Deniers Have Launched a Losing Debate Over a 'Hiatus' in Global Warming

When a study last month found evidence of a slowdown in global warming, climate science skeptics gloated. Here's why they're wrong.
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A dog treads the frozen Arctic Ocean in Browerville, Alaska, June 6, 2006. (Photo: Justin Sullivan/Getty Images)

Research published in the journal Nature Climate Change rarely sparks celebration in the right-wing blogosphere. But that's how it went down last month, as climate change skeptics heralded a recent paper that "proves a 15-year hiatus in global warming" and rebuffs the "venomous charlatans" who peddled the climate change myth to a gullible public.

Alas, if only that were true.

Despite the self-congratulatory chorus on the right, the paper published last month actually found that global warming has continued over the last 15 years—just more slowly than in previous decades. And this finding is nothing new. For years now, reputable scientists have debated the exact rate of global warming since 2000, a micro-level disagreement that hinges on variables as esoteric as the historic reliability of thermometers.

Such details have never stopped ideologues from turning nuanced climate science into political theater, of course. In 2012, for example, Fox News grossly mischaracterized a British government report while declaring that global warming was "over," and, last year, Representative Lamar Smith began "investigating" the National Oceanic and Atmospheric Administration after the federal agency published evidence challenging the idea of a global warming slowdown.

The real lesson from the uproar isn't that climate change has stopped—it's that science is working.

The reality obscured by these anti-science shenanigans is that there is some legitimate debate surrounding climate change—or at least about how best to measure its progress. In 2015, the much-discussed NOAA study challenged earlier findings that said warming had slowed in the 21st century. The study did so in part by adjusting for "biases" in the historic data; it pointed out, for example, that the thermometers affixed to modern buoys have been shown to produce lower temperature readings than those carried by ships. When adjusting for this distortion and others, such as the relative shortage of data from the rapidly warming Arctic region, the researchers found no evidence that global warming had slowed since 2000.

For the most part, the new paper in Nature Climate Change doesn't quibble with NOAA's data adjustments, but it does reach a very different conclusion about the overall warming trend. Could this be a sign that NOAA's scientists were under the thumb of an authoritarian Obama administration bent on spreading the climate change hoax? Well, not exactly. The real explanation isn't quite as exciting.

According to John Fyfe, senior research scientist at the Canadian Centre for Climate Modeling and Analysis, and the paper's 11 co-authors, the NOAA study failed to find evidence of a slowdown primarily because its methods were to compare this century's warming data against a 50-year baseline, from 1950 to 1999. The problem, these researchers argue, is that a 50-year baseline includes the period from 1950 to 1970 when relatively lower greenhouse gas emissions and stronger mitigating factors (like emissions of sulfate aerosol, an industrial-era pollutant that actually lowers temperatures by reflecting sunlight) caused global temperatures to stall for two decades.

According to last month's paper, it makes more sense to compare recent warming trends with the 30-year period from 1972-2001, when temperatures rose more rapidly. Making this adjustment changes the baseline numbers and leads to the conclusion that global warming has indeed slowed down, at least temporarily.

Despite the noise on the Internet, of course, this finding does nothing to challenge the broader consensus that climate change is happening and that human activity is mostly to blame. (In fact, co-author Michael Mann is the same scientist whose controversial "hockey-stick" graph first ignited widespread public concern over global warming in the early 2000s.)

What this paper does offer is an incremental revision in how scientists might interpret current temperature data, with an eye toward improving their ability to accurately predict global warming trends in the future. Its main message—largely missing from news reports and blogs alike—is that carbon emissions interact with a wide range of other factors, from volcanic activity to El Niño weather patterns, in determining the trajectory of global temperatures.

All that is to say, the real lesson from last month's paper, as with the NOAA study before it, is that science is working, methodically grappling with the most complex problems of our time and inching closer to something we can understand as truth.

Or, if you prefer another interpretation, the takeaway is that global warming is finally finished!

I guess we can call it a toss-up.

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Catastrophic Consequences of Climate Change is Pacific Standard's year-long investigation into the devastating effects of climate change—and how scholars, legislators, and citizen-activists can help stave off its most dire consequences.

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