World advised to prepare for climate change endgames

The potential for global warming to cause catastrophic, humanity-ending events is "dangerously unexplored", according to an international team of climate experts that has called for governments and institutions to establish so-called climate endgame research agendas.

Public discourse around climate change is often centered on energy transition, and keeping warming to below 2 C. But a new paper in the journal Proceedings of the National Academy of Sciences suggests we neglect a more pessimistic view of the future at our peril.

"Climate change has played a role in every mass extinction event," said lead author Luke Kemp from the University of Cambridge's Center for the Study of Existential Risk. "It has helped fell empires and shaped history."

The doomsday scenarios put forth by researchers from China, the United Kingdom, Germany, and the United States involve climate targets being missed by wide margins, as well as natural and man-made disasters triggering a series of cascading events.

The team urged the Intergovernmental Panel on Climate Change to dedicate a future report to catastrophic climate change, which it hopes will galvanize research and inform the public. Such a report should consider outcomes ranging from a 10 percent loss of the global population to eventual human extinction.

Kristie Ebi, an epidemiologist from the University of Washington in the US who contributed to the research, said a greater appreciation of catastrophic climate scenarios can help compel public action.

The authors of the paper proposed a new research agenda that includes what they call the "four horsemen "of the climate endgame: famine and malnutrition, extreme weather, conflict, and vector-borne diseases.

"By 2070, these temperatures and the social and political consequences will directly affect two nuclear powers, and seven maximum containment laboratories housing the most dangerous pathogens," said Xu Chi, a researcher from Nanjing University who co-authored the paper. "There is serious potential for disastrous knock-on effects."

Modeling done by the team shows areas of extreme heat－or an annual average temperature of more than 29 C－could cover 2 billion people by 2070.