Humanity’s risk of extinction ‘perils unexplored’

August 3, 2022 at 1:43 pm,
Updated on August 4, 2022 at 09:34

Reading time: 3 minutes

Climate Science

We need to advance the science of climate disaster ! This is the surprising invitation launched by climatologists to their colleagues, in the scientific journal. PNAS (Journal of the United States Academy of Sciences) August 1. Climate change could lead to the collapse of global society, even the extinction of humanity ? wondered Luke Kemp and his co-authors. Currently, this topic is not well explored. Yet there are many reasons to believe that climate change could lead to global catastrophe. »

Luke Kemp is a researcher at the Center for the Study of Existential Risk, University of Cambridge, dedicated to studying and mitigating risks that could lead to the extinction of humanity or the collapse of civilizations ». In their article, the researchers observed that the IPCC (Intergovernmental Panel on Climate Change) did little to study what would happen if global warming exceeded 3°C compared to the pre-industrial era. The IPCC is actually focused on warming of 1.5°C or 2°C.

Warming of 4.5°C has not been ruled out

This caution is understandableaccording to researchers, but it is not adapted to the risks and potential damages caused by climate change. […] The stakes are too high to not consider low-probability, high-impact scenarios. The Covid-19 pandemic highlights the need to consider and prepare for non-permanent, high-impact global risks and the systemic risks they can bring. »

This behavior is more realistic because researchers point out that the current trajectory of greenhouse gas emissions will lead to global warming from 2.1 ° C to 3.9 ° C by 2100. remains at the level of warming related to greenhouse gas concentrations, so that the possibility of a rise of 4.5°C by 2100 cannot be excluded.

Additionally, one may reach thresholds, or tipping points (tipping points) such that irreversible effects occur, linking each other, and amplifying without possible limit. Researchers discuss the melting of the Arctic ice, the release of carbon in the Amazon rainforest [1], the loss of efficiency of carbon sinks such as the ocean. They are still worried about a chain as many transition elements interact, shifting one threshold increases the probability of shifting another threshold ». The overall system can behave in unexpected ways, they point out: The increase in temperature depends very much on the global dynamics of the Earth system, and not only on the trajectory of anthropogenic emissions. »

Don’t think the worst” is deadly madness »

The question is clearly not only about the ecosystem. Climate changes can cause other disasters, such as wars, pandemics, famines… Researchers point out that today, only 0.8. % of the earth’s surface, and 30 million people, are subject to an average annual temperature of more than 29°C ; but that, according to the IPCC’s medium-high scenario of emissions and population growth, about 2 billion people are expected to live in 2070 in these extremely hot areas.

In conclusion, the scientists recommend the launch of a new research program that analyzes the extreme states of the Earth system, the possible events of high mortality and disease, the weaknesses of the society that may lead them to collapse or war, the possible sequence of disasters of various kinds. A program that can be called Climate: late game », according to the title of the article. And to conclude: Facing a future marked by the acceleration of climate change without considering the most pessimistic scenarios is, at best, naive risk management and, at worst, fatal folly. »

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