The analysis of the long-term hydrological, meteorological and glaciological data from the Nepal Himalayas has revealed that the climate in the Nepal Himalayas is changing faster than the global average. Moreover, the changes in the high-altitudes have been found more pronounced than in the low-altitudes. For example, annual temperatures at the Rampur station at an altitude of 286 m were increasing at a rate of 0.04°C yr-1 while those at Kathmandu (1136 m), Daman (2314 m) and Langtang (3920 m) were increasing by 0.05, 0.07 and 0.27 ºC yr-1 respectively. Though no definite trends could be found in the annual precipitation records, clear decreasing trends could be seen in the annual number of rainy days during the study period of 1971-2000. The physical and socio-economic impacts of climate change with reference to water resources were also assessed. Sensitivity analyses of river runoff, total water availability, glacier extent and evapotranspiration to a temperature rise were also carried out. The analysis has revealed that the glaciers in the Nepal Himalayas are shrinking rapidly and that there will be no glaciers left by 2180, if the current glacier melting rate continues. Most of the small glaciers will disappear within 3-4 decades. There will be only 11% of the present glacier-ice reserve in the Nepal Himalayas left by 2100, even if the present temperatures do not rise. Previous research and present findings have shown a clear warming trend in the Nepal Himalayas, which will cause an accelerated glacier melt. The accelerated glacier melt will increase the water availability at the beginning but ultimately will reduce it after the glaciers disappear. For example, at a warming rate of 0.06°C yr-1, Nepal’s total water availability may increase up to 178.4 km3yr-1 in 2030 from the present 176.1 km3yr-1 and then will drop down to 128.4 km3yr-1 in 2100. Warming would increase the water requirement on the one hand and decrease the water supply on the other. This will widen the gap between water supply and demand. Changing climate may further exacerbate the water stress, which is already evident in Nepal due to the monsoon-dominated climate. Almost every year in Nepal, there is a usual problem floods and landslides during the rainy seasons because of too much water, whereas there is a common problem of droughts during the dry seasons because of too little water. Climate change would further increase this seasonal imbalance of water in Nepal. Similarly, there will be substantial socioeconomic implications of reduced water availability. The hydropower potential and agricultural production of Nepal would be seriously affected. A reduction in agricultural production would have significant impact on the food security and livelihoods of the subsistence farmers, who make up the majority of the Nepal’s population. Nepal’s current income and food distribution is very uneven. For example, the poorest 20% of the population of Nepal currently consume 6.2% of the total available food, while the richest 20% consume 53.3% of the total food. Currently, per capita daily calorie consumption of the poorest 20% of the population is less than 40% of the minimum calorie requirement for carrying out normal physical activities. Any further reduction in agricultural production may have substantial negative impacts on the food security for these poorest people.
