It warns that, by 2100, the planet’s natural system could change so dramatically that enormous “superstorms,” sometimes powerful enough to hurl ocean boulders hundreds of feet into the air, will form in the Atlantic Ocean. Seas could also rise so quickly that they will inundate coastal cities—including New York, Washington, and San Francisco—rendering them unlivable before the end of the century.
Hansen’s paper isn’t the first to spell out a scenario for climate doom. What makes it so harrowing, though, is that it says all these consequences would follow the global average temperature rising a relatively small amount: only two degrees Celsius. That isn’t an arbitrary target. The nations of the world have repeatedly agreed to keep climate change specifically below two degrees Celsius, but, without as yet uninvented technology, it will be scientifically unlikely.
If these terrifying conclusions sound familiar, it’s because they were first in the news last summer, when Hansen and his 18 co-authors—all climatologists, geologists, or academic scientists in their own right—released the paper online before it was peer reviewed. They said that the paper’s findings were too urgent, and the United Nations climate negotiations that December too imminent, to wait for the complete publication process.
“Given the inertia of the climate and energy systems, and the grave threat posed by continued high emissions, the matter is urgent and calls for emergency cooperation among nations,” they wrote, in the paper’s conclusion.
This was not always a clean process, or a process where reporters could be sure they were publishing scientifically vetted information. Andrew Revkin, the Times writer who followed the public peer-review process from the beginning, has argued since last summer that the study’s unusual method of well-publicized publication could lead to “whiplash, at best, and confusion and disengagement at worst.”
And indeed, we had better. Hansen and his team’s predictions are grave. They are out in public again, describing the potential consequences of their findings. Hansen himself posted a video explaining the science of the paper this week. If you’re interested in climate change and the planet, it’s worth watching: He brings together his scientific conclusions with what he believes are the right political actions.
At the heart of the findings is his argument that cold meltwater from Greenland is weakening an important internal current in the Atlantic Ocean, called AMOC, that keeps weather across the entire planet temperate. Once this current is shut down, then the Atlantic near the Arctic will stay cold and heat will build up in the southern latitudes, creating the potential for extreme weather of mythical proportions.
“I believe we are already watching the beginning of this cooling, southeast of Greenland,” Hansen says. “In that case, extra cooling and extra warming along the United States East Coast are not natural fluctuations. The warm water is the reason that [Hurricane] Sandy retained hurricane-force winds up to the New York City area.”
“Have we passed a point of no return? I doubt it, but it’s conceivable,” he adds. “But if we wait until the real world reveals itself clearly, it may be too late to avoid sea-level rise of several meters and loss of all coastal cities.”
The haste that Hansen is calling for here feels like a major change in how experts talk about climate to the public—a change perhaps as significant as Al Gore’s An Inconvenient Truth, 10 years old this May. It’s in line with how the Syrian civil war has been increasingly tied to the consequences of climate change; or the ways that public figures—including Miami’s Republican mayor—speak about global warming as a thing happening now instead of in the future. Hansen is trying to wage a public campaign on behalf of science, using scientific events as news pegs.
I think that is indispensable, noble work. It’s the work that Hansen left NASA to do. But as a public consumer of science, it’s important to recognize that this study represents just one scientific finding. Now that Hansen’s findings have been published, they will be tested and vetted and re-checked. Notably, they do not carry the imprimatur of, say, the UN’s Intergovernmental Panel on Climate Change, which releases consensus reports about the best available science. In fact, that is part of the point: Hansen and his team believe they’ve found mechanisms that more popular climate models, including those used by UN teams, don’t take into account.
As such, there is a public responsibility to communicate them clearly. If some of Hansen’s most ambitious arguments prove wrong, it will not invalidate the entire global-warming mechanism. It will not make the need to reduce fossil-fuel use any less dire. It will just mean that the near-term timeline looks somewhat different.
The world Hansen and his colleagues describe reads like a sci-fi plot synopsis—and it’s now officially part of the scientific canon (though peer review doesn’t necessarily guarantee that a paper is infallible). If Hansen and his colleagues are correct, this paper is likely one of the most important scientific contributions in history—and a stark warning to world governments to speed up the transition to carbon-free energy.
Hansen’s paper does read like science fiction—in fact, more than one journalist has compared it to The Day After Tomorrow. But to describe it as “officially part of the scientific canon” is so overstated as to tend toward meaninglessness. Hansen’s paper is scary, ambitious, fascinating, wide-ranging, well-sourced, and very newsworthy—but it’s just another peer-reviewed scientific paper. The peer review and publication process catches many errors, but it does not guarantee anything close to infallibility. (Consider the “replication crisis” now ripping through academic psychology: a controversy entirely about all the errors allowed to seep through peer review.) Right now, Hansen’s paper is exactly “officially” as much a part of “the scientific canon” as this paper on “feminist glaciology” or this more serious one on murderous prairie dogs.
This is not to downplay Hansen’s findings—their seriousness, their veracity, or their urgency. It’s not to diminish the climate emergency, either. Talking about something so worrisome, with margins of error so large, on deadline, in public, is hard. I am not guiltless of sensationalizing climate news. Late last year, I cited a science-fiction writer and climate activist while covering a series of unusually warm storms over the Arctic. I implicitly framed him as someone with a claim to scientific expertise that he didn’t have.
But this is a new era in climate communications, one in which scientists will try to assert the necessity of action as much as politicians or activists. It is critical that, while giving researchers their prized place in the public sphere, we do not overstate or sensationalize their findings. As journalists, as people speaking in public, and as concerned and vulnerable participants in the Earth system, we owe it to each other to get this right.