Prominent climate change sceptic admits he was wrong

The verdict is in: Global warming is real and greenhouse-gas emissions from human activity are the main cause.

This is according to Richard A Muller, professor of physics at the University of California, a MacArthur fellow, and co-founder of the Berkeley Earth Surface Temperature project.

The UN Intergovernmental Panel on Climate Change and hundreds of other climatologists around the world came to such conclusions years ago.

However, the difference now is the source: Muller is a long-standing and colourful critic of prevailing climate science, and the Berkeley project was heavily funded by the Charles Koch Charitable Foundation, which, along with its libertarian petrochemical billionaire founder Charles Koch, has a considerable history of backing groups that deny climate change.

In an opinion piece in the New York Times titled ‘The Conversion of a Climate-Change Sceptic’, Muller writes: “Three years ago I identified problems in previous climate studies that, in my mind, threw doubt on the very existence of global warming.

“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.

“I’m now going a step further: Humans are almost entirely the cause.”

The research has shown, Muller says, “that the average temperature of the Earth’s land has risen by 2 degrees Fahrenheit (1.1 degrees Celsius) over the past 250 years, including an increase of 1 degrees Fahrenheit over the most recent 50 years.

“Moreover, it appears likely that essentially all of this increase results from the human emission of greenhouse gases.”

He calls his stance “a total turnaround”.

Michael Mann, director of the Earth Science System Centre at Penn State University, said there was “a certain ironic satisfaction” in 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”.

Muller said he changed his opinion after reading the results obtained by re-examining more than 14m temperature records at thousands of sites around the world.