Everyday life in Mali. Image by Inez Forbes, © UNESCO
The new edition of UNESCO's science magazine, A World of Science, is online.
Walter Erelen, UNESCO's Assistant Director-General for Natural Sciences, introduces this issue highlighting "Greening the deserts", writing:
(B)elief that we can control our climate has given way to concerns about the human impact on the environment, in particular global warming. Current climate scenarios predict that the driest regions of the world will become even drier.
Only last May, a study published in Science indicated that the tropical climate zone was expanding towards both poles. According to the study, which is based on satellite data from 1979 to 2005, the northern and southern hemispheres’ jet streams – fast-flowing winds about 10 km above the Earth’s surface which mark the limits of the tropics – have each moved about 1° of latitude (about 113 km) nearer the poles. ‘If the jet streams move another 2–3° degrees poleward this century, very dry areas like the Sahara Desert could nudge farther towards the poles, perhaps by a few hundred miles,’ predicts co-author John Wallace of the University of Washington (USA).......
As we shall see in this issue, the past 50 years have shown us that the ecological and socio-economic situation in drylands is not a simple equation governed by factors such as climate, soil, water and vegetation. Market speculation and enormous price fluctuations on commodities like cotton can affect the income of a rural farmer in a remote village in Mali, in the same way that droughts or floods will affect his or her harvest.......
One thing we have learnt over the past 50 years is that, if drylands do not cover the globe, they are nevertheless a global problem. To cite the authors of The Future of Drylands Revisited, ‘dust from central Asia causes health concerns not only in China and Japan but also in North America [and] dust from Africa may be contributing to the decline of coral reefs in the Caribbean.’