On Climate Studies, Meet the 'Worst-Worst-Case Scenario'

As the world puts to bed the hottest year on record, the Washington Post calls attention to a study suggesting we haven't seen anything yet. The paper by renowned climate scientist James Hansen—the New York Times notes that it was Hansen's testimony before Congress 35 years ago that helped put the topic on the nation's radar—warns that the pace of warming has already begun accelerating at a rate scientists have long warned about. Specifically, the study in Oxford Open Climate Change predicts that global warming is on track to spike 50% in the coming decades, with effects that could be catastrophic, per the Post. However, the above coverage, as well as a story in E&E News, make clear that other scientists disagree.

"That is very much on the high end of the range of estimates that are in the academic literature today," Zeke Hausfather of Berkeley Earth tells the Times. Michael Mann of the University of Pennsylvania wrote a detailed blog post in rebuttal to Hansen, asserting that "the claim that warming is somehow accelerating now is no more accurate than the false claim, advanced by climate change deniers at the time, that global warming had 'stopped' in the first decade of the 21st century." And Michael Oppenheimer of the Center for Policy Research on Energy and the Environment at Princeton sees Hansen's warning as useful mainly as a "worst-worst-case scenario," per E&E.

Hansen predicted as much: "I expect the response to be characterized by scientific reticence," he tells E&E. The former NASA scientist calls the much-touted goal of keeping warming under 1.5 degrees Celsius "deader than a doornail," per the Times. While many other scientists agree with that, Hansen differs in warning further that the world is poised to warm by 2 degrees Celsius by 2050. (He does offer more hope on this target, saying that a global push to reduce the use of fossil fuels could keep warming under 2 degrees.) The Times adds context, pointing out that the planet has warmed by 1.2 degrees Celsius so far and is already seeing worsening heat waves and storms. (Al Gore offers a more hopeful assessment of how humans can fix the problem.)