Thirty-year Records Of Glacier Melting In The Nepal Himalayas

Two net balance records of neighboring glaciers under different conditions are compared to examine temporal variations in glacier melting in the Himalayas. No melt occurred at one site due to its high elevation, whereas a significant melt was observed every year at the other site. The difference between the net balances of the two glaciers is calculated as the _emelt index_Eof glacier-melting conditions. Comparing instrumental meteorological records at a rural station suggests that the calculated melt index is a good proxy of the summer mean air temperature at high elevations, where measured meteorological records are few. The melt index shows a decadal fluctuation with a major amplitude never before seen in previous ice core studies in the Himalayas. Ice cores from melting sites have been considered unreliable in reconstructing past climates since climatic signals in ice are disturbed by meltwater infiltration. However, we suggest a new use of a so-called bad ice core to glean information not obtainable from a good quality ice core alone.