Pennsylvania State University climatologist Richard B. Alley, whom Gillis quoted in his article, seems to have the prompted the post. In his article, Gillis presented “one of the canonical projections of climate science”—that the average surface temperature of the earth is likely to increase by five or six degrees Fahrenheit, with a doubling of carbon dioxide in the atmosphere—and contrasted that with a prediction from skeptics, who say that the increase is likely to be less than two degrees. Apparently, Alley got in touch with Gillis to say:
[He] gets annoyed by the way this contrast is often presented in news accounts. The higher estimate is often put forward as a worst case, he pointed out, while the skeptic number is presented as the best case.
In fact, as Dr. Alley reminds anyone who will listen, and as he recently told a Congressional committee, the estimate of 5 or 6 degrees is actually mildly optimistic. Computer programs used to forecast future climate show it as the most likely outcome from a doubling of carbon dioxide, but those programs also show substantial probabilities that the warming will be much greater.
The true worst case from doubled carbon dioxide is closer to 18 or 20 degrees of warming, Dr. Alley said — an addition of heat so radical that it would render the planet unrecognizable to its present-day inhabitants.
Gillis then goes on to give a brief description of some of the challenges of accurately determining “climate sensitivity,” explaining that “scientists are simultaneously trying to project the earth’s response to a given future level of carbon dioxide, and to project how high the carbon dioxide will actually go before emissions are brought under control.”
Gillis’s front-pager was the second installment in a new climate series, “Temperature Rising,” that the Times launched on November 13. As the paper’s environment editor, Erica Goode, recently explained to CJR, the series will “focus on the central arguments in the climate debate and examine the evidence for global warming and its consequences.”
[Update, 1/4: In an e-mail responding to questions about the usefulness of this sort of back-to-basics journalism, Yulsman said he has been struck by the disconnect between scientists’ concern about climate change and the public’s general apathy.
“Can explanatory science journalism targeted at non-experts help?” he wrote. “I doubt it’s going to elevate the issue on the list of public priorities. But my hope is that the Climate Central piece that I wrote, and the more extensive, narrative-driven, and more broadly distributed CO2 story by Justin Gillis, are now out there, waiting to be picked up by people who are confused but curious as authoritative sources of information when the climate change wars heat up again. In the age of Web 2.0, when there is so much conflicting information floating around out there, much of it completely without merit, my hope is that good, old fashioned journalistic verification can win out, one small post at a time, little by little by little.”]
Taken together, Gillis and Yulsman’s articles, plus the follow-up post from Gillis, are an exemplary contribution to what will hopefully be an even wider effort to revisit some of the basic scientific context undergirding the ongoing efforts to curb planet-warming greenhouse gas emissions.