Probabilistic projections of increased heat stress driven by climate change

The Heat Index is a metric that quantifies heat exposure in human beings. Here, using probabilistic emission projections, we show that changes in the Heat Index driven by anthropogenic CO2 emissions will increase global exposure to dangerous environments in the coming decades. Even if the Paris Agreement goal of limiting global warming to 2 degrees C is met, the exposure to dangerous Heat Index levels will likely increase by 50-100% across much of the tropics and increase by a factor of 3-10 in many regions throughout the midlatitudes. Without emissions reductions more aggressive than those considered possible by our statistical projection, it is likely that by 2100, many people living in tropical regions will be exposed to dangerously high Heat Index values during most days of each typical year, and that the kinds of deadly heat waves that have been rarities in the midlatitudes will become annual occurrences. Exposure to dangerous heat index levels will likely increase by 50-100% in the tropics and by a factor of 3-10 in the mid-latitudes by 2100, even if the Paris Agreement goal of limiting warming to 2 degrees C is met, according to probabilistic projections of global warming.

Automated summary

Using probabilistic emission projections, this study demonstrates that the Heat Index driven by anthropogenic CO2 emissions will increase global exposure to dangerous environments in the future. Even if the Paris Agreement goal of limiting global warming to 2 degrees C is achieved, the exposure to dangerous Heat Index levels is projected to rise significantly, particularly in tropical regions. Without more aggressive emissions reductions, it is predicted that by 2100, many people in tropical regions will experience dangerously high Heat Index values on a daily basis, and deadly heat waves will become annual occurrences in mid-latitude regions.