基于未来温室气体中等排放情景下气候模式给出的气候预测结果的高分辨率降尺度分析结果,运用两种方法(年均温法和高程模型法)模拟了1980--1999,2030-2049和2080--2099年3个时段青藏高原多年冻土分布。结果表明,以年均地温一1℃作为多年冻土划分依据的年均温法模拟的目前(1980--1999年)高原多年冻土面积为127.99万km^2,与世界数据中心给出的青藏高原现代多年冻土面积为129.12万km^2的估算接近(误差率仅为0.86%);到本世纪中期(2030--2049年),高原多年冻土面积减少为87.26万km^2,退化率达到31.82%;而到本世纪末(2080--2099年),高原多年冻土面积只有69.25万km^2,较目前将退化45.89%。不同高度带的对比分析还发现,与高原及其邻近地区年均气温的升高一般随海拔高度而增加的趋势相反,未来高原多年冻土的退化率将随着海拔高度增加而降低。在全球变暖过程中的冻土退化,特别是高原东南部冻土向西北部的逐步退缩,对高原冻土区工程稳定性的影响应引起我们的足够重视。
Based on the high-resolution downscaling data produced with a climate model under a mid-range emission scenario of greenhouse gases (A1B), two methods (annual-mean ground temperature method and the elevation model method) have been used to analyze permafrost distribution on the Qinghai-Tibet plateau for three periods 1980 - 1999, 2030 -2049 and 2080 -2099. Taking - 1 ℃ of annual-mean ground temperature as the boundary of permafrost in the first method, we can determine present-day permafrost distribution with an area of 1279900 km2, which is close to the observational result given by the World Data Center (WDC). In comparison with the situation at the end of the twentieth century, the area of permafrost on the plateau will reduce by 31.82% and 45.89% by the middle and the end of this century, being 872600km^2 and 692500km^2, respectively. Comparative analyses of different elevation zones show that the degradation rate of permafrost decreases with the elevation, while the warming amplitude of surface air temperature increases with the elevation in the Qinghai-Tibet Plateau and the surroundings. Impacts of permafrost degradation induced by global warming on environments such as engineering stability in Qinghai-Tibet Plateau should draw our sufficient attention.