The New York financiers’ donations to climate misinformation think tanks are finally attracting the scrutiny long reserved for the Koch brothers and Exxon Mobil.

Robert Mercer and his daughter, Rebekah Mercer, are best known as the secretive billionaire megadonors who bankrolled and organized President Donald Trump’s campaign, poured at least $10 million into Breitbart News, and showered millions on a network of right-wing websites and think tanks. The family has spent $36.6 million on Republican races and super PACs since 2010.

The Mercers are less well known as patrons of the climate change denial movement, yet their spending has been equally generous and appears to be increasing, according to new, previously unreleased tax filings reviewed by HuffPost.

The Mercer Family Foundation in 2016 gave $800,000 to the Heartland Institute, a right-wing think tank and major proponent of climate change denialism, up from $100,000 the previous year. Heartland received about $5.2 million in average annual income between 2011 and 2015, meaning the Mercers’ donation could make up 15 percent of the organization’s funding in 2016.

The foundation gave $200,000 for a second year in a row to the Oregon Institute of Science and Medicine, a discredited medial research group best known for spreading a hoax petition in 2009 claiming that 30,000 climatologists rejected global warming. Based on the organization’s average income for the last few years, that donation could make up anywhere from one-third to 62 percent of its budget.

The Mercers made first-time donations to two other prominent groups last year: the CO2 Coalition, an organization born from the ashes of the defunct George C. Marshall Institute, which denied global warming and lobbied against the science behind acid rain and smoking-caused cancer, received $150,000; and the Arizona-based Center for the Study of Carbon Dioxide and Global Change, an oil-funded think tank run by former Peabody Energy executive Craig Idso, got $125,000.

In its first year, the CO2 Coalition raised $404,384, so the donation the Mercers disclosed for last year increased the budget by nearly 40 percent. For Idso’s outfit, which took in just $194,757, according to its most recent filing, the Mercer money would mark a 64 percent budgetary increase.

Tax disclosures typically become public a year after a nonprofit files, so the most recently available documents are from 2015. The Mercers’ contributions are detailed on the foundation’s most recent 990 tax form, which researchers at the nonpartisan Climate Investigations Center obtained and shared with HuffPost. Neither the Mercer Family Foundation, nor any of the four organizations, responded to a request for comment on Thursday afternoon.

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