Future cost of climate change for humanitarian crises

Humanitarian crises are the tip of the iceberg in climate change adaptation, yet their future is rarely quantified in human and economic terms. We use machine learning to simulate future estimates of people in need of humanitarian aid and required funding under the middle-of-the-road scenario (SSP2-RCP4.5) with 2,7°C warming by end of the century. Humanitarian needs rise to a baseline of 410±22 million people and USD2024 64±8 billion annually by 2050 worldwide, increases of 127% and 130% respectively compared to 2024 (323 million people and USD 49 billion). A medium optimistic simulation holds needs near the current, while a medium pessimistic simulation leads to 614±68 million people and USD2024 96±19 billion by 2050, increases of 190% and 196% respectively. Our results show empirical vulnerabilities and an opportunity cost, as resources for crisis response displace funding for adaptation and mitigation. Yet sustained investment could curb the impacts even with climate inertia.