Increased Heat Waves and Extremes with Associated Population Risk in a CO2-Warmed World

The severest impacts of climate change come not from meteorological conditions near average, but from extreme events. In this analysis, we analyze an ensemble of 28 runs of the Max Plank Institute Earth System Model (version 1.1) forced by CO₂ increasing at 1%/year. We focus on how heat waves and humidity extremes evolve as the climate warms. Indices based on relative and absolute criteria has been set up to evaluate the extreme events. All extreme heat indices tend to increase, with distinct spatial characteristics. The frequency of heat wave showed the largest increase in Southeast Asia and Tropical West Pacific, while the amplitude of heat waves showed the largest increase in high latitude regions such as Russia and Canada. Associated increases were merged to population data to show that the most abrupt increase of heat-related human risk will happen between 1.5°C and 3.0°C of global warming.