Agriculture Reference
In-Depth Information
19.9.3 GLACIAL RETREAT
Himalayan glaciers are receding faster today than the world average (Dy-
urgerov and Meier, 2005) (Fig. 19.2). In the last half of the twentieth cen-
tury, 82% of the glaciers in western China have retreated (Liu et al., 2006).
On the Tibetan Plateau, the glacial area has decreased by 4.5% over the
last 20 years and by 7% over the last 40 years indicating an increased re-
treat rate (Ren et al., 2003). Glacier retreat in the Himalayas results from
“Precipitation decrease in combination with temperature increase. The
glacier shrinkage will speed up if the climatic warming and drying contin-
ues” (Ren et al., 2003).
FIGURE 19.2
Rapid retreat of greater Himalayan glaciers in comparison to the global
average (Dyurgerov and Meier, 2005).
The IPCC Fourth Assessment Report (IPCC, 2007a, 2007b) states that
there is a high measure of confidence that in the coming decades many
glaciers in the region will retreat, while smaller glaciers may disappear al-
together. Various attempts to model changes in the ice cover and discharge
of glacial melt have been made by assuming different climate change sce-
narios. One concludes that with a 2ºC increase by 2050, 35% of the pres-
ent glaciers will disappear and runoff will increase, peaking between 2030
and 2050 (Qin, 2002).
