海底多年冻土是冰期—间冰期海平面变化过程中陆地多年冻土被海水淹没而形成的，主 要分布于北极大陆架区域，其分布范围存在很大的不确定性（面积为1.0×106~2.7×106 km2）。作为 地球系统重要的碳库，海底多年冻土储存着大量有机碳和甲烷（CH4）。在全球变暖的背景下，特别 是在北冰洋海水温度升高的背景下，海底多年冻土的快速退化可能导致碳释放风险加剧，进而影 响全球碳循环与气候变化。东西伯利亚海底多年冻土区已经观测到了CH4向大气释放的现象。然 而，关于海底多年冻土退化速率、碳库规模、温室气体释放量及其机制的研究仍较为有限。值得注 意的是，随着北极地区气候快速变暖、北大西洋暖流的北向扩张和增强引发的北冰洋大西洋化的 进程加剧，以及人类活动的持续增加，使得北极海底冻土CH4加速排放造成的气候风险加大，对未 来人类可持续发展的影响将愈发显著。基于此，系统总结了北极海底多年冻土的空间分布特征、 退化速率及其碳储量，综述了定点、航测和遥感卫星等方法在海底多年冻土区CH4监测与排放特征 研究中的应用，探讨了CH4排放的影响因素，强调了北极海底冻土变化特征及其碳循环研究对全球 气候变化的重要意义。同时，提出了未来研究应结合多种监测方法、加强国际合作、构建综合监测 体系，并充分考虑陆地与海洋因素的协同作用，以此深化对北极海底多年冻土区碳循环及其气候 效应的理解。

Abstract： Subsea permafrost, formed by the inundation of terrestrial permafrost due to the sea-level variations during the glacial-interglacial cycles, is mainly distributed across the Arctic continental shelf. However, there is a large uncertainty in its distribution extent (approximately 1~2.7 million square kilometers). Subsea permafrost is considered a significant carbon reservoir in the Earth system, which stores vast amounts of organic carbon (OC) and methane (CH₄) gas. With global warming and rising temperatures of Arctic Ocean waters, subsea permafrost is undergoing rapid degradation, which may exacerbate carbon release risks. Consequently, the subsea permafrost plays a significant role in influencing the global carbon cycle and climate change. The large CH4 emissions into the atmosphere have been observed in the East Siberian subsea permafrost region. However, the rates of subsea permafrost degradation, the magnitude of carbon reservoirs and gas release are still not clear. In particular, due to the rapid Arctic warming, the northward expansion and intensification of the North Atlantic Current which exacerbates the Atlantification of the Arctic Ocean, and dramatic increases in human disturbance, the climate risk would increase by the accelerated emission of CH4 from Arctic subsea permafrost. These variations will influence the human sustainability in the future. This paper systematically summarizes the spatial distribution, degradation rates, and carbon storage in Arctic subsea permafrost. The applications of methods for CH₄ monitoring in the subsea permafrost were reviewed, including the fixed-point observations, aerial surveys, and remote sensing. Furthermore, this paper discusses factors influencing CH₄ emissions, highlights the importance of studying the characteristics of Arctic subsea permafrost and its carbon cycle for global climate change, and identifies current challenges and suggests future research directions.