Abstract:

The cryosphere is an integral element of high mountain regions, which are home to roughly 10% of the global population. In recent decades, widespread cryosphere changes affect physical and human systems in the mountains and surrounding lowlands, with impacts evident even in the ocean. The IPCC special report on the ocean and cryosphere in a changing climate (SROCC) was launched on 25 September 2019. The SROCC assesses new evidence on observed recent and projected changes in the mountain cryosphere as well as associated impacts and adaption measures related to natural and human systems. The SROCC reports a dramatic air temperature increase in the high mountains during the last decades, which has led to a significant shrinkage of the mountain cryosphere. Observations show snow cover duration, snow depth and extent have declined, especially in the low elevations. Glacier mass balances are likely most negative in most mountain areas. Regionally averaged mass budgets are likely most negative in the southern Andes, Caucasus and central Europe, and least negative in High Mountain Asia. Observation suggests an increase in permafrost temperature and a decrease in permafrost thickness as well as loss of ice in the ground. The trends in durations of lake and river ice also shorten. Snow cover, glaciers and permafrost are projected to continue to decline in almost all regions throughout the 21st century due to persistent warming. Cryospheric changes have or will alter the frequency, magnitude and location of most related natural hazards, and have important impacts on hydrology, ecosystems and socio-economic systems in high mountain areas. The SROCC also points out that the integrated management approaches, effective governance, international cooperation and treaties can be effective at mitigating impacts from changes in the cryosphere and reducing disaster risk, then to promote adaption and sustainable development in high mountain areas.

Key words: Mountain cryosphere, SROCC, Changes, Impacts, Adaption measures