摘要
近年来,随着全球气候变暖和人类社会经济活动的增强,处于季节冻土向片状连续多年冻土过渡区的青海高原中、东部多年冻土退化显著.巴颜喀拉山南坡清水河地区岛状冻土分布南界向北萎缩5km;清水河、黄河沿、星星海南岸、黑河沿岸、花石峡等岛状冻土和不连续多年冻土出现融化夹层和不衔接多年冻土,有些地区冻土岛和深埋藏多年冻土消失,多年冻土上限下降、季节冻结深度变浅;片状连续多年冻土地温升高、冻土厚度减薄.1991—2010年巴颜喀拉山南北坡不连续多年冻土分布下界分别上升90m和100m,1995—2010年布青山南北坡不连续多年冻土分布下界分别上升80m和50m.造成冻土退化的主要原因为气候变暖,使得地表年均温度由负变正,冻结期缩短,融化期延长,冻/融指数比缩小.伴随着冻土退化,高寒环境也显著退化,地下水位下降,植被覆盖度降低,高寒沼泽湿地和河湖萎缩,土地荒漠化和沙漠化造成了地表覆被条件改变.
The interior and eastern Qinghai Plateau is located on the transition zones of seasonally frozen ground to predominantly continuous permafrost.Remarkable climate warming has been seen since the 1980s in the plateau.With climate warming and increasing human activities,the permafrost has degraded significantly during the past twenty years.It is found that the lower limit of island permafrost has shifted 5 km northwards in Qingshuihe on the south slopes of the Bayan Har Mountains.The lower limit of permafrost rose 90 m in the south and 100 m in the north slopes of the Bayan Har Mountains,respectively,during the period of 1991-2010.The lower limit of permafrost rose 80 m in the south and 50 m in north slopes of the Buqing Mountains,respectively,during the period of 1995-2010.The changes of active layer depth and ground temperature were also significant.The active layer depth decreased with a rate of 3 cm·a-1,and the annual mean temperature at the bottom of the active layer increased with a rate of approximately 0.05 ℃·a in Madoi Station in 1980-2006.Climate warming could result in degradation of permafrost by turning minus temperature into positive temperature on the ground surface,shorten the frost period,extend the thawing period and decrease the freezing/thawing index.The deterioration of cold environments is also discussed in this paper.
出处
《冰川冻土》
CSCD
北大核心
2012年第3期538-546,共9页
Journal of Glaciology and Geocryology
基金
国家自然科学基金创新群体项目"冻土与寒区工程"(41121061)资助
