Krinner G, Mangerud J, Jakobsson M, Crucifix M, Ritz C, Svendsen J I
LGGE, CNRS-UJF Grenoble, BP 96, F-38402 Saint Martin d'Hères, France.
Nature. 2004 Jan 29;427(6973):429-32. doi: 10.1038/nature02233.
Large proglacial lakes cool regional summer climate because of their large heat capacity, and have been shown to modify precipitation through mesoscale atmospheric feedbacks, as in the case of Lake Agassiz. Several large ice-dammed lakes, with a combined area twice that of the Caspian Sea, were formed in northern Eurasia about 90,000 years ago, during the last glacial period when an ice sheet centred over the Barents and Kara seas blocked the large northbound Russian rivers. Here we present high-resolution simulations with an atmospheric general circulation model that explicitly simulates the surface mass balance of the ice sheet. We show that the main influence of the Eurasian proglacial lakes was a significant reduction of ice sheet melting at the southern margin of the Barents-Kara ice sheet through strong regional summer cooling over large parts of Russia. In our simulations, the summer melt reduction clearly outweighs lake-induced decreases in moisture and hence snowfall, such as has been reported earlier for Lake Agassiz. We conclude that the summer cooling mechanism from proglacial lakes accelerated ice sheet growth and delayed ice sheet decay in Eurasia and probably also in North America.
大型冰前湖因其巨大的热容量而使区域夏季气候变冷，并且已证明它们会通过中尺度大气反馈改变降水，就像阿加西兹湖的情况一样。约9万年前，在上一个冰川期，当以巴伦支海和喀拉海为中心的冰盖阻挡了俄罗斯向北流的大河时，在欧亚大陆北部形成了几个大型冰坝湖，其总面积是里海的两倍。在此，我们使用大气环流模型进行了高分辨率模拟，该模型明确模拟了冰盖的表面质量平衡。我们表明，欧亚冰前湖的主要影响是，通过俄罗斯大部分地区夏季的强烈区域降温，显著减少了巴伦支 - 喀拉冰盖南缘的冰盖融化。在我们的模拟中，夏季融化减少明显超过了湖泊导致的水分减少以及因此造成的降雪减少，就像之前报道的阿加西兹湖那样。我们得出结论，冰前湖的夏季降温机制加速了欧亚大陆以及可能还有北美地区冰盖的增长并延迟了冰盖的消退。
