International risk of food insecurity and mass mortality in a runaway global warming scenario

Paper by Catherine Richards, Hannes Gauch, Julian Allwood
Published on 31 May 2023


Climate and agriculture have played an interconnected role in the rise and fall of historical civilizations. Our modern food system, based on open-environment production and globalised supply chains, is vulnerable to a litany of abiotic and biotic stressors exacerbated by anthropogenic climate change. Despite this evidence, greenhouse gas emissions continue to rise. Current trajectories suggest global warming of ∼2.0–4.9 °C by 2100, however, a worst-case emissions scenario with rapid combustion of all available fossil fuels could cause a rise of ∼12 °C. Even if emissions decline, unprecedented atmospheric CO2-e concentrations risk triggering tipping points in climate system feedbacks that may see global warming exceed 8 °C. Yet, such speculative ‘runaway global warming’ has received minimal attention compared to mainstream low- to mid-range scenarios. This study builds on The Limits to Growth to provide new insights into the international risk of mass mortality due to food insecurity based on a higher-resolution illustration of World3’s ‘runaway global warming’ scenario (∼8–12 °C+). Our simulation indicates rapid decline in food production and unequal distribution of ∼6 billion deaths due to starvation by 2100. We highlight the importance of including high-resolution simulations of high-range global warming in climate change impact modelling to make well-informed decisions about climate change mitigation, resilience and adaptation.

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