Paleoclimate Evidence of Significant Eastern Mediterranean Aridity During Interglacial Periods: Implications for the Projected Drying Trend

Extended salt deposits, indicative of pronounced aridity, are preserved in a 220,000-year sediment core from the Dead Sea in the eastern Mediterranean Levant. These arid intervals occur in the warm interglacial periods of Marine Isotope Stages (MIS) 7, 5, and in the Holocene, and coincide with maxima in the Northern Hemisphere fall precession cycle. Similar salt layers are also present during the current and penultimate deglaciations. In insolation-driven climate model simulations, the North Atlantic latitudinal surface temperature gradient intensifies in the subsequent winter when boreal fall precession reaches a maximum. A lag that is due to the inherent delay in the upper ocean response. The enhanced surface temperature gradient leads to a shift the North Atlantic eddy-driven jet stream poleward, a decrease in polar sea-level pressure and an increase subtropical sea-level pressure. A weakening in the Mediterranean winter storm track occurs and a reduction in the rainfall over the Basin. Abrupt subpolar cooling events during recent and penultimate deglaciations—driven by ice sheet melt—similarly amplify the North Atlantic latitudinal surface temperature gradient, eliciting a comparable atmospheric response and similar rainfall reductions in the eastern Mediterranean. The late Quaternary palaeohydrology of the Dead Sea thus highlights an important North Atlantic ocean-atmosphere interaction that drives eastern Mediterranean droughts. A similar link exists between the changes in the North Atlantic Basin and the eastern Mediterranean rainfall trend in recent history and helps understand CMIP6 inter-model differences in their projected eastern Mediterranean drying.