Warming of the global mean surface temperature (GMST) occurs fastest when the Pacific Decadal Oscillation is in its warm phase (shown in red). The last cool phase of the Pacific cycle (shown in blue) coincided with a surface warming slowdown.
Graphic courtesy of the National Center for Atmospheric Research, NSF scientists found to describe the records.
“When I look at the new February 2016 temperatures, I feel like I’m looking at something out of a sci-fi movie,” Georgia Tech climate scientist Kim Cobb told AP science reporter Seth Boren- stein. “It is a portent of things to come.” Eventually, the ocean cycles will change phases again. At print time, for example, the El Niño appeared to be giving way to a La Niña. Then repeat, over and over — against a backdrop of acceler- ating warming caused by greenhouse gases.
Semantics of the “pause”
The cyclical nature of warming has been exploited by fossil fuel companies that fund work to downplay the problem of climate change. That has prompted some scientists to respond in ways that have been challenged by other scientists.
Several teams of scientists have published papers in recent years downplaying the statistical significance of the warming slowdown. “There is no disagreement that there is decadal variability, and that it is real and needs to be better understood,” said Thomas Karl, a NOAA scientist who led one of those teams.
Karl and other scientists have been derided by their own col- leagues for their findings (
j.mp/scientistfindings) (including in a February op-ed by leading climate scientists in Nature Climate Change) and attacked by politicians, who claim (without evidence) that their research was expedited to support climate rules by the Obama Administration.
The scholarly brouhaha boils down more to perspectives and semantics, however, than it does to meaningful differences in opin- ion regarding global warming. One of the papers singled out in the Nature Climate
Change op-ed was written by science historian and geoscientist Naomi Oreskes, experimental psychology professor Stephan Lewandowsky and climate scientist James Risbey. The paper was published by the Bulletin of the American Meteorological Society
last year. (
j.mp/amsabstract) Their paper was largely a call for scientists to use consistent and accurate language when describing the up-and-down warming trend — particularly to stop using the expression “warming pause.” Because there are “frequent fluctuations in the rate of warming around a longer-term warming trend,” it concluded that there was “no evidence” that the recent warming slowdown was unique. “‘Pause’ has a clear vernacular meaning,” Oreskes said. “Some climate skeptics and deniers have continued to repeat the claim that warming paused, to imply that scientists are wrong about global warming, and therefore we needn’t address it.” Because concentrations of atmospheric carbon dioxide con- tinue to rise quickly, global warming’s trajectory continues to be bent ever upward, despite the normal decadal oscillations that sci- entists are beginning to understand. There’s no guarantee we’ll see another period in which surface temperatures virtually stop rising. During future slowdowns, tem- peratures might just rise more slowly. Occasional spurts of warming will almost certainly continue to become more extreme.
Nations taking action, public increasing awareness
Last year was a notable one for the climate — in addition to the temperature record, the world agreed during United Nations ne- gotiations in Paris to attempt a new approach at slowing global warming.
Also in 2014, climate change became a divisive presidential campaign issue. Democrats championed climate rules published by President Barack Obama’s Environmental Protection Agency that underpin commitments the United States made in Paris. Republi- cans resisted, vowing to undo the EPA rules.
The Paris pact adopts a voluntary and cooperative approach to reducing climate pollution. Nobody yet knows whether it will suc- ceed, but analysis shows the climate actions pledged so far by in- dividual nations are insufficient to achieve the pact’s overarching
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