【摘要】 青藏高原从70年代后期气温持续转暖,造成高原多年冻土呈区域性退化状态,已不同程度地影响到40m深以上的地温,特别是20m以上的浅层地温最为明显。近15～20a以来地温对比表明,高原上季节冻土区,河流融区及岛状冻土区内含冰(水)量较小的地段,年平均地温升高0.3～0.5℃,大片连续多年冻土区内上升0.1～0.3℃。另外,考虑高原气候变化趋势及人为因素的影响对未来50a高原多年冻土进行预测。更多还原

【Abstract】 The climate in the Qinghai-Xizang Plateau has been becoming warmer since the late 1970’s. The obvious warmer winter and smaller annual range of air temperature have resulted in a regional permafrost degradation in the pla teau. The evidences which include the decrease of seasonal thawing depth, increase of seasonal freezing depth and the thawed layer are found between the active layer and the underlain permafrost in the regions near the permafrost lower altitudinal limit or near taliks. The ground te mperatures from surface to 40 m depth, especially to 20 m depth, have been affected by the climate warming in various degrees. Comparision of the ground temperature in the past 15-20 years shows that the mean annual ground temperatures rise about 0.3-0.5℃ in the regions of seasonal frozen ground, river taliks and island permafrost regions where ice content of soil is relatively small. In the regions underlain continuously by permafrost, the mean annual ground temperature rises about 0.1-0.3 ℃. According to the research results of climate prediction and taking the man-made factors into consideration, the permafrost changes in the following 50 years are estimated in the paper. Given a 1 ℃ air temperature warming in another 50 years, the mean annual ground temperature in the permafrost region will increase by about 0.4-0.5 ℃ ; the lower limit of permafrost will rise about 150- 200 m; most of the present permafrost of which the thickness is less than 10 m will be melted; the main body of the present island permafrost will disappear, leaving traces of frozen ground lay deeply under the ground surface (of which the upper table will be deeper than 10 m); and the total area of permafrost will diminish dramastically.更多还原