"Energy will hide out in the ocean for a while before it pops out into the atmosphere," Oppenheimer said.
For scientists studying the last 10 years, what's been happening "is a cool question," said U.S. National Oceanic and Atmospheric Administration scientist Gabriel Vecchi. But "anybody who tries to use the past 10 years to argue about the reality of global warming — which is based upon century-scale data — is just being distracting."
Jonathan Lynn, a spokesman for the IPCC, declined to comment on the content of the report because it hasn't been made final, but said it would provide "a comprehensive picture of all the science relevant to climate change."
The IPCC draft report says it is "extremely likely" that human influence caused more than half of the warming observed since the 1950s, an upgrade from "very likely" in the last IPCC report in 2007.
A final version will be presented at the end of the panel's meeting in Stockholm next week.
The IPCC's conclusions are important because they serve as the scientific basis for U.N. negotiations on curbing emissions of CO2 and other greenhouse gases. A global climate treaty is supposed to be adopted in 2015.