Some of the luxurious, lush suburbs of Nairobi justify the slogan that tourism promoters have given the Kenyan capital; ”The Green City under the Sun”. Quiet streets are lined by perfectly manicured lawns and shadowed by giant jacaranda trees.

Water, say some experts, is a much more likely reason for countries to go to war than oil, and in the largely arid countries along the river Nile in northeastern Africa, the lack of water risks bringing neighbours dangerously close to armed conflict. Egypt is the greatest user of the Nile waters and has been able to irrigate large parts of land to feed its people.

The Norwegian Nobel Committee’s choice to give this year’s peace prize to an environmentalist was not entirely uncontroversial. The Economist newspaper wrote after the announcement in October that ”Ms Maathai’s work, though admirable, is only distantly related to the prevention of war. There is little evidence that environmental factors cause full-scale wars”.