Climatologists have warned in a new report that too little work has been done to understand the risks global warming could pose to human survival.
The study’s authors said the potential for climate change to lead to global societal collapse or even human extinction is a “dangerously underexplored topic”.
According to the authors, even if the catastrophe is unlikely to occur, given the uncertainties about future emissions and the climate system, cataclysmic scenarios should not be ruled out.
“Dealing with a future of accelerating climate change while blind to worst-case scenarios is naïve and at worst fatally foolish risk management,” the scientists said, adding that there are “many reasons” to suspect that global warming could cause an apocalyptic catastrophe.
The international team of experts argue that the world must prepare for the possibility of a “climate endgame”. “Analyzing the mechanisms of these extreme consequences could help galvanize action, improve resilience and inform policy,” they said.
The in-depth analysis proposes a research agenda, which includes what the researchers call the “four horsemen” of the “climate finale”: famine, extreme weather, war and disease.
“There are many reasons to believe that climate change could become catastrophic, even at modest levels of warming,” said Dr Luke Kemp of the University of Cambridge’s Center for the Study of Existential Risk, who led analysis.
“Climate change has played a role in every mass extinction event. It helped bring down empires and shape history,” he added. “The paths to disaster are not limited to the direct impacts of high temperatures, such as extreme weather events. Ripple effects such as financial crises, conflicts and new epidemics could trigger other calamities.
A dozen scientists reviewed the analysis, published in the journal Proceedings of the National Academy of Sciences. He argues that the consequences of global warming beyond 3°C have been under-examined, with few quantitative estimates of total impacts.
Using climate models, the analysis shows that extreme heat – defined as an average annual temperature of over 29C – could affect two billion people living in some of the world’s most politically fragile regions by 2070, if carbon emissions continue.
“Such temperatures are currently affecting 30 million people in the Sahara and the Gulf Coast,” said Chi Xu, from Nanjing University 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 housing the most dangerous pathogens. There is serious potential for disastrous ripple effects.
According to the report, it is not just high temperatures that are the problem, it is compound and ripple effects such as food or financial crises, conflict or disease outbreaks that have the potential to cause disaster.
The researchers also pointed out that more focus should be placed on identifying potential tipping points, where increasing heat triggers another natural event that drives temperatures even higher – such as methane emissions from the melting permafrost or forests that begin to emit carbon rather than absorb it.
Carrying out the research would allow scientists to consider emergency options such as climate engineering that could involve pumping refrigerants into the atmosphere, the researchers say.
Furthermore, the analysis can also pave the way for researchers to perform a risk analysis of these drastic interventions versus the worst effects of climate change. Focusing on worst-case scenarios could also help inform the public – and could actually make outcomes less likely.
To properly assess all these risks, the team asks the Intergovernmental Panel on Climate Change to produce a special report on the issue. The IPCC’s report on the impacts of a warming of just 1.5°C has caused a “ground wave of public concern”, the researchers said.
“The more we learn about how our planet works, the more there is to worry about,” said Professor Johan Rockström, from the Potsdam Institute for Climate Impact Research in Germany. “We increasingly understand that our planet is a more sophisticated and fragile organism. We must calculate the disaster in order to avoid it.
Sign up for the E&T News email to get great stories like this delivered to your inbox every day.