Experts are ignoring the worst possible catastrophic scenarios for climate change, including the collapse of society or possible human extinction, however unlikely, a group of leading scientists claims.
Eleven scientists from around the world are calling on the United Nations’ Intergovernmental Panel on Climate Change, the world’s authoritative climate science body, to hold a special scientific report on “catastrophic climate change” to “focus on how much is at stake for the worst case.” In their perspective in Monday’s Proceedings of the National Academy of Sciences, they address the idea of human extinction and global social collapse in the third sentence, calling it “a dangerously unexplored topic.”
Scientists said they are not saying the worst will happen. They say the problem is that no one knows how likely or unlikely a “climate endgame” is, and that the world needs these calculations to deal with global warming.
“I think it’s very unlikely that you’ll see anything close to extinction in the next century simply because humans are incredibly resilient,” said study lead author Luke Kemp at the Center for the Study of Existential Risk at the University of Cambridge in England. . “Even if we have a 1% chance of having a global catastrophe that will disappear in the next century, that 1% is too high.”
Catastrophic climate scenarios “appear likely enough to warrant caution” and can lead to prevention and warning systems, Kemp said.
Good risk analyzes consider both the most likely and the worst that could happen, the study authors said. But because of the push from non-scientists who reject climate change, mainstream climate science has focused on looking at the most likely and also disproportionately on low-temperature warming scenarios that approach international targets, said co-author Tim Lenton, director of the World Systems Institute at the University of Exeter in England.
Lenton said “not enough emphasis is placed on how things, the risks, the big risks, could reasonably go very wrong.”
It’s like an airplane, Lenton said. It’s overwhelmingly likely to land safely, but that’s only because so much care was taken to calculate the worst-case scenario and then figure out how to avoid a collision. It only works if you research what can go wrong, and that’s not being done enough with climate change, he said.
“The stakes may be higher than we thought,” said University of Michigan Dean Jonathan Overpeck, who was not involved in the study. He worries that the world “could be stumbling” into climate risks it doesn’t know about.
When global scientific organizations look at climate change, they tend to just look at what’s happening in the world: extreme weather, higher temperatures, melting ice, rising seas and extinctions of plants and animals. But they don’t take enough account of how these reverberate through human societies and interact with existing problems — such as war, hunger and disease — the study’s authors said.
“If we don’t look at the risks that intersect, we’re going to be painfully surprised,” said University of Washington professor of public health and climate Kristie Ebi, a co-author who, like Lenton, has been involved in the United Nations’ global climate assessments.
It was a mistake health professionals made before COVID-19 when evaluating potential pandemics, Eby said. They talked about the spread of disease, but not about lockdowns, supply chain problems and spiraling economies.
The study’s authors said they worry about social breakdown — war, famine, economic crises — linked to climate change more than physical changes on Earth itself.
Outside climate scientists and risk experts have been both welcoming and wary of focusing on the worst of the worst, even as many dismiss talk of climate doom.
“I don’t believe civilization as we know it will make it past this century,” climate scientist Andrew Weaver, a former British Columbia legislator for the Green Party, said in an email. “Resilient people will survive, but our urbanized societies supported by rural agriculture will not.”
Climate scientist Zeke Hausfather of the tech company Stripe and Berkeley Earth has criticized climate scientists in the past for using future scenarios of large increases in carbon pollution when the world is no longer on these paths to faster warming. But he said it’s reasonable to consider catastrophic scenarios “as long as we’re careful not to confuse the worst case with the most likely outcome.”
Talking about people disappearing is not “a very effective communication device,” said Kim Cobb of Brown University. “People tend to immediately say, well, that’s just, you know, hand-waving or bravado.”
What happens before the disappearance is bad enough, he said.
Co-author Tim Lenton said the worst-case scenario research could find nothing to worry about: “Maybe you can completely rule out some of these bad scenarios. Well, it’s really worth your time to do this. Then we should all be a little happy.”
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