30 July 2008 |
The Tibetan plateau
Climate change is affecting the Tibetan plateau, threatening regional water supplies and altering atmospheric circulation for half the planet.
The plateau is the world's third largest store of ice. But its temperature has risen by up to 0.3 degrees Celsius every ten years over the last fifty years — approximately three times the global warming rate.
As a result, 82 per cent of the plateau's glaciers have retreated while ten per cent of its permafrost has degraded.
Among the causes is dust blowing from regional deserts during summertime, which changes radiation levels reaching the plateau by both reflecting and absorbing sunlight.
Black carbon emissions, caused by burning biomass, are also causing the plateau's melting season to start early and last longer.
The changes could have major effects. Glacial lakes increase the risk of floods, the shrinkage of glaciers will affect water supplies in the surrounding area and the loss of permafrost will endanger local ecosystems and render structures of the Qinghai-Tibet railway vulnerable.
And the effects may be felt further afield. Some climate models show that a rise in the plateau's surface temperature over the oceans can alter the intensity of the Indian monsoon, whilst convection over the plateau may also carry pollutants in water vapour globally.