Increased aridity at the end of the Eemian in the Levant and relationships to global climate

Thick layers of halite deposited in the Dead Sea at the end of MIS 5e, revealed by the ICDP Dead Sea Deep Drilling Project cores, indicate extremely arid conditions prevailing in the Levant . Average precipitation during this interval was 50% of the present, and there were strong fluctuations between wetter periods similar to the present-day lasting on the order of millennia, and drought periods with precipitation as low as 20% of the present-day lasting on the order of centuries. At the same time, there were infrequent but intense rainfall events in the southern Levant and flash floods. U-series ages indicate that the hyper-arid conditions prevailed between 120-110 ka, following the `Eemian' Northern Hemisphere insolation peak interval of MIS 5e, and coinciding with decreased high latitude temperatures and atmospheric CO2 (Jouzel et al. 2007, Bereiter et al. 2015). Such conditions are consistent with pollen records from southern Europe indicating that region was warm until 110 ka (Brauer et al., 2007). The hyper-arid interval in the Levant followed a relatively wet period during the Eemian, coinciding with an intense African monsoon and major sapropel deposition in the eastern Mediterranean. Climate models indicate increasing aridity in the Levant between 125 ka and 120 ka; while at 125 ka there was significant summer and winter precipitation, 120 ka was drier than the present. The Levant in the present-day has a Mediterranean climate with dry summers and wet winters, where warmer winters coincide with lower precipitation. While the time interval of 120 ka to 110 ka, following the Eemian, was characterized by decreasing summer insolation, winter insolation increased. This increase in winter insolation may have caused a decrease in the sea-land temperature gradient that resulted in decreased precipitation on land. Bereiter, B. et al., 2015, Antarctic Ice Cores Revised 800KYr CO2 Data Brauer, A et al., 2007, Evidence for last interglacial chronology and environmental change from Southern Europe.: Proceedings of the National Academy of Sciences of the United States of America, v. 104, no. 2, p. 450-455 Jouzel, J. et al., 2007, Orbital and millennial Antarctic climate variability over the past 800,000 years.: Science (New York, N.Y.), v. 317, no. 5839, p. 793-6