Richard Muller Converts, Human Activity Causes Global Warming
July 30, 2012

Richard Muller: Skeptical Scientist Converts, Says Climate Change Is Man-Made

Lee Rannals for - Your Universe Online

One skeptical climate scientist has changed his beliefs, and now says that human activity is indeed causing the Earth to warm.

Prof Richard Muller, who founded the Berkeley Earth Surface Temperature (BEST) project, admitted in a New York Times opinion piece on Saturday that he was a "converted skeptic."

He admitted that a new study aimed at looking into climate change skeptics' concerns helped alter his beliefs.

"Last year, 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," Muller wrote in the Times. "I'm now going a step further: Humans are almost entirely the cause."

He said he was concerned by claims that were made by climate researchers who had not been entirely open with their data.

Muller gathered up a team of 10 scientists, including Saul Perlmutter, winner of this year's Nobel Physics Prize for research showing the Universe's expansion is accelerating, to confront the skepticism.

"These findings are stronger than those of the Intergovernmental Panel on Climate Change [IPCC], the United Nations group that defines the scientific and diplomatic consensus on global warming," he wrote in the New York Times piece.

The team merged and collected 14.4 million land temperature observations from 44,455 sites across the world dating back to 1753. Previous research only went back to the mid-1800s and used a fifth as many weather station records.

They determined that over the past 250 years, records show that the Earth has risen by two and a half degrees Fahrenheit, including an increase of one and a half degrees over the most recent 50 years.

The temperature data from various sources was completely automated to help reduce human error during the research. The team concluded that despite their deeper analysis, their own findings closely matched the previous temperature reconstructions.

They analyzed the warming impact of solar activity, but found that over the past 250 years, the contribution of the sun has been "consistent with zero."

"Much to my surprise, by far the best match came to the record of atmospheric carbon dioxide, measured from atmospheric samples and air trapped in polar ice," Muller wrote in the Times. "While this doesn't prove that global warming is caused by human greenhouse gases, it is currently the best explanation we have found, and sets the bar for alternative explanations."

The BEST project has not yet been published in peer reviewed scientific journals, and one collaborator on the project declined to be named as an author of the research.

"Their latest paper on the 250-year record concludes that the best explanation for the observed warming is greenhouse gas emissions," Judith Curry of the Georgia Institute of Technology told BBC. "Their analysis is way oversimplistic and not at all convincing in my opinion."

"I don't think this question can be answered by the simple curve fitting used in this paper, and I don't see that their paper adds anything to our understanding of the causes of the recent warming," she told the Guardian.

Although Curry is not yet a converted skeptic, Michael Mann, director of the Earth Science System Center at Penn State University, says this research just confirms what everyone else has already believed. He faced criticism from climate skeptics for his famous "hockey stick" graph.

He told BBC that seeing a study funded by the Koch Brothers "demonstrate what scientists have known with some degree of confidence for nearly two decades: that the globe is indeed warming, and that this warming can only be explained by human-caused increases in greenhouse gas concentrations."