Climate change: The dramatic scenario for the end of humanity

Climate change could prove catastrophic for humanity if the rise in global temperatures is ultimately higher than expected (above three degrees Celsius compared to pre-industrial levels) or if it triggers a chain of events, a scenario that to date has "dangerously be overlooked," warns an international study led by scientists from the British University of Cambridge. Scientists are sounding the alarm that, however small the possibility of such a cataclysm may be, it cannot be ruled out, which is why the world "must start preparing for the possibility of a 'climate finale'".

The researchers, led by Dr. Luke Kemp of the Cambridge Center for the Study of Existential Risk, who published in the journal Proceedings of the National Academy of Sciences (PNAS) of the US National Academy of Sciences, propose a research agenda that it will lay out the worst possible scenarios, which range from a loss of 10% of the world's population to the eventual extinction of all humans due to the climate crisis. In this context, among other things, they call on the Intergovernmental Panel on Climate Change (IPCC) to dedicate a future report to the prospect of a catastrophic climate change, so that international public opinion can be mobilized more actively.

Based on current "greenhouse gas" trends, most scientists expect an increase in average global temperatures of 2,1 to 3,9 degrees by 2100. If the necessary measures are more strictly adhered to by most countries, the rise it can be kept at 1,9 to 3 degrees, while in the optimistic scenario the temperature rise will not exceed 2,6 degrees.

"There are ample reasons to believe that climate change could become catastrophic, even with modest levels of temperature increase. Climate change has played a role in every mass extinction of species in the past. It has helped bring down empires and shaped history," said Kemp. “Pathways to disaster are not limited to the immediate effects of high temperatures, such as extreme weather events. Indirect consequences such as economic crises, conflicts and new disease outbreaks can trigger other risks and hinder recovery from potential disasters such as nuclear war,” he added.

The study estimates that by 2070 about two billion people will live in areas of extreme heat, with an average annual temperature above 29 degrees Celsius, compared to only 30 million today, mostly in the Sahara and the Gulf region. In fact, many of the areas in question will be densely populated and politically unstable.

Last year's IPCC report predicted that if carbon dioxide in the atmosphere doubles from pre-industrial levels (which half of what has happened so far), there is an 18% chance that global temperatures will eventually rise above 4,5 grades.

The new study finds that the IPCC reports do not give due weight to extreme scenarios. "We know very little about the very scenarios that matter most," Kemp said. That is why he stressed that more scientific attention should be paid to the so-called "four knights" of the climate crisis (by analogy with the knights of the Christian Apocalypse): malnutrition and hunger, extreme weather, war conflicts and infectious diseases.

The study highlights that, among other things, rising temperatures pose a major threat to the global food supply, while increasingly frequent extreme weather events create conditions for new pandemics. The researchers think it is likely that over time climate collapse will outweigh other threats, such as economic inequality, misinformation and the erosion of democracy.

The scientists point out that more emphasis needs to be placed on identifying all the potential critical tipping points in "Greenhouse Earth" that could trigger an uncontrolled climate trajectory, such as the massive release of methane from the heretofore permanently frozen Arctic regions or the large loss of forests, which currently absorb significant amounts of carbon, partially offsetting its increase in the atmosphere.

Professor Johan Rockström, director of Germany's Potsdam Institute for Climate Impact Research, said that “the more we learn about how our planet works, the greater the reasons for concern. We understand more and more that our planet is a more complex and at the same time vulnerable organism. We have to do the mathematical calculations of a possible disaster in order to avoid it."

"Facing a future of worsening climate change but remaining blind to worst-case scenarios is naive risk management at best and fatal folly at worst," Kemp said, summarizing the researchers' central message.

Source: RES-EAP