Millennium Ecosystem Assessment (see earlier posts Biodiversity Synthesis and 1 and 2.) has released Ecosystems and Human Well-Being: Desertification Synthesis which is freely downloadable from the internet (as a 3 Mb pdf).
My summary of the report is drylands cover about 40% of Earth’s land surface. These areas contain about 2 billion people (~1/3 of world), but only 8% of the world’s supply of water.
Compared to people living in other ecological regions, people living in drylands have the lowest levels of human well-being, including the lowest per capita GDP and the highest Infant Mortality Rate.
Between 1/10th and 1/5th of drylands are degraded – their croplands, pastures and woodlands have been ecologically simplified reducing their economic productivity. The primary causes are over-cultivation, over-grazing, deforestation, and poor irrigation practices
There is substantial variation in rainfall in drylands. Climate change is expected to worsen this variation. People in these regions are already vulnerability of climate variation, climate change and population growth are expected to further decrease the ability of people to maintain their well-being in the face of social and environmental change. However, there are many possible institutional, economic, and ecological responses the people, businesses, and governments can adopt to reduce this vulnerability. In particular, approaches that integrate land and water management are needed.
Figure shows competing Social-Ecological Feedback Loops in Drylands (from MA Desertification Synthesis).