"The melting of continental ice sheets is expected to have an effect on the climate in this century," he said.
Factoring in slow feedbacks from ice and vegetation changes would generate a significantly higher ECS, likely in the 4 to 6 C (7.2 to 10.8 F) range, the paper notes. The range would be pushed even higher if climate-greenhouse gas feedbacks from land and ocean carbon sinks were also included.
Of course, these higher values would have to be set in the context of a longer time scale, meaning their full effects wouldn't be felt for thousands of years.
A more immediately useful metric included in the IPCC report is probably the transient climate response, which describes the response of climate systems to gradual increases in carbon dioxide and can be applied to a particular moment or period of time.
Ultimately, said Gavin, the ECS is best thought of as a mental exercise -- a way of estimating a range of outcomes without predicting them directly.
"It's like a measure of IQ, only applied to models," he said. "Knowing the IQ of a model isn't going to predict how it'll do on a test, or whether or not it'd flunk a job interview. But it still has a connection."
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500