“Global warming is real.” This was Richard Muller’s conclusion in an op-ed for the Wall Street Journal last Friday. Muller, a long-time climate change skeptic and professor of physics at Berkeley, chaired a two-year study of surface temperatures called the Berkeley Earth Surface Temperature Project. He continued, “Perhaps our results will help cool this portion of the climate change debate.”

Of particular note was that the study was partially funded by organizations supported by the Koch brothers, prominent climate change deniers and contributors to conservative causes. It focused on what Muller perceived as flaws in the work of other climate scientists, such as Michael Mann, the much-maligned (by the right) Penn State scientist who was involved in the “ClimateGate” pseudo-scandal. Mann’s hacked emails had been held up by deniers as “proof” that climate scientists were manipulating data to hide past warming trends.

Of these other scientists’ work, Muller wrote: “Our results turned out to be close to those published by prior groups. We think that means that those groups had truly been very careful in their work… They managed to avoid bias in their data selection.”

Muller’s team analyzed virtually every surface temperature record available from monitoring stations around the globe. They found that most locations showed warming between 1 degree and 2 degrees Celsius since the 1950s—greater than the average of 0.64C that the Intergovernmental Panel on Climate Change found during its exhaustive study that was released in 2007.

Muller, who had a history of lambasting climate scientists and politicians who drew attention to the dangers of climate change, now says “you should not be a skeptic, at least not any longer.”

It should be noted that Muller spent more than half of his op-ed defending his prior skepticism—skepticism that persisted for years in the face of overwhelming scientific consensus on the reality of global warming—so he should not be too enthusiastically embraced for his sudden about-face. Furthermore, his study did not analyze the dangers of global warming or how much of it is due to human activity.

Indeed, it is likely that climate change deniers will alter their talking points to align with Muller’s study; there were legitimate reasons to be skeptical, they will say, and though they now believe global warming is real, they will continue to deny its dangers and that humans are fueling it.

Let’s hope that when they finally concede those points, it won’t be too late.