Present and future land surface and wet bulb temperatures in the Arabian Peninsula

The Arabian Peninsula exhibits extreme hot summers and has one of the world's largest population growths. We use satellite observations and reanalysis as well as climate model projections to analyze morning and evening land surface temperatures (LSTs), to refer to processes at the surface, and wet bulb temperatures (WBTs) to measure human heat stress. We focus on three regions: the Persian Gulf and Gulf of Oman, the inland capital of Saudi Arabia, Riyadh and the irrigated agricultural region in Al-Jouf, Saudi Arabia. This study shows that the time of day is important when studying LST and WBT, with current and future WBT higher in the early summer evenings. It also shows that the effect of humidity brought from waterbodies or through irrigation can significantly increase heat stress. Over the coasts of the Peninsula, humidity decreases LST but increases heat stress via WBT values higher than 25 degrees C in the evening. Riyadh, located in the heart of the Peninsula has lower WBT of 15 degrees C-17.5 degrees C and LST reaching 42.5 degrees C. Irrigation in the Al-Jouf province decreases LST by up to 10 degrees with respect to its surroundings, while it increases WBT by up to 2.5 degrees. Climate projections over the Arabian Peninsula suggest that global efforts will determine the survivability in this region. The projected increase in LST and WBT are +6 degrees C and +4 degrees C, respectively, in the Persian Gulf and Riyadh by the end of the century, posing significant risks on human survivability in the Peninsula unless strict climate mitigation takes place.