A quarter of the world's population depends on degrading land

(Wiley-Blackwell) A new study published in the journal Soil Use and Management attempts for the first time to measure the extent and severity of land degradation across the globe and concludes that 24 percent of the land area is degrading — often in very productive areas. Land degradation – the decline in the quality of soil, water and vegetation – is of profound importance but until now there have been no consistent global data by which to assess its extent and severity. For nearly thirty years the world has depended on the Global Assessment of Soil Degradation (GLASOD) based on the subjective judgement of soil scientists who knew the conditions in their countries. GLASOD indicated that 15 per cent of the land area was degraded, but this was a map of perceptions, rather than measurement of land degradation. The new study by Bai et al. measures global land degradation based on a clearly defined and consistent method using remotely sensed imagery. The results are startling. The new assessment indicates that 24 per cent of the land has been degraded over the period 1981-2003 – but there is hardly any overlap with the GLASOD area that recorded the cumulative effects of land degradation up to about 1990. One of the authors, Dr David Dent of ISRIC – World Soil Information explains: "Degradation is primarily driven by land management and catastrophic natural phenomena.” …

A quarter of the world’s population depends on degrading land