Potential heat-risk avoidance from nationally determined emission reductions targets in the future

The increasing heat stress from the combined effect of changes such as temperature and humidity in the context of global change receives growing concerns. However, there is limited information for future changes in heat stress, as well as its potential socioeconomic impact, under the intended nationally determined mitigation scenarios. This study established an efficient evaluation method to quantify the benefits from the potential heat stress reduction from a continued intended nationally determined contributions (INDC) mitigation effort. The future heat stress over global land, quantified by the wet bulb globe temperature, was investigated based on the temperature sensitivity approach and multi-model simulations from the latest generation global climate models. The INDC continuous-effort scenario and the delayed-effort scenario, as well as the target-control scenarios of 2 degrees C warming, were compared. We found that with the delayed mitigation efforts, the increase in frequency, duration, and cumulative intensity of extreme heat stress relative to the INDC continuous-effort scenario in the late 21st century could reach to 113%, 193%, and 212%, respectively. If more ambitious efforts above current INDC pledges were implemented to achieve the 2 degrees C global temperature goal, the corresponding avoided impact of heat stress frequency, duration, and cumulative intensity in the late 21st century was estimated to be 32%, 37%, and 40%, respectively. Future changes in heat stress in low latitudes, where most developing countries are located, are most sensitive to emission reduction. Our results highlighted the potential avoided heat stress-related impact of global warming from efforts towards climate change mitigation.

Automated summary

This study established an efficient evaluation method to quantify the benefits from the potential heat stress reduction. Results showed that delayed mitigation efforts could greatly increase the frequency, duration, and intensity of extreme heat stress, while more ambitious efforts could significantly reduce the impact of heat stress. Low latitude regions, where most developing countries are located, are most sensitive to emission reduction.