Climate change study forces sceptical scientists to change minds | Science | guardian.co.uk

Prof Richard Muller, a climate sceptic physicist who founded the Berkeley Earth Surface Temperature (Best) project, said he was "surprised" by the findings. "We were not expecting this, but as scientists, it is our duty to let the evidence change our minds." He added that he now considers himself a "converted sceptic" and that his views had received a "total turnaround" in a short space of time.
...It analysed the warming impact of solar activity – a popular theory among climate sceptics – but found that, over the past 250 years, the contribution of the sun is "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," said Muller....
Early indications suggest that climate sceptics are unlikely to fully accept Best's latest results. Prof Judith Curry, a climatologist at the Georgia Institute of Technology who runs a blog popular with climate sceptics and who is a consulting member of the Best team, told the Guardian that the method used to attribute human emissions to the warming was "way over simplistic and not at all convincing in my opinion".

Richard Muller: 'Humans Are Almost Entirely The Cause' Of Climate Change

"Humans are almost entirely the cause" of climate change, according to a scientist who once doubted that global warming even existed.

Mulling Over Muller | Power Line

But just how much of a “skeptic” was Muller? Here’s the opening from his 2008 interview with Grist.org:

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.

Müller lite: Why Every Scientist Needs a Classical Training « JoNova: Science, carbon, climate and tax

[Monkcton] In this reply to Dr. Müller’s much-touted editorials in the New York Times and the San Francisco Chronicle, I shall demonstrate by Classical methods that his principal conclusion “that global warming is real, that the prior estimates of the rate were correct, and that the cause is human” is incorrect a priori.