Aridity shifts in the MENA region under the Paris Agreement climate change scenarios

This study assessed the future shifts in aridity in the Middle East and North Africa (MENA) region, considering the scenarios set by the Paris Climate Agreement. This is achieved by utilizing eight General Circulation Models (GCMs) from the latest Coupled Model Intercomparison Project (CMIP6) version, simulating temperature rise of 1.5 and 2.0 degrees C. Potential Evapotranspiration (PET) was estimated using the Penman-Monteith equation, and agricultural lands at risk of aridity were identified using CMIP6 land use data. All CMIP6 GCMs were downscaled to a spatial resolution of 1showed improved accuracy in simulating PET. The results indicated a 50% increase in rainfall for Sudan, Saudi Arabia, Jordan, the UAE, Iraq, Syria, Yemen, and Oman. Additionally, most areas exhibited a 5% increase in PET. However, under the 1.5 degrees C scenario, Libya, Algeria, Tunisia, Syria, Jordan, Morocco, and Mauritania were projected to experience a rainfall reduction of 25% and a rise in PET of 5%, leading to a drier climate. Conversely, Sudan, Saudi Arabia, UAE, Oman, Yemen, and Iraq showed a relatively higher increase in rainfall (up to 50%) compared to PET (up to 7.5%), resulting in a wetter climate. Algeria and Morocco are projected to transit from sub-humid to semi-arid, while Saudi Arabia, Sudan, and Yemen are from hyper-arid to arid, likely due to a higher increase in rainfall (50%) than PET (5%). The most significant projected aridity shift is from arid to semi-arid and from hyper-arid to arid in the near future. For SSP1-1.9, 48,000 km2 of agricultural land is projected to converse from humid to sub-humid, while 63,000 km2 from sub-humid to semiarid in the far future for both scenarios. The study revealed considerable uncertainty in projected shifts in aridity, where GCMs contributed 95.7 to 96.3% of this uncertainty and the SSPs the rest. The analyses indicated that the large agricultural land affected by the aridity shift is not only due to the changes in aridity but also to increased cropland throughout MENA. These changes in aridity and the conversion of agricultural land, even under restricted rise in temperature, have alarming implications for the future climate.