“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.”
“My total turnaround, in such a short time, is the result of careful and objective analysis by the Berkeley Earth Surface Temperature project . . . Our results show that the average temperature of the earth’s land has risen by two and a half degrees Fahrenheit over the past 250 years, including an increase of one and a half degrees over the most recent 50 years. Moreover, it appears likely that essentially all of this increase results from the human emission of greenhouse gases.”
Both the strength and weakness of Muller’s analysis are that it relies on statistical analysis of weather, solar, and emissions trends. He views this as a strength because it avoids reliance on complex climate models. But it’s also weakness because the models, unlike his analysis, are based on the physical processes involved in climate rather than simply looking at the earth’s climate as a black box with certain inputs and outputs. In any event, he deserves praise for being willing to investigate the facts and then admit publicly that he has changed his mind. That’s all too rare these days.
As Muller says, the next step is “agreeing across the political and diplomatic spectrum about what can and should be done.” Among those who accept the reality of climate change, there are certainly strenuous disagreements about strategy. But if everyone would at least admit the problem is real, that would be a step forward in our public discourse.