High resolution environmental conditions of the last interglacial (MIS5e) in the Levant from Sr, C and O isotopes from a Jerusalem stalagmite

Abstract

The southern Levant region at the fringe of the Saharan-Arabian deserts is particularly vulnerable to warming and desertification, therefore reconstruction of the hydroclimate conditions of this region during periods of past climate change provide important insight on what may occur in the future. Here we report on high temporal resolution 87 Sr/ 86 Sr, δ 13 C and δ 18 O isotope data of a stalagmite from the Har Nof cave in Jerusalem, demonstrating major climate changes during the last interglacial MIS5e between ~131–116 ka. We combine also data from other caves in Israel and the ICDP Dead Sea deep drill core. The following palaeoenvironmental history is observed: • At 131–127.5 ka, Jerusalem experienced moderate Mediterranean climate conditions. Desert dust accumulated above the cave, while salt deposition occurred in the Dead Sea. • At 127.5–122 ka, across the MIS5e insolation peak and Sapropel S5 interval in the Mediterranean, highly negative speleothem δ 18 O indicate both Mediterranean and southern (tropical) derived rains. Surface cover diminished, and by 122 ka the 87 Sr/ 86 Sr and δ 13 C values indicate complete soil removal above the cave. Very high temperatures and intensive fires caused the removal of C 3 vegetation. The rainfall season shifted from winter to summer with tropical-sourced precipitation. • At 122–120.5 ka, the 87 Sr/ 86 Sr ratios indicate contributions of sea salts. Extremely high speleothem δ 13 C values indicate no vegetation. • At ~120.5–118 ka there was higher rainfall and lower temperatures, associated with re-establishment of vegetation, including savannah-like C 4 pioneer grasses that appeared on soil patches. • At 118–116 ka, the sedimentation rate of Har Nof AF12 stalagmite is extremely low, indicating regional aridity, coinciding with massive salt deposition in the Dead Sea. • Last interglacial unstable environment in the southern Levant is demonstrated. • Heat, fires and rainfall season shift caused loss of Mediterranean vegetation. • Tropical-sourced summer rains intruded the southern Levant. • Savannah-like vegetation replaced Mediterranean forest. • Reconstruction is based on speleothems, corroborated by models and Dead Sea records.