Why Hasn't Earth Warmed as Much as Expected?

Planet Earth has warmed much less than expected during the industrial era based on current best estimates of Earth’s “climate sensitivity” — the amount of global temperature increase expected in response to a given rise in atmospheric concentrations of carbon dioxide (CO2). In a study to be published in the Journal of Climate, a publication of the American Meteorological Society, Stephen Schwartz, of Brookhaven National Laboratory, and colleagues examine the reasons for this discrepancy.

According to current best estimates of climate sensitivity, the amount of CO2 and other heat-trapping gases added to Earth’s atmosphere since humanity began burning fossil fuels on a significant scale during the industrial period would be expected to result in a mean global temperature rise of 3.8