Isolating the Larsen-C Ice Shelf Mass Instability

隔离 Larsen-C 冰架质量不稳定性

• 批准号: NE/E014089/2
• 负责人: Andrew Shepherd
• 金额: $ 31.27万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FE014089%2F2
• 关键词: Isolating; Larsen; Ice; Shelf; Mass

In 1988, the World Meteorological Organisation and the United Nations set up an international panel of expert scientists to collect information about climate change, in response to growing public concerns about issues such as global warming and the hole in Earth's ozone layer. Since then, the panel's major findings have shown that air temperatures and sea levels are rising faster than can be explained through natural changes, and that pollutants from 20th Century industrialisation are a likely factor. Earths' present-day climate changes are closely related to the ice frozen in its polar regions. As air temperatures rise, ice melts and drains into the oceans, causing sea level rise. The costs of this simple relationship could be enormous. There is enough ice frozen in Antarctica to raise global sea levels by 65 m if it were to rapidly melt, a change that would flood 13 of the worlds 20 largest cities including London. Some of the fastest climate changes on Earth have taken place at the Antarctic Peninsula, the warmest sector of Antarctica, due south of Chile and Argentina. Air temperatures measured there since early explorations in the 19th Century, show a warming of more than 5 degrees C during the past 100 years. Perhaps the most dramatic climate changes ever witnessed have occurred during the last decade, when, in 1995 and 2002, giant sections of the floating Larsen Ice Shelf - Larsen-A and /B, each about the size of Cornwall - disintegrated into thousands of icebergs, causing widespread alarm. These events, depicted as a solitary crevasse fracture in the opening scene of last years blockbuster The Day After Tomorrow, were truly catastrophic, and are probably the only natural disaster ever to be understated in a Hollywood movie. More importantly, the collapses have left scientists unsure as to what caused them and how they might affect our future climate. In the wake of each collapse, new embayments have been revealed where the floating Larsen Ice Shelf used to exist, and glaciers inland of these bays have accelerated, calving enough extra ice to raise global sea levels by 0.1 mm each year. Although this amount seems small, scientists are now concerned about the much larger ice field upstream of the remaining Larsen-C section, which contains enough ice to raise global sea levels by over 50 mm. That ice would be seriously at risk if the Larsen-C section were to collapse. We have designed a series of experiments, combining satellites and field exploration, to solve the mystery of Larsen Ice Shelf collapses. Our measurements will identify whether changes in the ocean or the atmosphere were to blame. We will use a sensitive radar system / similar to road speed cameras - to measure extremely slow changes in the ice shelf thickness of about 0.1 mm per hour. We will also drill through the top layers of the ice shelf and extract cores of ice, which, like tree rings, tell us how climate has changed over the past century. When combined with new satellite measurements of ice flow and thinning, our field measurements will allow us to detect whether the ocean beneath the floating Larsen Ice Shelf is warmer than expected, or whether summertime ice melting at the surface is greater than expected. Once the cause of the collapses has been identified, we will build a computer model of the ice shelf to investigate how it might fracture in the future. Our experiments will identify the cause of the catastrophic Larsen Ice Shelf collapses in 1995 and 2002. They will also determine whether the remaining Larsen-C section will become vulnerable in the coming years. And, most important of all, we will predict how fast global sea levels will rise if the Larsen-C collapses at some time in the future.

1988年，世界气象组织和联合国成立了国际专家科学家小组，以收集有关气候变化的信息，以应对公众对全球变暖和地球臭氧层漏洞等问题的关注。从那时起，该小组的主要发现表明，空气温度和海平面的提高速度要比通过自然变化所能解释的要快，而20世纪工业化的污染物可能是一个因素。地球当今的气候变化与在其极区域中冻结的冰密切相关。随着空气温度的升高，冰融化并排入海洋，导致海平面上升。这种简单关系的成本可能是巨大的。如果要快速融化，南极洲有足够的冰块将全球海平面提高65 m，这一变化将淹没世界中20个最大城市，包括伦敦在内。地球上一些最快的气候变化发生在南极半岛，南极最温暖的地区，智利和阿根廷南部。自19世纪早期探索以来，在那里测得的空气温度显示出过去100年的5度以上C的变暖。在过去的十年中，有史以来最引人注目的气候变化也许发生了，当时1995年和2002年，浮动的Larsen Ice架（Larsen -a和 /b）的巨大部分大约是康沃尔（Cornwall）的大小 - 崩解成成千上万的冰山，引起了广泛的警报。这些事件被描述为在去年后一天的大片开幕场景中被描述为一个孤独的裂缝，确实是灾难性的，可能是好莱坞电影中唯一被低估的自然灾害。更重要的是，崩溃使科学家不确定导致他们的原因以及他们如何影响我们未来的气候。在每次崩溃之后，已经揭示了浮动的Larsen冰架以前存在的新胚胎，并且内陆冰川内陆已经加速，增加了足够多的额外冰，每年将全球海平面提高0.1 mm。尽管这一数量似乎很小，但科学家现在关注其余拉尔森C部分上游的较大冰场，其中包含足够的冰，将全球海平面提高了50毫米。如果Larsen-C部分崩溃，那冰块将严重危险。我们设计了一系列实验，结合了卫星和田间探索，以解决Larsen Ice架子崩溃的奥秘。我们的测量方法将确定是否应归咎于海洋或气氛。我们将使用敏感的雷达系统 /与道路速度摄像机相似 - 测量冰架厚度的极慢变化每小时约0.1毫米。我们还将在冰架的顶层钻探，并提取冰块，就像树环一样，它告诉我们气候在过去一个世纪中的变化是如何变化的。当与新的冰流和变薄的卫星测量结合使用时，我们的现场测量值将使我们能够检测到浮动的Larsen冰架下方的海洋是否温暖，或者表面上的夏季冰融化是否比预期的要大。一旦确定了崩溃的原因，我们将构建一个冰架的计算机模型，以研究将来它可能如何破裂。我们的实验将确定1995年和2002年灾难性的Larsen冰架倒塌的原因。他们还将确定其余的Larsen-C部分是否会在未来几年变得脆弱。而且，最重要的是，我们将预测如果Larsen-C将来的某个时候倒塌，全球海平面将有多快。