Future climate warming “relatively severe"—or “vastly worse than previously thought”?
DOI: 10.1063/PT.5.8024
Current news coverage of a high-visibility scientific paper illustrates the difficulties of presenting climate research to the media. How far should scientists and science-information officials go in translating measured, reserved scientific information into meaningful, constructive public information?
In the 2 January Nature, researchers report evidence justifying an expectation of “relatively severe” future global warming. On “the basis of the available data,” they carefully stipulate, “the new understanding presented here pushes the likely long-term global warming towards the upper end of model ranges.” Taking “the available observations at face value,” they write, “implies a most likely climate sensitivity of about 4 °C, with a lower limit of about 3 °C.”
Expert observers, also emphasizing caveats, have pronounced the evidence compelling. Writing at the blog RealClimate, climatologists Michael Mann and Gavin Schmidt end with this: “If the climate indeed turns out to have the higher-end climate sensitivity suggested . . . here, the impacts of unmitigated climate change are likely to be considerably greater than suggested by current best estimates.”
In a Nature News and Views commentary complementing and explaining the scientific paper, Hideo Shiogama and Tomoo Ogura of Japan’s National Institute for Environmental Studies also present a carefully qualified view. Their essay’s summarizing subhead, calling the paper an “evaluation of atmospheric convective mixing and low-level clouds in climate models,” says that it “suggests that Earth’s climate will warm more than was thought in response to increasing levels of carbon dioxide.” The commentary ends by describing the effort needed “to solve the recondite climate-sensitivity puzzle"—that is, to answer the monumentally complex question of how hot the climate will get from human influences.
Contrast that cautiousness with this headline on a “public release” from EurekAlert!, the news service operated by the American Association for the Advancement of Science: “Cloud mystery solved: Global temperatures to rise at least 4 °C by 2100; Cloud impact on climate sensitivity unveiled.”
EurekAlert!'s opening sentence, repeated at the Times of India , declares “Global average temperatures will rise at least 4 °C by 2100,” then adds: “and potentially more than 8 °C by 2200 if carbon dioxide emissions are not reduced, according to new research published in Nature.” But the Nature paper itself contains no statement resembling those added words. EurekAlert! links its public release to a media and communications manager associated with the University of New South Wales, home institution of the paper’s lead author.
Slate‘s headline proclaims “Climate change vastly worse than previously thought.” National Geographic‘s article opens effusively:
“This degree of warming would make large swaths of the tropics uninhabitable by humans and cause most forests at low and middle latitudes to change to something else,” says Steven Sherwood of Australia’s University of New South Wales, who led the study.
The changes, Sherwood says, would take Earth “back to the climate of the dinosaurs or worse, and in a geologically minuscule period of time—less than the lifetime of a single tree.”
A Sydney Morning Herald article ‘s opening contains this line: “The research . . . says a 4-degree rise in temperature would be potentially catastrophic for agriculture in warm regions of the world, including Australia.” In fact, whether or not the research has been so interpreted, the Nature paper itself says no such thing.
The Huffington Post‘s headline announces, “Climate change worse than we thought, likely to be ‘catastrophic rather than simply dangerous.’”
Catastrophic? Nothing like that volatile word appears in the Nature paper. But the Huffington Post piece relies on an article in the Guardian, which in turn relies heavily on comments quoted from lead researcher Sherwood. One quotation does include the word:
“4 °C would likely be catastrophic rather than simply dangerous,” Sherwood told the Guardian. “For example, it would make life difficult, if not impossible, in much of the tropics, and would guarantee the eventual melting of the Greenland ice sheet and some of the Antarctic ice sheet,” with sea levels rising by many meters as a result.
That Guardian piece concludes with this:
Sherwood accepts his team’s work on the role of clouds cannot definitively rule out that future temperature rises will lie at the lower end of projections. “But,” he said, for that to be the case, “one would need to invoke some new dimension to the problem involving a major missing ingredient for which we currently have no evidence. Such a thing is not out of the question but requires a lot of faith.”
He added: “Rises in global average temperatures of [at least 4 °C by 2100] will have profound impacts on the world and the economies of many countries if we don’t urgently start to curb our emissions.”
(The bracketed insertion appears in the article.)
It’s no surprise that the overall context Sherwood intends for his public comments is not just technical, but technopolitical. The opening sentences in Nature‘s explanatory News and Views commentary acknowledge as much for the paper’s wider implications:
Earth is warming because of increased atmospheric concentrations of greenhouse gases, including carbon dioxide, caused by human activities. To develop policies that can help to control anthropogenic interference in climate, estimates of climate sensitivity—the mean global temperature response to a doubling of CO2 levels—are required, and have been sought for decades.
Although all of the news coverage involves the technopolitical dimension, some of it has stayed close to what’s reported in the paper by Sherwood and colleagues—for example, another Guardian piece and a report at Ars Technica. An article at Science—representing, as EurekAlert! does, the American Association for the Advancement of Science—ends by mentioning not 4 °C but 3 °C. It quotes Schmidt: “This new study is just one bit of information, but I believe it pushes the likely climate sensitivity closer to where it’s always been, up around 3 °C.”
At the Washington Post, the editorial “Climate-change response demands urgency” summed up this way: The “results offer one more argument against assuming a relatively benign climate future. That doesn’t mean the future can be forecast, even now, with certainty. It does mean that to take no action, on the hope that nothing too bad is in store, is to place a foolish bet with humanity’s future.”
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Steven T. Corneliussen, a media analyst for the American Institute of Physics, monitors three national newspapers, the weeklies Nature and Science, and occasionally other publications. He has published op-eds in the Washington Post and other newspapers, has written for NASA’s history program, and is a science writer at a particle-accelerator laboratory.