Climate Endgame Exploring catastrophic climate change scenarios

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 119; no. 34; pp. 1 - 9
• Main Authors: Kemp, Luke, Xu, Chi, Depledge, Joanna, Ebi, Kristie L., Gibbins, Goodwin, Kohler, Timothy A., Rockström, Johan, Scheffer, Marten, Schellnhuber, Hans Joachim, Steffen, Will, Lenton, Timothy M.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 23.08.2022
• Subjects: Anthropogenic factors; Climate Change; Disaster Planning; Emergency preparedness; Emergency response; Forecasting; Humans; Mass extinctions; Morbidity; PERSPECTIVES; Physical Sciences; Political factors; Risk Management; Social Sciences; Species extinction; Anthropocene; Earth system trajectories; catastrophic climate change; tipping elements; climate change
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.2108146119

Prudent risk management requires consideration of bad-to-worst-case scenarios. Yet, for climate change, such potential futures are poorly understood. Could anthropogenic climate change result in worldwide societal collapse or even eventual human extinction? At present, this is a dangerously underexplored topic. Yet there are ample reasons to suspect that climate change could result in a global catastrophe. Analyzing the mechanisms for these extreme consequences could help galvanize action, improve resilience, and inform policy, including emergency responses. We outline current knowledge about the likelihood of extreme climate change, discuss why understanding bad-to-worst cases is vital, articulate reasons for concern about catastrophic outcomes, define key terms, and put forward a research agenda. The proposed agenda covers four main questions: 1) What is the potential for climate change to drive mass extinction events? 2) What are the mechanisms that could result in human mass mortality and morbidity? 3) What are human societies' vulnerabilities to climate-triggered risk cascades, such as from conflict, political instability, and systemic financial risk? 4) How can these multiple strands of evidence—together with other global dangers—be usefully synthesized into an “integrated catastrophe assessment”? It is time for the scientific community to grapple with the challenge of better understanding catastrophic climate change.