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Published: 2022-09-13

Once there were lakes in the Sahara Desert

NEWS A recently published paper in Journal of Paleolimnology by among other, Christos Katrantsiotis at Umeå University, provide evidence for the existence of ancient lakes in the Sahara Desert.

Text: Per Melander

Understanding the variability of past climate can thus provide us with an insight into how Sahara could change in the future 

Christos Katrantsiotis points out that the Sahara Desert was not always a desert. Instead, it consisted of lakes and plants in the past.

– In this paper by Yahiaoui et al., we particularly provide evidence for the existence of ancient lakes dated between around 10.000 and 5.000 years ago in the northern Sahara, Algeria, says Christos Katrantsiotis and continues:

– Our method is based on the analysis of fossil algae found in the sand and deposited in aquatic environments million years ago when the area was covered by lakes.

The green Sahara

Christos Katrantsiotis says furthermore that the so-called Green Sahara or African Humid Period is a wet period in northern Africa that occurred during the last warm period of the Earth (Holocene) that started around 11.000 years ago due to changes in Earth's orbital parameters. 

– Understanding the variability of past climate can thus provide us with an insight into how Sahara could change in the future as return to conditions similar to the past warm period is possible due to anthropogenic warming.

Is there anything that surprised you in this study?

– This paper provides evidence for the existence of ancient lakes, deep in the Sahara Desert, far away from the Mediterranean coast, in an area which is today completely dry. But in the past, it was a completely different environment, with lakes and trees.

Previous studies, Christos Katrantsiotis says, have indicated that the reason for this wet period in Sahara was mainly expansion of summer monsoonal rains from the tropical regions in response to orbital forcing. 

– Here, we argue that the reason for this wet phase in the Algerian Sahara was the intensification of winter precipitation in the south-central Mediterranean and its penetration southward (to the ancient Sahara) associated with changes in oceanic and atmospheric circulations in the North Atlantic region. 

How will you continue, will there be any additional work in extension of this?

– In future studies, we will try to increase the dating accuracy in order to define more precisely the onset and termination of this wet period in Sahara. In addition, more samples will be analysed from new sites for a better understanding of the regional climatic conditions and the driving mechanisms behind the observed climatic changes.

The paper Early to Middle Holocene hydroclimate changes in the Guern El Louläilet depressions, Algerian Sahara is published in the Journal of Paleolimnology and is part of Christos Katrantsiotis collaboration with the Laboratory of Paleontology and Paleoenvironmental Research in University of Oran, in Algeria.

The research was performed by the Phd student, Nassima Yahiaoui, in Algeria while C Katrantsiotis from Umeå University contributed with data interpretation and the writing of the paper.