气候变化情景下青藏高原多年冻土活动层厚度变化预测

在人类活动和气候变暖的共同影响下,浅层多年冻土近地表和活动层的热状况会发生显著的变化,从而对生态环境、水文、工程等产生较大的影响.以A1B,A2,B1气候变化情景模式为基础,运用Stefan公式计算和预测了青藏高原多年冻土区活动层厚度的变化特征.结果表明:以羌塘盆地为中心,青藏高原多年冻土活动层厚度向其四周不断增加,多年冻土活动层厚度随着气温升高而增加.A1B、A2模式下活动层厚度变化大,相对人类活动强度较小的B1模式活动层厚度变化较小.到2050年时,A1B情景活动层厚度平均约为3.07m,相对于2010年活动层厚度约增加0.3～0.8m;B1情景活动层厚度增加0.2～0.5m;A2情景增加0.2～0.55m.到2099年,A1B情景活动层的平均厚度将约为3.42m;A2情景将可达3.53m;B1情景将可达2.93m.气候变暖将可能加深活动层,百年后将大范围改变多年冻土的空间分布.

Predicting Changes of Active Layer Thickness on the Qinghai-Tibet Plateau as Climate Warming

Thermal conditions of shallow permafrost and in the active layer will change significantly under the combined influence of human activities and climate warming.The change will inevitably impact ecological,hydrological and engineering environments.Adopting changes in the mean annual air temperature under the climate change Scenarios A1B,A2 and B1 as the baseline,the changes of the active layer thickness are predicted by the Stefan’s Equation for the permafrost regions on the Tibetan Plateau in Southwest China.It is found that the active layer depth will increase radically outwards from the Qiangtang basin in the interior of the Tibetan Plateau with rising air temperature under the projected climate scenarios.Changes in the active layer thickness under scenarios A1B and A2 will be more significant than that under scenario B1,because of lesser anthropogenic impacts.In 2050,the mean active layer thickness will reach 3.07 m under Scenario A1B,about 0.3~0.8 m more than that in 2010.At the same time,the increment will be 0.2~0.5 m under Scenario B1 and 0.2~0.55 m under scenario A2.In 2099,the mean active layer thickness will reach 3.42 m under scenario A1B,and 3.53 m under scenario A2.2.93 m under scenario B1.Climate warming will significantly deepen the active layer.One hundred years later,the spatial distribution of permafrost will change largely.