The mainstream media is celebrating a physicist who allegedly did a U-turn on his global warming views and now says humans are the cause.

Except Richard Muller had already said in 2008 that man was a cause of global warming.

Nonetheless, the San Francisco Chronicle, for example, reported July 31: “The hot issue of global warming got hotter Monday when a UC Berkeley physicist, once a loud skeptic of human-caused climate change, agreed not only that the Earth is heating up, but also that people are the cause of it all.”

Never mind that in an interview almost four years ago with the environmental magazine Grist, Muller said man was a cause of global warming.

Grist: What should a President McCain or Obama know about global warming?

Muller: The bottom line is that there is a consensus — the [Intergovernmental Panel on Climate Change] — and the president needs to know what the IPCC says. Second, they say that most of the warming of the last 50 years is probably due to humans. You need to know that this is from carbon dioxide, and you need to understand which technologies can reduce this and which can’t. Roughly 1 degree Fahrenheit of global warming has taken place; we’re responsible for one quarter of it. If we cut back so we don’t cause any more, global warming will be delayed by three years and keep on going up. And now the developing world is producing most of the carbon dioxide.

Even Muller appears to have forgotten what he said in 2008.

In his July 28 New York Times op-ed, Muller says he came to this conclusion in 2011. “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.”

Muller didn’t respond to a question in an email about the discrepancy concerning when he came to believe in human-induced global warming, but responded to another question about his credentials.

Muller co-founded Berkeley Earth Surface Temperature (BEST), which released a study this month. Muller is not a climatologist. Many who support global warming have attacked the credentials of critics who were not climatologists. For example, in 2009, Bill Chameides, the dean of Duke’s Nicholas School of the Environment, wrote an op-ed for The Huffington Post saying those who doubted global warming were “non-experts” because they were not climatologists.

Chameides wrote: “Have you noticed that a new kind of scientific expert has been born? It is the non-climate scientist ‘climate scientist,’ better known in the trade as the NCSCS. ... What is a[n] NCSCS? It is someone who is not a climate scientist but is nevertheless happy to speak authoritatively about the alleged scientific errors being made by the real climate scientists. A dead ringer for a[n] NCSCS is one who begins with words to the effect of: ‘I am not a climatologist, but. ...’ ”

Chameides didn’t respond to an email asking how Muller’s testimony should be viewed since Muller is not a climatologist.

Muller defended his credentials when asked about not being a climatologist: “I don't know what the definition is. It is unfortunate that this field seems to emphasize credentials rather than science.” Muller also forwarded citations of his published works on climate that “have appeared in some of the most prestigious peer-reviewed journals.”

John Christy, a climatologist and a professor at The University of Alabama-Huntsville, said Muller has been on record in the past “promoting human-induced global warming.”

“I sat next to Muller at a (U.S.) House hearing last year,” Christy said in an email. “Nothing he said gave me the feeling he was a ‘skeptic.’ I also find his result that greenhouse emissions, to him, are the only thing that can cause slow warming in global temperature when such changes have occurred down through the centuries, i.e. before the BEST record begins. Climate variations have been around long before the mere 250 years of the BEST dataset.”