Models Predicted Too Much Warming, New Data Show

Published June 15, 2013

Climate models used by the United Nations Intergovernmental Panel on Climate Change and other climate groups to predict future temperatures have failed miserably at predicting climate in recent years, new data show.

Scientists overseeing temperature data collected by NASA satellite instruments compared real-world temperatures in the tropical troposphere since 1979 to 73 climate prediction models produced by international government agencies, universities, and other climate groups, including 19 models produced by U.S. agencies, universities, and climate groups. All 73 models predicted substantially more warming than actually occurred, with the mean of the 73 models predicting three times as much warming as actually occurred.

John Christy, the Distinguished Professor of Atmospheric Science and Director of the Earth System Science Center at the University of Alabama at Huntsville, provided the data. Christy’s colleague Roy Spencer published the data charts on his website.

“I continue to suspect that the main source of disagreement is that the models’ positive feedbacks are too strong … and possibly of even the wrong sign,” Spencer noted on his website

“The lack of a tropical upper tropospheric hotspot in the observations is the main reason for the disconnect in the above plots, and as I have been pointing out this is probably rooted in differences in water vapor feedback. The models exhibit strongly positive water vapor feedback, which ends up causing a strong upper tropospheric warming response (the “hot spot”), while the observation’s lack of a hot spot would be consistent with little water vapor feedback,” Spencer explained.

“The modelers and the IPCC have willingly ignored the evidence for low climate sensitivity for many years, despite the fact that some of us have shown that simply confusing cause and effect when examining cloud and temperature variations can totally mislead you on cloud feedbacks (e.g. Spencer & Braswell, 2010). The discrepancy between models and observations is not a new issue,… just one that is becoming more glaring over time,” Spencer observed.

James M. Taylor ([email protected]) is managing editor of Environment & Climate News.

Internet Info:

Roy Spencer, “Epic Fail: 73 Climate Models vs. Observations for Tropical Tropospheric Temperature,”