CAMBRIDGE, United Kingdom — The world needs to prepare for humanity’s extinction because of climate change, according to a shocking new study. Scientists say global warming could become “catastrophic” for humanity if temperatures rise by even more than they are predicted to, or if the rising temperatures set off an unpredictable chain of events in nature.
The team, led by Cambridge University academics, says people should prepare for horror scenarios ranging from the loss of 10 percent of the world’s population to the end of all human life on Earth.
The researchers say the consequences of more than 5.4°F of global warming, compared with pre-industrial times, have not been explored well enough by previous studies. Last year’s IPCC report suggested that if atmospheric CO2 doubles from pre-industrial levels – something the planet is halfway towards – then there is around an 18-percent chance that temperatures will rise beyond 8.1°F.
The world is on track for 5.2°F of warming by the year 2100 if governments’ existing polices — as opposed to pledges they have made — continue without change, according to Climate Action Tracker. Scientists say 2.7°F is a safe level of heating.
The ‘four horsemen’ of climate change
The team is calling for new research to focus on the “four horsemen” of the climate endgame: famine and malnutrition, extreme weather, conflict, and vector-borne diseases.
Rising temperatures increase the risk of crop failures in the world’s most fertile agricultural areas. Meanwhile, hotter weather could cause outbreaks of deadly new diseases as habitats for both people and animals shift and shrink.
The authors say catastrophic warming will also make other existing threats worse, including rising inequality, misinformation, democratic breakdown, and even new forms of destructive AI weaponry.
They add that technologically advanced superpowers may end up fighting each other in “warm wars,” where they fight over dwindling carbon space and even fund expensive experiments to deflect sunlight and reduce global temperatures.
Researchers need to better understand tipping points that could spark disaster, such as melting permafrost that releases methane, the loss of forests that store carbon, and even cloud cover, the team argues.
‘Climate change has played a role in every mass extinction event’
They are calling on the Intergovernmental Panel on Climate Change (IPCC) to compile a report on catastrophic climate change in a bid to galvanize research and better inform the public.
“There are plenty of reasons to believe climate change could become catastrophic, even at modest levels of warming,” says lead author Dr. Luke Kemp from Cambridge’s Centre for the Study of Existential Risk in a media release.
“Climate change has played a role in every mass extinction event. It has helped fell empires and shaped history. Even the modern world seems adapted to a particular climate niche.”
“Paths to disaster are not limited to the direct impacts of high temperatures, such as extreme weather events. Knock-on effects such as financial crises, conflict, and new disease outbreaks could trigger other calamities, and impede recovery from potential disasters such as nuclear war,” Dr. Kemp continues.
“We know that temperature rise has a ‘fat tail’, which means a wide range of lower probability but potentially extreme outcomes. Facing a future of accelerating climate change while remaining blind to worst-case scenarios is naive risk-management at best and fatally foolish at worst.”
‘We know least about the scenarios that matter most’
Models show extreme heat, where the mercury reaches more than 84°F on a typical day, could affect two billion people by 2070. The affected areas are not just some of the world’s most densely populated, they are also some of the most politically fragile.
Two nuclear-armed countries will be this hot within less than 50 years and seven labs containing some of the world’s most dangerous pathogens will operate in sweltering heat.
Earlier research which compared and analyzed IPCC reports found scientists have shifted away from high-end warming to increasingly focus on lower temperature rises. In earlier studies, Kemp said extreme temperature rises are “underexplored relative to their likelihood.”
The study author adds that, “we know least about the scenarios that matter most.”
“The more we learn about how our planet functions, the greater the reason for concern,” says co-author Prof. Johan Rockström, Director of the Potsdam Institute for Climate Impact Research.
“We increasingly understand that our planet is a more sophisticated and fragile organism. We must do the math of disaster in order to avoid it.”
The findings are published in the journal Proceedings of the National Academy of Sciences.
South West News Service writer Gwyn Wright contributed to this report.