The Greenland ice sheet and greenhouse warming
The Greenland ice sheet and greenhouse warming
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DOI：
10.1016/0031-0182(91)90174-p
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发表时间：
1991-03
期刊：
影响因子：
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通讯作者：
P. Huybrechts;A. Letréguilly;N. Reeh
中科院分区：
文献类型：
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作者：
P. Huybrechts;A. Letréguilly;N. Reeh
冰川和冰盖的加速融化以及海平面的上升通常被认为是预期的地球大气温室变暖的重要方面。本文讨论了格陵兰冰量收支的敏感性，并提出了未来几百年海平面上升的格陵兰分量的初步预估。为此，“菲拉赫II温度情景”被规定，综合质量平衡模型的输出用于驱动冰盖的高分辨率三维热力学模型。质量平衡模式由两部分组成：累积部分是基于目前的观测值，并受平均和温度变化的强迫。消融模型基于度日法，考虑了日和年温度循环，这是冰雪融化和叠加冰形成的不同度日因子。在目前的气候条件下，总质量平衡（以每年冰当量计算）的结果如下：599.3× 109m3的积累，281.7× 109m3的径流（假设平衡预算），317.6× 109m3的冰山崩解。然后计算出1K均匀升温可使径流量增加119.5× 109m3。由于累积量也增加了32× 10 9 m³，这导致总质量平衡减少了887.5× 10 9 m³的冰，相当于海平面上升0.22 mm/年。如果温度升高超过2.7 K，径流量就会超过累积量，如果冰盖动力学保持不变，这将为世界海洋额外增加0.8毫微当量。实施菲拉赫II情景（升温至4.23 K）并及时积累物质平衡变化（静态响应）将导致到公元2100年全球海平面上升7.1厘米，但如果变暖翻倍，这一数字可能高达每世纪40厘米。在随后的涉及冰流的动态模型中，发现冰盖通过在边缘动态地产生更陡峭的斜坡来产生抵消效应，从而减少了径流发生的面积。这种影响在冰盖的东北部特别明显，在较小的温度扰动中也更为明显。然而，所有这些实验无疑都突出了格陵兰冰盖在气候变暖方面的脆弱性。
Increased melting on glaciers and ice sheets and rising sea level are often mentioned as important aspects of the anticipated greenhouse warming of the earth's atmosphere. This paper deals with the sensitivity of Greenland's ice mass budget and presents a tentative projection of the Greenland component of future sea level rise for the next few hundred years. To do this, the ‘Villach II temperature scenario’is prescribed, output from a comprehensive mass balance model is used to drive a high-resolution 3-D thermomechanic model of the ice sheet. The mass balance model consists of two parts: the accumulation part is based on presently observed values and is forced by changes in mean anr tempeerature. The ablation model is based on the degree-day method and accounts for daily and annual temperature cycle, a different degree-day factor for ice and snow melting and superimposed ice formation. Under present-day climatic conditions, the following total mass balance results (in ice equivalent per years): 599.3× 10 9 m 3 of accumulation, 281.7× 10 9 m 3 of runoff assuming a balanced budget, 317.6× 10 9 m 3 of iceberg calving. A 1K uniform warming is then calculated to increase the runoff by 119.5× 10 9 m 3. Since accumulation also increases by 32× 10 9 m 3, this leads to reduction of the total mass balance by 887.5× 10 9 m 3 of ice, corresponding to a sea level rise of 0.22 mm/yr. For temperature increase larger than 2.7 K, runoff, exceeds accumulation, and if ice sheet dynamics were to remain unchanged, this would add an extra amount of 0.8 mmyr to the worl's oceans. Imposing the Villach II scenario (warming up to 4.23 K) and accumulating mass balance changes forward in time (static response) would then result in a global sea level rise of 7.1 cm by 2100 AD, but this figure may go up to as much as 40 cm per century in case the warming is doubled. In a subsequent dynamic model involving the ice flow, the ice sheet is found to produce a counteracting effect by dynamically producing steeper slopes at the margin, thereby reducing the area over which runoff can take place. This effect is particularly apparent in the northeastern part of the ice sheet, and is also more pronounced for the smaller temperature perturbations. Nevertheless, all these experiments certainly highlight the vulnerability of the Greenland ice sheet with respect to a climatic warming.