Long‐Term Variability in the Arabian Peninsula Droughts Driven by the Atlantic Multidecadal Oscillation.

Drought is a recurring hydroclimatic extreme over the Arabian Peninsula (AP). So far, no study has examined the changes in drought characteristics in recent decades, not to mention the background mechanisms for such changes. To this end, analyzing the Standardized Precipitation Evapotranspiration Index (SPEI) mainly from the European Reanalysis (ERA5) data sets, in addition to other observational/reanalysis data sets over the period of 1951–2020, we show that droughts over the AP have increased in frequency and severity over the last two decades. We show that this drought acceleration, which was not observed in the previous 40–50 years, is a combination of decadal variability and long‐term trends. Importantly, we demonstrate that the decadal SPEI variability is due to the Atlantic Multidecadal Oscillation (AMO). The unprecedented multiyear drought over the AP in recent decades is evidently associated with the current positive phase of the AMO. We also show that the recent warming of the AP is a more significant factor in the drought intensification than the concurrent weakening of local precipitation. Furthermore, we developed a machine learning model largely based on the observed AMO–SPEI relationship. This model predicts a reduced drought severity over the AP in the near future. Plain Language Summary: Our study shows that the drought frequency and severity have increased over the Arabian Peninsula (AP) in the last two decades relative to the preceding five decades. This recent drought intensification exhibits a dominant decadal variability in addition to what appears to be a long‐term trend. Enhanced warming over the AP appears to be a larger factor for the current drought intensification than the weakening of local precipitation. The decadal drought variability is strongly related to the Atlantic Multidecadal Oscillation (AMO) cycle, and the current unprecedented multiyear drought is associated with the current positive phase of AMO. We developed a machine learning model for future projections that suggests that the drought frequency and intensity over the AP are expected to weaken substantially in the next two to three decades. Key Points: Drought variability over the Arabian Peninsula (AP) is the manifestation of decadal variability and long‐term trendsThe enhanced warming over the AP is a dominant factor for drought intensity relative to the weakening of local precipitationThe phase change of the Atlantic Multidecadal Oscillation in the last two decades has caused unprecedented severe droughts over the AP [ABSTRACT FROM AUTHOR]