A Brief Reminder that Models Aren't Always Right

Physicist and occasional Reason contributor Russell Seitz has an interesting letter to the editor on climate models in the current issue of Foreign Affairs. Seitz' letter reminds Foreign Affairs readers and editors that in recent decades they…

…have seen the nuclear winter melt down, the energy crisis metastasize into an oil glut, and the population bomb implode. This breathtaking string of global systems modeling fiascos leaves some analysts asking why climate models are deemed sacrosanct when variables as critical as the sensitivity of the climate to the doubling of carbon dioxide in the atmosphere have failed to converge on uncontroversial values.

Climate sensitivity refers to the equilibrium temperature increase expected to result from doubling the atmospheric levels of carbon dioxide. The United Nations' Intergovernmental Panel on Climate Change's (IPCC) fourth assessment report (4AR) finds that climate sensitivity is "likely to be in the range 2 to 4.5 degrees Celsius with a best estimate of 3 degrees, and is very unlikely to be less than 1.5 degrees. Values substantially higher than 4.5 degrees Celsius cannot be excluded."

What does Seitz mean by "fail to converage on uncontroversial values"? One example might be a recent talk in Washington, DC. by Massachusetts Institute of Technology climatologist Richard Lindzen who argued that new data suggests that climate sensitivity is around 0.5 degrees centigrade (see slides 18 through 22) which is far below the IPCC figures. 

See Seitz' Foreign Affairs letter here. In addition, you might want to take a look at Seitz' Reason article on the implications of carbon prohibition.