‘dangerously underexplored’ human extinction risk

‘dangerously underexplored’ human extinction risk

The risk of global society collapse or human extinction has been “dangerously under-explored,” climate scientists warned in an analysis.

They call such a catastrophe the “end of the climate game”. Although it had a small chance of it happening, given the uncertainties about future emissions and the climate system, catastrophic scenarios could not be ruled out, they said.

“Dealing with an accelerating future of climate change while blind to worst-case scenarios is naive risk management at best and fatally foolish at worst,” the scientists said, adding that there were “ample reasons” to suspect warming. global could cause an apocalyptic disaster.

The international team of experts argues that the world must start preparing for the possibility of the end of the climate game. “Analyzing the mechanisms of these extreme consequences could help galvanize action, improve resilience and inform policy,” they said.

Explorations in the 1980s of the nuclear winter that would follow a nuclear war spurred public concern and disarmament efforts, the researchers said. The analysis proposes a research agenda, which includes what they call the “four horsemen” of the end of the climate game: famine, extreme weather, war and disease.

They also asked the Intergovernmental Panel on Climate Change to produce a special report on the issue. The IPCC report on the impacts of just 1.5 ° C of warming sparked “a wave of public concern,” they said.

“There are many reasons to believe that climate change can become catastrophic, even at modest warming levels,” said Dr Luke Kemp of the University of Cambridge’s Center for the Study of Existential Risk, who conducted the analysis. “Climate change has played a role in every mass extinction event. It aided the fall of empires and shaped history.

“The paths to disaster are not limited to the direct impacts of high temperatures, such as extreme weather events. Chain effects such as financial crises, conflicts and new epidemics could trigger other calamities ”.

The analysis is published in the Proceedings of the National Academy of Sciences and has been reviewed by a dozen scientists. He argues that the consequences of global warming beyond 3 ° C have been underestimated, with few quantitative estimates of the total impacts. “We know less about the scenarios that matter most,” Kemp said.

A thorough risk assessment would consider how risks spread, interact and amplify, but it has not been attempted, the scientists said. “Yet that’s how real-world risk develops,” they said. “For example, a cyclone destroys electrical infrastructure, leaving a population vulnerable to a subsequent deadly heatwave.” The Covid pandemic underscored the need to look into rare but high-impact global risks, they added.

Of particular concern are the tipping points, where a small rise in global temperature translates into a large change in climate, such as huge carbon emissions from an Amazon rainforest suffering from severe droughts and fires. The tipping points could trigger others in a waterfall, and some remained poorly studied, they said, such as the abrupt loss of layers of cumulus layers that could cause an additional 8 ° C of global warming.

Researchers warn that climate collapse could exacerbate or trigger other catastrophic risks, such as international wars or infectious disease pandemics, and worsen existing vulnerabilities such as poverty, crop failure and water shortages. The analysis suggests that superpowers may someday fight over geoengineering plans to reflect sunlight or the right to emit carbon.

“There is a surprising overlap between currently vulnerable states and future areas of extreme warming,” the scientists said. “If the current political fragility does not improve significantly in the coming decades, a belt of instability with potentially serious ramifications could arise.”

There were other good reasons to be concerned about the potential for a global climate catastrophe, the scientists said: “There are warnings from history. Climate change has played a role in the collapse or transformation of numerous previous societies and in each of the five events of mass extinction in the history of the Earth ”.

Related: The domino effect of climatic events could bring the Earth into a “greenhouse” state.

New modeling in the analysis shows that extreme heat, defined as an average annual temperature above 29 ° C, could affect 2 billion people by 2070 if carbon emissions continue.

“Such temperatures currently affect about 30 million people in the Sahara and the Gulf coast,” said Chi Xu, of the University of Nanjing in China, who was part of the team. By 2070, these temperatures and the social and political consequences will directly affect two nuclear powers and seven maximum containment laboratories that house the most dangerous pathogens. There is serious potential for disastrous ripple effects. “

The current trend in greenhouse gas emissions would cause an increase of 2.1-3.9 ° C by 2100. But if the existing action commitments were fully implemented, the range would be 1.9-3 ° C. Achieving all the long-term goals set to date would mean 1.7-2.6 ° C of warming.

“Even these optimistic assumptions lead to dangerous trajectories of the Earth system,” said the scientists. Temperatures more than 2 ° C above pre-industrial levels had not been maintained on Earth for more than 2.6 million years, they claimed, long before the rise of human civilization, that it had grown up in a “restricted climate envelope” in the past 10,000 years.

“The more we learn about how our planet works, the greater the cause for concern,” said prof. Johan Rockström, at the Potsdam Institute for Climate Impact Research in Germany. “We increasingly understand that our planet is a more sophisticated and fragile organism. We have to deal with the disaster to avoid it. “

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