McConnell JR, Arthern RJ, Mosley-Thompson E, Davis CH, Bales RC, Thomas R, Burkhart JF, Kyne JD
Desert Research Institute, University & Community College System of Nevada, Reno 89512, USA.
Nature. 2000 Aug 24;406(6798):877-9. doi: 10.1038/35022555.
The response of grounded ice sheets to a changing climate critically influences possible future changes in sea level. Recent satellite surveys over southern Greenland show little overall elevation change at higher elevations, but large spatial variability. Using satellite studies alone, it is not possible to determine the geophysical processes responsible for the observed elevation changes and to decide if recent rates of change exceed the natural variability. Here we derive changes in ice-sheet elevation in southern Greenland, for the years 1978-88, using a physically based model of firn densification and records of annual snow accumulation reconstructed from 12 ice cores at high elevation. Our patterns of accumulation-driven elevation change agree closely with contemporaneous satellite measurements of ice-sheet elevation change, and we therefore attribute the changes observed in 1978-88 to variability in snow accumulation. Similar analyses of longer ice-core records show that in this decade the Greenland ice sheet exhibited typical variability at high elevations, well within the long-term natural variability. Our results indicate that a better understanding of ice-sheet mass changes will require long-term measurements of both surface elevation and snow accumulation.
极地冰盖对气候变化的响应严重影响着未来海平面可能出现的变化。最近对格陵兰岛南部进行的卫星测量显示，高海拔地区总体海拔变化不大，但存在很大的空间变异性。仅依靠卫星研究，无法确定导致观测到的海拔变化的地球物理过程，也无法判定近期的变化速率是否超出了自然变异性的范围。在此，我们利用基于物理原理的雪层压实模型以及从12个高海拔冰芯重建的年积雪记录，得出了1978 - 1988年格陵兰岛南部冰盖海拔的变化情况。我们通过积雪驱动的海拔变化模式与同期冰盖海拔变化的卫星测量结果高度吻合，因此将1978 - 1988年观测到的变化归因于积雪的变异性。对更长冰芯记录进行的类似分析表明，在这十年间，格陵兰冰盖在高海拔地区呈现出典型的变异性，完全处于长期自然变异性的范围内。我们的研究结果表明，要更好地理解冰盖质量变化，需要对地表海拔和积雪进行长期测量。
