Reduced impacts of heat extremes from limiting global warming to under 1.5 °C or 2 °C over Mediterranean regions

Abstract

Heat extremes have a serious impact on humans and on agriculture around the world. As one of the prominent climate change ‘hot spots,’ the Mediterranean area, especially the eastern portion, is expected to be more vulnerable to heat exposure than other regions due to its high population density and urbanization rate. The Paris Agreement includes the goal of ‘holding the increase in the global average temperature to well below 2 °C above preindustrial levels and pursuing efforts to limit the temperature increase to 1.5 °C above preindustrial levels’. It is interesting to study how heat extremes would change in the Mediterranean area in a +1.5 °C and +2 °C global warming world and how they would impact humans and agriculture. Based on high resolution climate scenario data from Coordinated Regional Downscaling Experiment Mediterranean, we calculate several heat extreme indices to study heat extreme changes in the future. We found that in most Mediterranean areas, both daytime and nighttime heat wave intensity and frequency will have a robust increase in the 21st century compared with that of the historical period, with the most prominent areas located in northwest Africa, the Iberian Peninsula, Italy and Middle East. Meanwhile, nighttime heat waves should be garnering more attention because more moderate and extreme events happen in nighttime than in daytime. If the global warming level is limited to 2 °C or even 1.5 °C, the percentage of population exposed to dangerous events (especially one-in-20 year events) and yield loss from maize harvested areas may be much less in the future than the percentage affected during 3 °C warming period. Moreover, limiting global warming to 1.5 °C instead of 2 °C would result in an additional 20%–25% reduction of exposure.