Changes in the global cryosphere and their impacts:A review and new perspective

As one of the five components of Earth's climatic system,the cryosphere has been undergoing rapid shrinking due to global warming.Studies on the formation,evolution,distribution and dynamics of cryospheric components and their interactions with the human system are of increasing importance to society.In recent decades,the mass loss of glaciers,including the Greenland and Antarctic ice sheets,has accelerated.The extent of sea ice and snow cover has been shrinking,and permafrost has been degrading.The main sustainable development goals in cryospheric regions have been impacted.The shrinking of the cryosphere results in sea-level rise,which is currently affecting,or is soon expected to affect,17 coastal megacities and some small island countries.In East Asia,South Asia and North America,climate anomalies are closely related to the extent of Arctic sea ice and snow cover in the Northern Hemisphere.Increasing freshwater melting from the ice sheets and sea ice may be one reason for the slowdown in Atlantic meridional overturning circulation in the Arctic and Southern Oceans.The foundations of ports and infrastructure in the circum-Arctic permafrost regions suffer from the consequences of permafrost degradation.In high plateaus and mountainous regions,the cryosphere's shrinking has led to fluctuations in river runoff,caused water shortages and increased flooding risks in certain areas.These changes in cryospheric components have shown significant heterogeneity at different temporal and spatial scales.Our results suggest that the quantitative evaluation of future changes in the cryosphere still needs to be improved by enhancing existing observations and model simulations.Theoretical and methodological innovations are required to strengthen social economies'resilience to the impact of cryospheric change.