Constraints on the Dead Sea levels based on Mg2+ budget since the last deglaciation

The Levant region of the Eastern Mediterranean is projected to experience increased drought due to rising greenhouse gas emissions. Proxy-based paleoclimate reconstructions are crucial for understanding natural hydroclimate variability, which is essential for constraining future hydroclimate changes in response to a globally warmer climate. Here, we reconstruct the lake levels of the Dead Sea in the southern Levant—currently comprising a deep north subbasin (∼300 m) and a shallow south subbasin (a few meters)—using pore-fluid Mg 2+ concentrations from the Dead Sea Deep Drilling Project (DSDDP) since the last deglaciation in combination with lake hypsometry. The Mg 2+ -deduced lake levels are ∼50–100 m higher than those inferred from published onshore records for the period ∼18–8 ka. We evaluated uncertainties arising from the published lake-level indicators, the Mg 2+ budget and the influence of basin bathymetric evolution on the applicability of the hypsometric curve. Our results show that the Mg 2+ removal through authigenic mineral formation is negligible, confirming it behaves as a first order tracer of lake-water balance. Correcting for well-constrained north basin paleo-bathymetry explains only part of the discrepancy (∼10–30 m). To resolve the remaining offset, we developed a dual Mg 2+ inventory model, which suggests that the separate south basin was much deeper during ∼18 to 8 ka and served as an important Mg 2+ reservoir. The dual inventory model incorporates plausible ranges for the subsidence rates of the north basin, Mg 2+ concentrations in the Dead Sea water bodies, and south basin size, yielding a range of lake-level estimates that propagates all of these uncertainties. The corrected Mg 2+ -based lake levels are consistent with previous reconstructions, leading to the development of a comprehensive lake-level compilation since the last deglaciation. The new lake level curve identifies three major droughts, at ∼13.7 ka, 11.7–11.3 ka, and ∼8 ka, associated with weakened Mediterranean cyclones caused by the intensification of the North Atlantic latitudinal sea surface temperature gradient following meltwater release events. Based on modern rainfall and discharge records in the watershed, the total freshwater discharge during these low stands was ca. 600–800 million m 3 /y, accounting for ∼30–50% of the pre-1960s value (prior to human-induced diversion), with the average Jerusalem rainfall dropping below 300 mm/y. The findings highlight potential challenges and considerations for future water resource management in the populated southern Levant.