Since industrialization, human activities have significantly altered the atmospheric composition, leading to climate change of an unprecedented character. The global mean temperature is expected to increase between 1.4 to 5.8ºC over the next hundred years. The consequences of this change in global climate are already being witnessed in the Himalayan glaciers and glacial lakes. The Himalayan glaciers are retreating at rates ranging from 10 to 60 metres per year and many small glaciers (<0.2 sq km) have already disappeared. Vertical shift of glaciers as great as 100m have been recorded during the last fifty years. With the result of retreating glaciers, the lakes are growing in number and size as well in the Himalaya. A remarkable example is Lake Imja Tsho in the Everest region; while this lake was virtually nonexistent in 1960, now it covers nearly 1 sq km in area. Similar observations were made in the Pho Chu basin of the Bhutan Himalaya, where the change in size of some glacial lakes has been as high as 800 per cent over the past 40 years. At present, several supraglacial ponds on the Thorthormi glacier are growing rapidly and consequently merging to form a larger lake. These lakes pose a threat of glacial lake outburst flood (GLOF), and GLOFs are often catastrophic on life and property of the mountain people living downstream. At least thirty-two GLOF events recorded in Himalaya that resulted in heavy loss of human lives and their property, destruction of infrastructure besides damages to agriculture land and forests. The global warming in the coming decades will amplify the GLOF events with the accelerating retreat of glaciers and formation of many potentially dangerous glacial lakes. Monitoring of glaciers and glacial lakes are utmost important to understand the status of the lake and need to prioritized for the installation of early warning systems and mitigation measures before planning the mountain infrastructure for the sustainable development. Regional cooperation is also required for knowledge management on GLOF issues due to trans-boundary nature of GLOF henomena.
