全球山地冰冻圈变化、影响与适应

冰冻圈是高山地区不可或缺的重要组成部分,居住着全球约10%的人口。近几十年来,冰冻圈变化对山区和周围地区的自然和人类系统产生了广泛而深远的影响,对海洋也发挥着重要作用。IPCC最新发布的《气候变化中的海洋和冰冻圈特别报告》（SROCC）指出,过去几十年全球高山区气温显著升高,使山地冰冻圈发生了大范围显著退缩。观测到的山地（特别是低海拔山区）积雪期缩短、雪深和积雪覆盖范围减小;冰川物质持续亏损,其中全球最大的冰川负物质平衡出现在南安第斯山、高加索山和欧洲中部,亚洲高山区冰川负物质平衡最小;多年冻土温度升高、厚度减薄,地下冰储量减少;河、湖冰持续时间缩短。随着气候持续变暖,山地冰冻圈在21世纪仍将呈继续退缩状态。到21世纪末,低海拔山区积雪深度和积雪期将减少,冰川物质损失继续增加,多年冻土持续退化。冰冻圈变化已经或将改变山地灾害发生频率和强度,并对水资源、生态系统和经济社会系统产生重要影响。应对山地冰冻圈变化应从管理和优化利用冰冻圈资源、加强冰冻圈变化灾害风险的有效治理、增强国际合作及公约制定等适应策略着手开展,增强适应能力,从而有益于推动山地生态系统和经济社会系统可持续发展。

Changes in the mountain cryosphere and their impacts and adaptation measures

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 21 st 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.