从第三极到北极： 气候与冰冻圈变化及其影响

第三极和北极地区对于区域和全球环境、 社会经济以及国家战略的重要性日益凸现。通过对第三极和北极气候与冰冻圈研究的现状、 趋势进行梳理总结， 为未来的系统研究提供借鉴。结果显示， 第三极和北极气候系统与冰冻圈正在发生显著变化并预计将持续下去。第三极和北极地区气温在以全球平均升温速度两倍的速率变暖， 且在20世纪70年代以来， 变化总体趋势高度一致； 降水变化总体呈增加趋势， 但变率和不确定性较大； 极端事件（尤其是极端降水）的频率增加； 积雪范围总体上呈现减少趋势， 雪水当量、 积雪天数的变化存在区域和周期性差异； 多年冻土温度升高， 活动层厚度增加， 亦呈现较大的区域差异。这些变化不仅对生态、 水文、 碳循环产生重要影响， 而且对基础设施、 社会经济以及人类健康产生不可忽视的影响， 包括重金属污染、 食品安全等。气候及冰冻圈快速变化会通过反照率反馈、 水汽反馈等机制被放大， 并通过一系列大气及海洋环流过程， 对周边乃至全球气候系统产生广泛影响。目前第三极和北极研究中面临的重要共同问题包括极度稀疏的地面观测资料、 模型物理机制和精细化描述不足以及缺少与周边地区乃至全球系统关联的量化研究和可靠证据。这些问题的解决都需要依赖地面监测网络的扩展以及对冰冻圈和气候系统物理过程理解的提升。从第三极到北极， 不仅是研究视角的扩大， 更是全面理解第三极和北极在地球系统中作用的必经之路。

From the Third Pole to the Arctic： changes and impacts of the climate and cryosphere

The Third Pole and Arctic are important for environmental， social-economic， and political developments and strategies for China. It is expected to provide some experiences for the future comprehensive research by summarizing the current situation and tendency of the researches on the Third Pole and Arctic. The Third Pole and Arctic climate and cryosphere components showed significant changes， which are expected to continue in the future decades. Land air temperature in the Third Pole and Arctic warmed at twice the rate of global warming and the overall trends were highly consistent since the 1970s. The frequency of extreme events increased over the past decades. Seasonal snow cover， permafrost， land ice， sea ice， ecosystem， and hydrological cycles also showed considerable changes. These changes have not only important impacts on ecology， hydrology， and carbon cycles but also considerable impacts on infrastructure， socioeconomics， and human health. Continuously significant changes in the climate system and cryosphere may affect the globe through the amplification derived from albedo and water vapor feedbacks and a series of atmospheric circulation processes and ocean circulation processes. Currently， the common challenges of studies in the Third Pole and Arctic include extremely sparse ground monitoring networks， insufficient physics and spatiotemporal resolutions in models， and the lack of quantitative research and reliable evidence in the teleconnections within global systems. Resolving these issues mainly depends on the expansion of the ground monitoring networks and the improvements of understanding of the physics in the cryosphere and climate system. Extending from the Third Pole to the Arctic is not only the expansion of the research perspective but also important to understand their roles in the Earth system.