ThinkProgress Editor in Chief Judd Legum sent an email to a billionaire donor bragging how the liberal blog’s environmental writer targeted a climate researcher who challenged a major Democratic talking point on global warming, according to leaked emails.

The blog’s environmental arm, ClimateProgress, took issue with pollster Nate Silver’s 538 website, hiring Dr. Roger Pielke, Jr. to write about global warming issues. Pielke is no skeptic of man-made warming, but he challenged a Democratic talking point that global warming was making extreme weather more severe.

ClimateProgress immediately embarked on a crusade to discredit him “[p]rior to Pielke writing anything” for 538 — based solely on the fact they didn’t like his research on extreme weather.

“Pielke basically has made a career of ‘accepting’ climate change but disputing that we can really do anything about it or that it has much of an impact,” Legum wrote in a July 2014 email to hedge fund billionaire Tom Steyer thanking him for his “support.”

Steyer is a major supporter of environmentalists and Democratic politicians. Steyer is a donor and bundler for the Clinton campaign, raising more than $100,000 for her campaign since 2015. He spent $73 million during the 2014 midterm elections.

ClimateProgress is part of the Center for American Progress Action Fund (CAPAF), which was created by Clinton’s presidential campaign chair John Podesta. Podesta also created the Center for American Progress, a liberal think tank, which gave CAPAF at least $1 million in 2015.

Legum’s email to Steyer was release by WikiLeaks from Podesta’s hacked Gmail account. It’s one of several emails involving the ThinkProgress blog.

ClimateProgress put out two articles attacking Pielke the same day he published a post on 538 headlined “Disasters Cost More Than Ever — But Not Because of Climate Change.” Pielke’s point was that extreme weather only does more damage today because there’s more wealth to destroy when hitting shore.

When economic growth is taken into account, “the overall trend in disaster costs proportional to GDP since 1990 has stayed fairly level,” Pielke wrote.

“Within hours, ClimateProgress published a comprehensive debunk, with quotes from many prominent climate scientists,” Legum wrote, chronicling Pielke’s eventual being forced to leave 538.

“Pielke was so upset with our piece, he called the scientists we quoted and threatened to sue them. Silver was forced to apologize,” Legum wrote. “Embarrassed, Silver was forced to publish a rebuttal to Pielke piece by an actual climate scientist, which was also devastating.”

Silver asked climate scientist Kerry Emanuel to rebut Pielke’s article. Emanuel wrote that he’s “not comfortable with Pielke’s assertion that climate change has played no role in the observed increase in damages from natural hazards.”

Silver never let Pielke publish any piece on global warming on 538 again — a fact Legum bragged to Steyer about in his email.

“I think it’s fair say that, without Climate Progress, Pielke would still be writing on climate change for 538,” Legum wrote.

“He would be providing important cover for climate deniers backed by Silver’s very respected brand,” he wrote. “But because of our work, he is not. I don’t think there is another site on the internet having this kind of impact on the climate debate.”

“Thanks for your support of this work. Looking forward to doing even more in the coming months,” Legum wrote to Steyer.

Update: Pielke told The Daily Caller News Foundation claims he threatened to sue his detractors was “a lie.” Reports that Pielke threatened legal action against two climate scientists came from The Huffington Post. Pielke says that’s false.

In fact, it was Legum who contacted 538 claiming Pielke had made legal threats against two scientists, according to HuffPo.

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