Distinguished lectures in Earth Sciences - Lessons from the Past: Saharan perspectives on Global Warming


Società Geologica Italiana

Mercoledì 16 Ottobre ore 16:00
Aula Geo 1 – Edificio 10
Complesso Universitario di Monte S. Angelo

Università degli Studi di Napoli Federico II

Stefan Kröpelin, University of Cologne

The Sahara which equals the area of the USA is an ideal natural laboratory for studies of past climate and environmental change on the habitable continents. Undisputed geological and archaeological evidence shows that the last major global warming at the end of the ice age has resulted in a regreening of the planet's major hot desert. 11,000 years ago, the Sahara progressively turned into a savanna dotted with lakes and became home to big fauna and prehistoric people. Its vegetation and soil cover allowed for carbon sequestration of global proportion during several millennia. About 6,000-3,000 years ago, the verdant grasslands gradually turned into today's enormous wasteland. The decline in rainfall pushed residents south and east, and contributed to the rise of Egyptian civilization in the Nile Valley.
Taking the past as a key to the future and the regreening of the Sahara as a scenario, increasing global temperatures might lead to the rehabilitation of ~10 million km², one third of the African continent. Former climate shifts happened gradually over millennia—not over a mere century or two, as suggested by some scientists—, and challenge interpretations of ocean cores, numerical climate models or the concept of future "tipping points". The outlook at huge carbon sequestration in the Old World desert belt in case of sustained and substantial global warming is a not yet recognized aspect in the highly politicized discussion on anthropogenic climate change.
Stefan Kröpelin is a geologist and climate researcher who specializes in studying the Eastern Sahara of Egypt, Libya, Sudan and Chad, today the planet's largest hyperarid desert and perhaps the least explored place on Earth. Almost every year for four decades Kröpelin has made multi-month expeditions to figure out the palaeo-climatological changes and human saga in the region over the last 11,000 years. Kröpelin has also initiated and promoted natural and cultural conservation projects in the Sahara such as the Lakes of Ounianga and the Ennedi Massif listed as Chad's first UNESCO World Heritage sites.

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