March 2009 - 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% 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.
That quarter of the world's population just happens to be growing faster than the rest of the world's population. These degrading areas are therefore going to get worse and bigger.
Overall, a quarter of the world's population depends directly on these degrading areas.
Southern Africa, South East Asia and South China are worst hit.
The worst-hit areas are Africa south of the Equator, SE Asia and S China. The worst-affected countries, with more than 50 per cent of territory degrading are, in Africa, the Congo, Zaire, Equatorial Guinea, Gabon, Sierra Leone, Zambia and the most affected (95 per cent degrading) Swaziland; in Asia, Myanmar, Malaysia, Thailand, Laos, Korea and Indonesia. In terms of the rural population affected, the greatest numbers are in China, with nearly half a billion, India, Indonesia, Bangladesh and Brazil. The usual suspects, such as the African Sahel and around the Mediterranean are much less affected."
Check out this distorted global map representation of where the human population will be concentrated in 2050. If you want to see wild animals in Africa better not wait till you are retired.
World Bank demographer John May says Africa's population will double in 28 years.
The sub-Saharan population is growing at the rate of 2.5 percent per year as compared to 1.2 percent in Latin America and Asia. At that rate, Africa's population would double in 28 years. The reason for the fast population increase in Africa is the rapid decline in infant and child mortality, whilst fertility levels have remained high and are decreasing only slowly.
Today, African women bear 5.5 children on average during their lifetime, except in Southern Africa. The key issue is the lag between the infant and child mortality decline, on the one hand, and the fertility decline, on the other. The AIDS epidemic, despite all the development problems it brings to Africa, will not fundamentally change the demographic equation.
|Share |||Randall Parker, 2009 March 22 02:19 PM Trends Habitat Loss|