University of California at Berkeley professor Richard A. Muller long questioned the existence of global warming, but Muller say he is now a “converted skeptic.”
In a New York Times opinion article this weekend, Muller said his extensive research into climate change had caused him to reverse his opinion, and he says he now believe the earth is warming due to greenhouse gas emissions.
“Following an intensive research effort involving a dozen scientists, I concluded that global warming was real and that the prior estimates of the rate of warming were correct,” he wrote. “I’m not going a step further: Humans are almost entirely the cause.”
Muller had long stood as a skeptical voice against climate change, arguing that scientific holes in studies raised doubts about whether the earth was in fact warming as hundreds of other climatologists around the world had concluded.
Muller was heavily funded by the Charles Koch Charitable Foundation, run by petrochemical billionaire Charles Koch.
Tonya Mullins, a spokeswoman for the foundation, told the Los Angeles Times that the foundation’s support had no impact on Muller’s scientific conclusions. Mullins said the grants “strive to benefit society by promoting discovery and informing public policy.”
In Muller’s column, he wrote the average temperature on earth has risen by two and half degrees over the past 250 years, including a rise of one and half degrees over the past 50 years.
“It appears likely that essentially all of this increase results from the human emission of greenhouse gases.”
Michael Mann, the director of the Earth System Science Center at Pennsylvania State University, applauded Muller’s reversal on his Facebook page.
“I applaud Muller and his colleagues for acting as any good scientists would, following where their analyses led them, without regard for the possible political repercussions,” he wrote.
To read more about Muller’s reversal, you can read the Los Angeles Time’s story about it or you can read Muller’s New York Times Op-Ed.