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Atlantic Rainfall Drives Lake-Filling Events in Sahara Desert

Science and Technology

Business Honor
24 March, 2025

New research reveals Atlantic-origin rainfall drives lake-filling events in the Sahara, challenging past climate theories.

New ETH Zurich, Hebrew University, and University of Bern research has revealed key findings on the meteorological processes behind lake-filling events in the northwestern Sahara, contradicting earlier assumptions about the climate history of the region. The study published in Hydrology and Earth System Sciences, indicates that Atlantic Ocean high-intensity rain, and not equatorial origins, is the primary reason for these anomalous lake formations.

The research specifically targets western Algeria's Sebkha El-Melah lake, a typical dry lakebed filled at times by devastating meteorological phenomena. The researchers found in their research that despite the basin of the lake having experienced hundreds of rainstorms from the 2000-2021 timeframe, there were only six massive episodes of lake-filling. These events were largely initiated by strong systems of Atlantic-sourced precipitation that were induced by extratropical cyclones in combination with upper-atmospheric environmental conditions, thus creating long-duration storms. Also influential were recycling-dominoes in which moistures were gradually carried and improved upon over the Sahara.

This new discovery refutes the long-standing theory that ancient lakes in the Sahara were supplied mostly by monsoonal rainfall from the south. Rather, the research brings into focus the key contribution of storms originating in the Atlantic, skipping the Atlas Mountains and directly supplying moisture into the desert.

The study has important implications for predicting how climate change can affect the water resources of the Sahara. Greater frequency and intensity of rainfall can result in more frequent filling of lakes in the future, changing water availability in one of the planet's driest regions. The research offers important lessons for climate researchers and hydrologists, presenting a new dimension on how climate change can remold the hydrological dynamics and ecosystem of the Sahara in the near future.