The Berkeley Earth group has concluded that global warming is happening, according to the results of its study on temperature data released Thursday.
Over the course of about one year, the team, led by UC Berkeley physics professor Richard Muller and composed of climate experts, statisticians and physicists — including Nobel Prize-winning UC Berkeley professor Saul Perlmutter — compiled 1.6 billion temperature measurements and found “reliable evidence” of a rise in the average world land temperature of about one degree Celsius since the mid-1950s.
The study was tailored to address specific concerns raised by climate change skeptics, such as the urban heat island effect — the phenomenon in which the temperature of an urban area is significantly warmer than the rural areas surrounding it.
“There were huge uncertainties in the accuracy of the thermometers,” Muller said. “Many (stations) were close to buildings or other sources of heat that could greatly distort the picture.”
The study found the effect to be “locally large and real” but not significant enough to have a large impact on the rise in average land temperature because only a small percentage of the Earth’s land is urban.
Elizabeth Muller, project manager of the Berkeley Earth group and Richard Muller’s daughter, said contributions from the Charles G. Koch Charitable Foundation — Koch is the co-owner of Koch Industries, Inc., a conglomerate that operates oil refineries across the United States and Alaska — in no way affected how the research was conducted.
Elizabeth Muller said the purpose of the study was to look at what occurred from the 1950s to the present — not to predict the future.
Michael Mann, professor of meteorology at Pennsylvania State University, said the findings do not serve to further advance the study of global warning.
“Muller’s report simply verifies what scientists have already known, and this study did not further our scientific understanding of the problem,” he said.
The Berkeley Earth study comes at a time when public opinion on global warming has shifted. An October 2010 poll from the Pew Research Center found that 59 percent of Americans believed there is solid evidence that the earth is warming — down from 79 percent in 2006.
Fewer people believe global warming is an issue because environmental issues have been replaced by economic concerns, said William Patzert, a climatologist and oceanographer who has worked at the California Institute of Technology’s NASA Jet Propulsion Laboratory for more than 28 years.
With the study’s results verifying previous findings, Muller said it is time for politicians to move into a dialogue about how to reduce greenhouse gas emissions.
“Many of us believe we have to switch from our fossil fuel addiction to renewable energy sources, and green not only our homes but our country,” Patzert said. “If we do rid ourselves of fossil fuels and go to renewable energy, we might get hit in the head with a ping pong ball rather than a bowling ball.”
A previous version of this article incorrectly stated that Michael Mann said the group’s funding from the Charles G. Koch Charitable Foundation calls into question its objectivity. In fact, he did not.