Climate change and its impacts on glaciers and glacial lakes in Nepal Himalayas

Nepal, a Himalayan country, is often chosen by global scientists to study climate change and its impact on the Himalayan environment. The changes in temperature, precipitation, glaciers, and glacial lakes over Nepal are comprehensively reviewed based on published literature and compared with regional studies. Furthermore, the published glacier datasets were used to calculate and analyze the changes in area, equilibrium line of altitude (ELA) and ice reserves to show the response of glaciers to climate change. We find that the warming trend (0.02 to 0.16 degrees C yr-1) is being more pronounced over Nepal, and heterogeneous changes in precipitation amount, pattern, and frequency are observed with no significant trend. Concurrently, the glaciers are found to be responding with heterogeneous shrinkage in area (- 1 to - 5 km(2) yr(-1)), possessing negative mass balance (- 0.3 to - 0.8 m w.e. yr(-1)), decrease in ice volume (- 4.29 km(3) yr(-1)) and upward shift of the ELA (similar to 20.66 m decade(-1)). The total decrease in ice reserve (- 128.84 km(3)) of Nepal has resulted in similar to 0.32 mm of sea level rise in past 30 years. Moreover, the formation and surface area expansion (0.83 % yr(-1)) of glacial lakes over Nepal have been accelerated. Additionally, we note that Nepal is highly susceptible to glacial lake outburst flood (GLOF) events and document a total of 45 reliable reported and unreported historical GLOF events from 39 glacial lakes across Nepal. This review will facilitate a comprehensive understanding of the current state of climate change and the identification of existing knowledge gaps in Nepal.