CMIP6模式对青藏高原多年冻土变化的分析预估

Analysis and Prediction of Permafrost Changes in Qinghai-Xizang Plateau by CMIP6 Climate Models

利用国际耦合模式比较计划第六阶段(CMIP6)多模式的模拟结果,对比观测和青藏高原冻土图评估各模式对当前(1985-2014年)青藏高原与冻土相关气候变量以及多年冻土的模拟能力,并应用多模式集合平均的方法预估了未来4个SSP情景下2021-2040年、2041-2060年、2081-2100年高原多年冻土的变化趋势。结果表明:CMIP6各模式都能够较好地模拟出与冻土相关气候变量的分布特征与趋势,但对于气温的模拟有着较为明显的冷偏差,对于积雪的模拟明显偏大;利用冻结数模型(SFI)计算的当前多年冻土分布与青藏高原冻土图有较好的吻合,1985-2014年的表面多年冻土面积约为134.52×10^(4)km^(2)(包含湖泊和冰川面积);随着气温的升高,21世纪青藏高原多年冻土呈现区域退化的趋势,在SSP1-2.6、SSP2-4.5、SSP3-7.0和SSP5-8.5情景下,青藏高原东部、南部以及北部边缘地区多年冻土呈现区域性退化,至2041-2060年间多年冻土面积分别减少13.81×10^(4) km^(2)、19.51×10^(4) km^(2)、18.02×10^(4)km 2和24.84×10^(4)km^(2),到21世纪末期高原多年冻土出现大规模严重的退化,仅存当前多年冻土面积的69.3%、52.5%、34.4%、26.3%。

The model outputs from the sixth phase of the International Coupled Model Intercomparison Project(CMIP6)are used to diagnose the near-surface permafrost on the Qinghai-Xizang Plateau in this study.The mod‐els'ability to simulate climate variables related to permafrost and permafrost for the current period(1985-2014)was assessed in comparison with observations and permafrost maps of the Qinghai-Xizang Plateau,and the multi-model ensemble averaging method was applied to predict the future trends of near-surface permafrost on the Plateau under four SSP scenarios for the periods 2021-2040,2041-2060 and 2081-2100.The results show that all CMIP6 models can simulate the distribution characteristics and trends of climate variables related to permafrost well,but,the simulation of air temperature has more obvious cold bias,and the simulation of snow is significantly larger.The current permafrost distribution calculated using the surface frost index(SFI)is in good agreement with the permafrost map of the Qinghai-Xizang Plateau,and the surface permafrost area from 1985 to 2014 is about 134.52×10^(4)km^(2)(including the area of lakes and glaciers).With increasing temperatures,the permafrost on the Tibetan Plateau shows a regional degradation trend in the 21st century.Under the SSP1-2.6,SSP2-4.5,SSP3-7.0,and SSP5-8.5 scenarios,permafrost in the eastern,southern and northern margins of the Qinghai-Xizang Plateau showed regional degradation.Between 2041 to 2060,the permafrost area decreases by 13.81×10^(4)km 2,19.51×10^(4)km^(2),18.02×10^(4)km^(2),and 24.84×10^(4)km^(2),respectively,and by the end of the 21st century,the plateau permafrost is severely degraded on a large scale,with only 69.3%,52.5%,34.4%,and 26.3%of the current permafrost area remaining.