Air temperature rising trend and its Impact on Glacier Lakes over Dudhkoshi Basin of Eastern Nepal

With reference to Nepal's east Himalayan silver fir tree ring data , Douglas, 2000, founds that over 250 years the average temperature has increased by 0.11°C since 1950, but, the post-1950 temperature is only 0.06°C higher than the mean achieved between 1800 and 1850. According to research that has carried out using temperature data of meteorological stations, warming trends after 1977 ranging from 0.060 to 0.120C/yr in the Nepal middle mountain and Himalayan regions. Our research from Kathmandu's oldest station shows cooling trends from 1921 to 1958 and warming started after 1959. Warming air temperature trend will lead to an intensification of the global hydrological cycle and could have major impacts on glaciers and glacier lakes. Several studies in the Himalayas have found that glaciers in the region have retreated considerably in the last two decades. An inventory carried out by ICIMOD and UNEP/EAP-AP (2000), shows that there are 2,315 glacial lakes out of which 26 potential dangerous glacier lakes are in Nepal. Our research focuses on air temperature warming trend and its effect on glacier lakes over Dudhkoshi Basin of eastern Nepal. Formation of several new glacier lakes and growth in lake area have found between 1967 and 1996. Eleven new glacier lakes have formed and several lakes have found in growing condition between 1967 and 1996. Formation and growth of such glacier lakes is possible due to fast retreat of glaciers due to warming, which could lead to catastrophic outburst floods.

Keywords: Warming air temperature trend; Glacier lakes; Potential dangerous glacier lakes