Rainfall changes in Africa one thousand years ago

What is it about?

In this paper we are describing shifts in precipitation that occurred in Africa 1000-1200 AD during the so-called Medieval Climate Anomaly. The study identified three areas in Africa in which rainfall increased during the Medieval Climate Anomaly, namely Tunisia, western Sahel and the majority of southern Africa. At the same time, a reduction in precipitation occurred in the rest of Africa, comprising of Northwest and Northeast Africa, West Africa, Eastern Africa and the Winter Rainfall Zone of South Africa. The latter region includes Cape Town that currently suffers from a multi-year drought that has led to a serious shortage of drinking water. Similar droughts appear to have existed here during medieval times when the rain-bearing westerly winds were pushed so far south and away from land that they no longer intercepted the continent.

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Why is it important?

Changes in rainfall are a key characteristic of the modern climate system on decadal to millennial time scales. In order to better understand the natural component of such changes and their drivers, it is important to study the pre-industrial hydroclimate history. The African review reminds us that droughts such as presently occuring in the South African Cape Province have also previously occurred and that we need to fully understand their origin in order to better predict their occurence and be prepared for such phases.

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