Increasing heat stress under different levels of global warming with WRF regional climate simulations for the MENA-CORDEX domain.

Abstract

<p class="western" align="justify">Heat extremes are expected to augment in frequency and magnitude due to global warming, with the Middle-East – North Africa (MENA) region emerging as a prominent climate change hotspot. In this study, we assess the future extreme heat conditions in the MENA region under various levels of global warming. For this, WRF high-resolution regional climate simulations (at 24 km grid size) are carried out for the MENA-CORDEX domain for different 20-year periods corresponding to the current climate and three global warming levels (+2°C, +3°C and +4°C relative to the pre-industrial period). The future changes for the annual warmest day (TXx) and night (TNx) are presented as well as the projected levels of humid heat through the analysis of the Heat Index (HI) and wet-bulb temperature (TW). Results generally indicate more intense warming over the northern part of the Mediterranean basin. For strong warming (+4°C), the indices of Warmest Day (TXx) and Warmest Night (TNx) are projected to increase by more than 6°C in the northern part of the domain. At 2°C of warming, areas around the Gulf are expected to experience extremely dangerous levels of humid heat, with Heat Index (HI) > 51° C, and Wet Bulb Temperature (TW) > 30° C. If global warming exceeds 2°C, the frequency and extent of heat extremes in the region will greatly increase, with some areas of the domain reaching the TW survivability limit of 35°C. Our research also suggests that heat events that currently occur once every 50 years may occur every few years at a global warming level of 2°C. At even higher warming, extremely dry and humid heat events are expected to occur multiple times per year.</p>