Physicist Richard Muller was skeptical of the whole climate change claim, but unlike most skeptics who are content to be just armchair critics, he did something about it.

In 2010, Muller and a team of scientists started the Berkeley Earth Surface Temperature (BEST), a project to rigorously review more than 39,000 temperature measurement stations across the globe (in a way that addressed the main criticism of climate sceptics, namely that the data are homogenized or adjusted. Muller's method, on the other hand, relies on raw data).

Last week, BEST released its latest paper concluding that not only is climate change real, it's also caused by humans. Muller wrote in The New York Times:

CALL me a converted skeptic. 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.

Climate change skeptics, however, remain unmoved.