长江源区冰川对气候变化的响应

Response of Glaciers to Climate Change in the Source Region of the Yangtze River

长江源区是青藏高原冰川分布集中的地区之一, 冰川总面积达1 276.02 km2. 研究表明, 该区属于青藏高原升温幅度最大的地区之一, 到2050年气温将比1961-1990年平均气温高出2.3～2.7 ℃, 降水增加1%～33%. 基于冰川编目资料, 采用有关对长江源区未来50 a内的气温和降水预测数据, 应用冰川系统对气候响应的模型, 对该区未来50 a内冰川变化趋势进行预测. 结果表明: 到2010年、 2030年、 2050年该区冰川面积平均将减少3.2%、6.9%和11.6%;冰川径流平均将增加20.4%、26%和28.5%;零平衡线上升值为14 m、 30 m和50 m左右. 最后, 针对气候变化的不确定性, 对预测结果的不确定性进行了探讨.

The source regions of the Yangtze River is one of the areas in Tibetan Plateau where the glaciers are concentrated, where there is 1276.02 km^2 of glacier area. It is found that air temperature as a whole has a rising trend of 0.2 K· （10a）^-1. The source Regions of the Yangtze River is one of the unusual warming areas on the Tibetan Plateau. On the basis of the structure of the glacier system and the nature of the equilibrium line altitudes at the steady state （ELA0）, functional models of the variation of glacier system are established, using Kotlyakov--krenkes＇s equation, which relates the annual ablation of glacier to the mean summer temperature. The models are applied to the study of the response of glacial runoff to climatic change. The effect of both decreasing air temperature due to rising of ELAo and reduction of glacial area and precipitation rising rate due to climate warming are considered in these models simultaneously. Under the climatic scenarios with temperature rising rate of 0.25 K·（10a）^-1～0. 35 K· （10a）^-1 and precipitation rising rate of 22. 9 mm· K^-1 resulting from HADCM2 model, the modeling results indicate that, by the year of 2010, 2030 and 2050 this century, glacier area will reduce by 3.20％, 6.90％ and 11.6％, respectively; Glacial discharge--runoff increasing rate will be 20. 4％, 26％ and 28.5％, respectively; The ELA0 will rise by about 14 m, 30 m and 50 m in the source regions of the Yangtze River. In the end, this paper discussed the possible variation of glaciers when the climatic change prediction has some uncertainties.