政府间气候变化专门委员会（IPCC）第六次评估报告（AR6）第一工作组报告《气候变化2021：自然科学基础》对全球多年冻土变化的观测事实、气候模式中的评估与未来预测以及多年冻土变化的影响等进行了系统归纳和总结。报告指出，在过去30~40年，多年冻土30?m以上的温度普遍升高（高信度）。2007—2016年期间，全球多年冻土温度升高了（0.29±0.12）?℃（中等信度），与不连续多年冻土区的冻土变暖［（0.20±0.10）?℃］相比，连续多年冻土区观测到了更强的变暖［（0.39±0.15）?℃］。活动层厚度在整个泛北极地区都普遍增加（中等信度）。随着全球气候变暖，多年冻土的范围和体积将会缩小（高信度）。全球地表气温每升高1 °C，距地表3?m的多年冻土体积将减少约25%（中等信度）。然而，由于地球系统模型中对与多年冻土相关物理过程的表征不完整，多年冻土的体积缩小可能被低估。报告还指出，多年冻土退化对全球冻土-碳气候反馈、生态系统及基础设施等方面造成了显著影响，在气候模式及风险评估中应予以考虑。

The Intergovernmental Panel on Climate Change （IPCC） Working Group Ⅰ Sixth Assessment Report （AR6）——Climate Change 2021： The Physical Science Basis， systematically summarized the observed facts of global permafrost changes， assessment and future prediction in climate models， and impacts of permafrost changes. The report states that， increases in permafrost temperatures in the upper 30 m have been observed throughout the permafrost regions over the past three to four decades （high confidence）. Permafrost temperature has increased at （0.29±0.12）?°C near the depth of zero annual amplitude of ground temperature between 2007 and 2016 （medium confidence）. Stronger warming has been observed in the continuous permafrost zone ［（0.39±0.15）?°C］ compared to the discontinuous zone ［（0.20±0.10）?°C］. The active layer thickness has increased throughout the pan-Arctic （medium confidence）. Further global warming will lead to near-surface permafrost volume loss （high confidence）. The volume of permafrost in the top 3 m will decrease by about 25% per 1?°C of global surface air temperature change （medium confidence）. However， such decrease may be underestimated due to an incomplete representation of relevant physical processes in earth system models （ESMs）. As the climate warms， permafrost degradation has significant impacts on permafrost carbon feedback to climate， ecosystems and human infrastructure， which needs to be considered in the climate model and risk assessment.