The founder and director of a climate change study project funded heavily by the Koch brothers, who last year reversed course and said he believed global warming was real, has gone one step further, writing in a weekend op-ed in the New York Times that he is now convinced the phenomenon is caused by humans.

In a piece titled, “The Conversion of a Climate-Change Skeptic,” Richard A. Muller, a University of California, Berkley physicist who founded the Berkley Earth Surface Temperature study (BEST) wrote that his, “total turnaround, in such a short time,” was driven by a new report from the group that concluded for the first time that global warming is a man-made problem. That revelation brings Muller essentially full circle from his stance a few years ago, when he criticized other global warming studies as flawed and questioned whether the Earth was even warming abnormally, dangerously fast at all.

ADVERTISEMENT

“Science is that narrow realm of knowledge that, in principle, is universally accepted,” Muller wrote. “I embarked on this analysis to answer questions that, to my mind, had not been answered. I hope that the Berkeley Earth analysis will help settle the scientific debate regarding global warming and its human causes.”

The BEST study, he wrote, found that the Earth had warmed by about two and a half degrees over the past 250 years, with the bulk of that spike occurring in the past 50 years. Moreover, he found that, “essentially all of this increase” was likely due to greenhouse gas emissions, a point climate change believers have accepted as fact for years.

To arrive at that conclusion, the group mapped the past two and a half centuries of global temperatures against various events, like solar flares and volcanic eruptions, and found that the temperature swings most closely corresponded to levels of atmospheric carbon dioxide whose historical levels could be measured in arctic ice. Further, they also examined possible methodological problems skeptics cite about past studies, such as questions about the scope and selectivity of data, ultimately determining that those questions did not impact their finding.

“These facts don’t prove causality and they shouldn’t end skepticism, but they raise the bar: to be considered seriously, an alternative explanation must match the data at least as well as carbon dioxide does,” Muller wrote.

Muller’s conversion is particularly notable because his research had been heavily bankrolled by the Koch’s, who have a well-documented history of financing climate change denial. A Greenpeace report earlier this year found that the Koch’s had given nearly $61.5 million since 1997 to groups denying climate change. The Charles G. Koch Charitable Foundation donated $150,000 to the BEST study, more than any other single organization.