An interesting editorial in the New York Times by Richard Muller, a well-known former global warming skeptic, who even had his research partly funded by the Charles Koch Charitable Foundation (they are climate change skeptics).
He now says,
“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.”