多年冻土是寒冷气候的产物，气候变暖则会造成多年冻土退化。多年冻土退化的表征之一就是地下冰融化，使得地表 土壤失去支撑，从而形成滑塌、沉降等热喀斯特地貌。热喀斯特地貌不仅会影响到工程建筑，还会破坏地表植被，导致生 态系统退化。热融沉降形成的低洼地还会积水并逐步发展为热融湖塘。热喀斯特地貌除了直接改变地表景观外，还会改变 土壤的水文和碳氮循环的过程。目前热喀斯特地貌的发展及其影响在多年冻土环境研究中已引起了广泛关注，定量评估热 喀斯特地貌对碳循环的影响也是评估多年冻土区对全球变化的响应及气候反馈效应的重要环节。

Permafrost, a product of cold climate, can be degraded by climate warming. Permafrost thaws lead to the melting of ground ice and the water subsequent drain away, this process removes the support of surface layer, and thus leads to thermokarst terrains including thaw slump, ground subsidence. Thermokarst terrains not only affect infrastructure engineering, they can also deteriorate vegetation growth and deteriorate ecosystem. The ground subsidence can further gradually form thermokarst lake. Thermokarst terrains directly change landforms, and they also have great effects on hydrology, as well as carbon and nitrogen cycle. The topic of thermokarst development and its impacts have created many concerns in the permafrost environmental science. The quantitative assessment of effects of thermokarst terrains on carbon cycle is a fundamental step towards to understanding the response of permafrost and its feedback to climate change.