As of March 27, researchers had published 133 “consensus-skeptical” papers this year, bringing to 660 the number of such studies appearing since January 2014, blogger Kenneth Richard wrote on the skeptics website NoTricksZone.
 
“There has been quite an uptick in papers that question the consensus this year,” said Anthony Watts, who runs the influential WattsUpWithThat? website.
Studies published on his website and others include in the past few weeks include those that say:
• An exhaustive study published April 7 in Nature by University of Stockholm researchers examining hydrological patterns going back 1,200 years found that climate models cannot accurately predict extreme rainfall and drought.
• An article published April 4 in Nature Geoscience linked the melting of the Greenland ice sheets to hot spot activity within the Earth’s core, a finding that “must be included in studies of the future response to climate change,” said lead author Irina Rogozhina, a scientist at the Center for Marine Environmental Sciences at the University of Bremen in Germany.
• A March 21 paper by meteorologist Martin Hertzberg and chemist Hans Schreuder, evaluating figures behind the United Nations Intergovernmental Panel on Climate Change “consensus,” concluded that “nothing in the data supports the supposition that atmospheric CO2 is a driver of weather or climate.”
“As the body of evidence refuting climate alarmism continues to balloon, the question of how the IPCC can continue ignoring it becomes ever more glaring,” said engineer Pierre L. Gosselin, who runs the NoTricksZone website and translates climate news from German to English.
In spite of that research — or maybe because of it — Democrats have renewed their efforts to clamp down on climate dissent.
Two weeks ago, 17 attorneys general — 16 Democrats and Mr. Walker, an independent — announced that they would investigate and prosecute climate-related “fraud,” citing investigations by journalism outlets accusing Exxon Mobil Corp. of stifling its own scientific research in support of the “settled science.”
While Exxon Mobil has denounced the accusations as “preposterous,” Mr. Walker followed up Thursday with a subpoena calling for the Competitive Enterprise Institute’s work on climate and energy policy from 1997 to 2007, including the nonprofit’s “private donor information,” the institute said.
“We are committed to ensuring a fair and transparent market where consumers can make informed choices about what they buy and from whom,” Mr. Walker said in a statement. “If Exxon Mobil has tried to cloud their judgment, we are determined to hold the company accountable.”
The Competitive Enterprise Institute denounced the subpoena as “the latest effort in an intimidation campaign to criminalize speech and research on the climate debate, led by New York Attorney General Eric Schneiderman and former Vice President Al Gore.”
Mr. Watts called the Virgin Islands investigation “climate McCarthyism,” and even some nonskeptics weighed in on the institute’s behalf.
“No matter what you feel, the Competitive Enterprise Institute, a conservative libertarian think tank dedicated to free enterprise and limited government, is absolutely entitled to take the views that it does, to argue its views, and to be as wrong as it wants to be,” lawyer Scott H. Greenfield said on the Simple Justice blog.
Bloomberg View columnist Megan McArdle said in a Sunday op-ed that she supports “action on climate change,” but “that doesn’t mean I’m entitled to drive people who disagree with me from the public square.”
“Climate activists have an unfortunate tendency to try to do just that, trying to brand dissenters as the equivalent of Holocaust deniers,” she said.
Meanwhile, InsideClimate News, whose investigation last year into Exxon Mobil sparked the “AGs United for Clean Power” campaign, said the subpoena represents a “broadening of a multifaceted legal inquiry into whether fossil fuel companies broke any laws as they sought for decades to undermine the scientific consensus and head off forceful action to address the climate crisis.”
“For the first time, the investigation now appears to touch on the actions of third parties supported by the industry — and perhaps into their joint lobbying actions,” said the Friday report by InsideClimate News, which is funded by a host of liberal and pro-green foundations, including the Park Foundation.
Attorneys general in at least three states — California, Massachusetts and New York — are also reportedly looking into Exxon Mobil’s involvement in the climate change debate.
Attorney General Loretta Lynch told the Senate Judiciary Committee that her department has discussed pursuing civil charges against the “climate denial scheme,” as Sen. Sheldon Whitehouse, Rhode Island Democrat, put it.
“This matter has been discussed. We have received information about it and have referred it to the FBI to consider whether or not it meets the criteria for which we could take action on,” Ms. Lynch said at a March 9 hearing.
The problem with government probes into climate research is that they have been known to backfire.
In February 2015, Rep. Raul M. Grijalva, Arizona Democrat, came under intense criticism after launching an investigation into the funding sources of seven prominent university scientists who have challenged the consensus that climate change equals disaster.
The goal was to see if their research had been funded by fossil fuel companies, but Mr. Grijalva instead came under fire for conducting a “witch hunt.” The University of Delaware refused to provide the requested documents, and others denounced the probe as a threat to academic freedom.
Mr. Grijalva, the ranking Democrat on the House Natural Resources Committee, has yet to release the results of his investigation.