Climate Predictions: Worst-Case May Be Most Accurate, Study Finds
New study looks to the clouds to solve a global warming mystery.
Atmospheric scientists John Fasullo and Kevin Trenberth studied global humidity patterns to get at an elusive question: When atmospheric carbon dioxide (CO2) levels double—as is expected by late this century—how much warmer will it become?
Estimates of this temperature increase, called equilibrium climate sensitivity, hover around 5 degrees F (2.8 degrees Celsius) by about 2100. But predictions vary more than twofold, from 3 to 8 degrees F (1.7 to 4.4 degrees Celsius).
The difference matters because higher temperatures mean larger problems with sea level rise and extreme weather, as well as large-scale changes in ocean circulation—which could in turn mean big changes on the ground.
With a 3 degree F increase, for example, New York City would