近日，德国赫姆霍兹极地研究所Niu, Lu小组取得一项新突破。他们发现夏季降雪是导致末次盛冰期Laurentide冰盖迅速增长的原因。该项研究成果发表在2024年4月12日出版的《自然—地球科学》上。
研究人员建立了一个具有相互作用冰盖的地球系统模型，以表明由于大气环流和冰盖几何形状之间的反馈，38,000年前独特的初始北美(Laurentide)冰盖与末次冰盛期趋同于一致的构型。值得注意的是，研究设计的模型中，冰推进的速度和空间格局受夏季降雪量的控制，而夏季降雪量取决于与冰盖几何形状相关的北大西洋暖池的水分输送路径。
夏季降雪量的增加对冰盖表面物质平衡的影响，不仅直接增加了积累量，还通过雪/冰反照率反馈间接减少融化量。这些反馈为一系列初始冰盖状态的冰增长提供了有效的机制，并可能解释北美冰量在末次冰河期的快速增长，并可能推动前冰河期的增长。
据悉，学者对地球系统末次冰期对天文作用力的非线性响应已经进行了广泛的研究。然而，在21,000年前的末次盛冰期，最大程度的冰盖扩张的速度和空间几何形状仍然不确定。
附：英文原文
Title: Rapid Laurentide Ice Sheet growth preceding the Last Glacial Maximum due to summer snowfall
Author: Niu, Lu, Knorr, Gregor, Krebs-Kanzow, Uta, Gierz, Paul, Lohmann, Gerrit
Issue&Volume: 2024-04-12
Abstract: There has been extensive research into the nonlinear responses of the Earth system to astronomical forcing during the last glacial cycle. However, the speed and spatial geometry of ice sheet expansion to its largest extent at the Last Glacial Maximum 21 thousand years ago remains uncertain. Here we use an Earth system model with interactive ice sheets to show that distinct initial North American (Laurentide) ice sheets at 38 thousand years ago converge towards a configuration consistent with the Last Glacial Maximum due to feedbacks between atmospheric circulation and ice sheet geometry. Notably, ice advance speed and spatial pattern in our model are controlled by the amount of summer snowfall, which is dependent on moisture transport pathways from the North Atlantic warm pool linked to ice sheet geometry. The consequence of increased summer snowfall on the surface mass balance of the ice sheet is not only the direct increase in accumulation but the indirect reduction in melt through the snow/ice–albedo feedback. These feedbacks provide an effective mechanism for ice growth for a range of initial ice sheet states and may explain the rapid North American ice volume increase during the last ice age and potentially driving growth during previous glacial periods.
DOI: 10.1038/s41561-024-01419-z
Source: https://www.nature.com/articles/s41561-024-01419-z