policy Implications and the Scientific Method” hearing opened a day after President Donald Trump signed an executive order killing the Obama administration’s climate rules and guidelines. The order also demanded a review of the EPA’s Clean Power Plan to limit greenhouse gasses.

The witness list pitted Penn State climate scientist Michael Mann — a lightning rod for energy industry-funded attacks on scientists for two decades — against two scientists critical of their own field, former Georgia Tech scientist Judith Curry and University of Alabama satellite scientist John Christy, as well as a political scientist, Roger Pielke Jr. of the University Colorado, who has argued against links between climate change and extreme weather. These three climate skeptics had collectively testified 20 times previously at similar Congressional hearings.

The 2013 Intergovernmental Panel on Climate Change concluded that greenhouse emissions from burning fossil fuels were the “dominant cause” of the atmospheric warming seen in the last five decades. All of the witnesses agreed that greenhouses gases undoubtedly warm the atmosphere. They also agreed that carbon dioxide in the atmosphere is increasing the acidification of the oceans. But they didn’t agree on much else.

The hearing convened with a circus atmosphere, despite the seriousness of its title, with Curry telling readers of her blog to “get your popcorn ready,” ahead of time. At a recent energy industry-funded climate denier’s conference, Smith had said, “this hearing is going to be so much fun,” and promised to rein in “the so-called self-professed climate scientists.” Mann, for his part, beforehand retweeted about how much money Smith gets from the energy industry:

Rep. Lamar Smith gets most his campaign money from Oil & Gas industry. Can he be unbiased on climate science?…

"I will be there to attempt to inject some actual facts and some actual climate science,” Mann told BuzzFeed News, when asked why he was appearing as a witness. Mann has long been in this position at hearings, sometimes receiving death threats for it. Mann and Christy squared off at one in 2006, for example, over Mann’s climate “hockey stick” findings that atmospheric temperature increases were unprecedented compared to past centuries. That finding has been repeatedly validated since the hearing.

“If the world of climate science and politics was not a circus, this could in fact be a productive and interesting panel,” science policy expert Dan Sarewitz of Arizona State University told BuzzFeed News by email. “But I can’t imagine that actually happening.”

He was right.

Charges of “bullying,” name-calling, and Stalinism by and against climate scientists was perhaps the largest area of discussion at the hearing. Pielke was criticized for sending unfriendly emails to Mann. Mann, meanwhile, was criticized for calling Curry a “climate change denier,” which he denied. But he did call her a "climate science denier" in his written testimony, he acknowledged, over her agreement with EPA chief Scott Pruitt's dismissal of carbon dioxide's role in climate change and similar moves.

“Calling someone a denier is a Stalinist tactic,” said Rep. Dana Rohrabacher of California at one point in the hearing.

Mann had questioned Smith’s motives earlier in the hearing, attracting Rohrabacher’s ire, by noting his appearance at the Heartland Institute conference, and clashing with the committee chair (quite a rare thing from a Congressional hearing witness) over whether the conference filled with individuals who deny climate change is real was a “climate denier” conference or not.

Also much discussed was whether Curry, Christy, and Pielke are “fringe” scientists in their views of climate science. There were duelling disagreements between Democratic (for) and Republican (against) representatives over whether 97% of climate scientists agree that temperature records show climate change is mostly a man-made phenomenon, which both Christy and Curry questioned.

“I’ve been called a denier,” Curry said. “That’s not the behaviour of a scientifically respectful discussion.”

As the sole establishment scientist at the witness table, a pugnacious Mann took many shots as well, criticized at one point for a defamation case he has, so far, successfully waged against a conservative news outlet. Pielke called him “the leader of the US climate movement,” which seemed to surprise everyone.

The cavalcade of hurt feelings was a common theme from the witnesses and the elected officials at the hearing, almost enough to obscure the moments of scientific agreement and disagreement. Rep. Don Beyer of Virginia, a Democrat, decried a “food fight among scientists” at the hearing.

In scientific terms, the hearing resolved into a debate between Curry and Christy, who argue that climate science is inadequate to explain the atmospheric warming seen in the last century, about 1 degree Fahrenheit.

“There’s a lot of natural variability,” Curry said, particularly in ocean warming, that needs to be explained before climate predictions could be made. Mann and Christy duelled over satellite temperature measurements of the upper atmosphere, with Mann arguing that there is a 1 in 10,000 chance, statistically, that the observations of warming in the last century were a fluke. Mann and Pielke, meanwhile, disagreed on whether climate change causes extreme weather events. (Many mainstream scientists also disagree on this point.)

Congressional representatives at times confused all the witnesses with their questions, variously asking for explanations of what causes ice ages, why sulfuric acid was cut from industrial smokestacks in the 1970s and why it might snow more in Antarctica.

The only recommendation from the panel on what to do about climate change came from Pielke, who advocated a tax of a few pennies on each gallon of gas to fund technologies to deal with the problem. Republicans joked this was “blasphemy.”

But one final area of agreement emerged among the panel witnesses toward the end of the hearing — that investing in satellites to watch the climate was valuable, whether to prove or disprove the science. As Rep. Elizabeth Esty of Connecticut noted, big cuts to those satellites are in the 2018 federal budget the Trump administration proposed earlier this month.

“We do have to act if the risk is sufficiently great,” she said.

Dan Vergano is a science reporter for BuzzFeed News and is based in Washington, DC.

Contact Dan Vergano at

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