The Global Warming Statistical Meltdown

Mounting evidence suggests that basic assumptions about climate change are mistaken: The numbers don’t add up.

From yesterday's WSJ. By Judith Curry. Ms. Curry, a professor and former chairwoman of the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology, is the president of Climate Forecast Applications Network.

Excerpts:

"A growing body of evidence suggests that the climate is less sensitive to increases in carbon-dioxide emissions than policy makers generally assume"

"The Earth’s surface temperatures have already warmed about 0.8 degrees Celsius since 1850-1900. This leaves 1.2 degrees Celsius (about 2.2 degrees Fahrenheit) to go."

"projections reflect the effects of rising emissions on temperatures simulated by climate models, which are being challenged by recent observations."

"the actual change in 70 years if carbon-dioxide concentrations double, called the transient climate response, is likely in the range of 1 to 2.5 degrees Celsius. Most climate models have transient climate response values exceeding 1.8 degrees Celsius. But the IPCC report notes the substantial discrepancy between recent observation-based estimates of climate sensitivity and estimates from climate models."

"the best estimate for transient climate response is 1.33 degrees Celsius with a likely range of 1.05-1.80 degrees Celsius."

"the long-term warming from a doubling of carbon-dioxide concentrations...are far lower than the average values of sensitivity determined from global climate models that are used for warming projections. Also our ranges are narrower, with far lower upper limits than reported by the IPCC’s latest report."

"Our paper is not an outlier. More than a dozen other observation-based studies have found climate sensitivity values lower than those determined using global climate models"

"the growing evidence that climate models are running “too hot.” Moreover, the estimates in these empirical studies are being borne out by the much-discussed “pause” or “hiatus” in global warming—the period since 1998 during which global average surface temperatures have not significantly increased."

"This pause in warming is at odds with the 2007 IPCC report,"

"The warming hiatus, combined with assessments that the climate-model sensitivities are too high, raises serious questions as to whether the climate-model projections of 21st-century temperatures are fit for making public-policy decisions."

"Continuing to rely on climate-model warming projections based on high, model-derived values of climate sensitivity skews the cost-benefit analyses and estimates of the social cost of carbon."