The WaPo editorializes:
Climate models have improved at matching the observed temperature record since the IPCC’s last report. The scientists admit that they still aren’t adept at modeling short time scales, such as 10 or 15 years, during which various factors can make average temperatures spike and dip. But climate change is a long-term effect, and the decades-long trend is what matters.
The authors did not shrink from addressing one of the primary threads that critics have been pulling in their effort to unravel the scientific consensus — the recent flattening of global temperature rise. “Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850,” the IPCC notes. Nevertheless, a detectable slowing of the warming trend between 1998 and 2012 might well have to do with recent volcanic eruptions, which add heat-reflective materials to the atmosphere, a decade-long solar cycle and simple decade-to-decade variability. The scientists also admit that some models might still overestimate the effects of certain human activities on the climate system.
There is a lot more work to do. Scientists still harbor considerable uncertainty about what will happen to low-level clouds in a warming world and about the effect of aerosols, many of which reduce warming but some of which promote it. Considerations like these lead to a wide estimated range for how sensitive the climate is to additional greenhouse gases.
The experts should keep working to refine their picture of the climate system, with the caution and skepticism that good science demands. Meanwhile, America’s leaders should not take the fruit of that skepticism — some continuing uncertainty — as license to continue stalling. Ignoring the real possibility of large increases in global temperature is not wise leadership. It’s wishful thinking.