TABLE 2.1 Glacial Area Estimates from Different Studiesa

Region Glacier Area (km2) Data Source
HKH 114,800 WGMS (2008)
    116,180 Xu, J., et al. (2009)
    60,000 ICIMOD (2011b)
    99,261 Yao et al. (2012)
Central HKH 33,050 WGMS (2008)
    32,182 ICIMOD: Eriksson et al. (2009)
    71,182 Indian Space Agency: ISRO (2011)
Himalayas 33,050 Dyurgerov and Meier (1997, 2005)
Karakoram 15,400 Dyurgerov and Meier (1997)
    16,000 Dyurgerov and Meier (2005)
    16,600 Yao et al. (2012)
Indus Basin 32,246 ISRO (2011)
    36,431 Raina (2009)
    21,192 ICIMOD (2011b)
Ganges Basin 18,392 ISRO (2011)
    9,012 ICIMOD (2011b)
Brahmaputra Basin 20,542 ISRO (2011)
    14,020 ICIMOD (2011b)
China 59,406 Chinese Academy of Sciences: Liu, et al. (2000)
India 37,959 Geological Survey of India in ICIMOD (2011b)
Nepa l4,212 ISRO (2011)
aComparisons of glacial area among different studies are difficult because spatial extents are often different or not well categorized.

evidence that glaciers are more stable in the western Himalayas. This is because glacial retreat is sensitive to more factors than simply elevation, including precipitation regime, local temperatures, and debris cover.

Rates of glacial retreat in the HKH are not well understood because of a lack of field data (Kargel et al., 2011; Thompson, 2010), making it difficult to understand regional climate change impacts (Scherler et al., 2011b). One of the most studied glaciers in the region, AX010 in Nepal, has consistently been shown to have a negative mass balance. If the climate conditions remain consistent with the period 1992 to 1996, AX010 has been predicted to disappear by the year 2060 (Kadota, 1997). However, this glacier is relatively small, with an area of only 0.38 km2, and exists at a low altitude, extending to only 5,300 m, and thus only represents small, low-elevation glaciers (Fujita and Nuimura, 2011). However, approximately 50 percent of the area of Nepal glaciers is at altitudes above approximately 5,400 m (Alford et al., 2010; Bajracharya et al., 2011). Therefore, glacier AX010 is not a good indicator of general trends in the HKH region. In a study of glaciers in northern India, Kulkarni et al. (2011) found that glaciers smaller than 1 km2 lost an average of 28 percent of their area between 1962 and 2001, while glaciers greater than 10 km2 lost an average of 12 percent of their area in the same time period, further indicating that smaller glaciers cannot be used to determine regional trends.

Extrapolation of these few mass balance studies over the greater High Asian region has been used to estimate a rate of water loss from glacial retreat between 2002 and 2006 of -55 Gt yr-1 for this entire region, with -29 Gt yr-1 over the eastern Himalayas alone (Dyurgerov, 2010). In contrast, Jacob et al. (2012) used new information from the Gravity Recovery and

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