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Research project: Palaeolake Megachad research project

Image of Palaeolake bed Around 6000 years ago, this was the biggest lake in Africa and possibly the biggest freshwater lake on Earth with a surface area about the same as California, and bigger than all the Great Lakes of North America combined (Drake and Bristow 2006).

 

Now it is dry, providing dramatic testimony to climate change in Africa.
  • We are studying the sediments of palaeolake megachad to investigate the history of lake flooding and desiccation and associated climate change in north Africa.
  • We are also studying the lake bed geomorphology, sedimentology and sedimentary geochemistry, to determine the composition of the dust that is produced and the rates of deflation (Bristow et al. 2009). Around half of the dust from Palaeolake Megachad falls in the tropical Atlantic Ocean while another 20% reaches the Amazon Basin.

The dust contains iron and phosphorus which act as a fertiliser increasing productivity which is good news for Earth's climate because plants and algae help to remove CO2 from the atmosphere (Bristow et al. 2010).

This research forms part of a wider study of the Green Sahara.

Find out more

  • BoDEx website
  • Lovett, Richard African dust keeps Amazon blooming, Nature News, 9 August 2010.
  • Bristow, C.S., Hudson-Edwards, K., and Chappell, A., 2010, Fertilizing the Amazon and equatorial Atlantic with West African dust. Geophysical Research Letters Vol 37, doi: 10.1029/2010GL043486, 2010.
  • Drake, N., and Bristow, C.S., 2006, Shorelines in the Sahara: geomorphological evidence for an enhanced monsoon from palaeolake Megachad. The Holocene, 16, p.901-911.
  • Bristow, C.S., Drake, N., and Armitage, S., 2007, Deflation in the dustiest place on Earth: the Bodélé Depression, Chad, Geomorphology 105, p.50-58.