Isolating the Larsen-C Ice Shelf Mass Instability

1988年，世界气象组织和联合国成立了一个由专家科学家组成的国际小组，收集有关气候变化的信息，以回应公众对全球变暖和地球臭氧层空洞等问题日益增长的关注。从那时起，该小组的主要调查结果表明，气温和海平面上升的速度超过了自然变化的解释，20世纪世纪工业化的污染物可能是一个因素。地球现今的气候变化与其极地地区的冰冻结密切相关。随着气温上升，冰融化并流入海洋，导致海平面上升。这种简单关系的代价可能是巨大的。如果南极洲的冰层迅速融化，其数量足以使全球海平面上升65米，这一变化将淹没世界20个最大城市中的13个，包括伦敦。地球上一些最快的气候变化发生在南极洲半岛，南极洲最温暖的地区，智利和阿根廷的正南方。自19世纪世纪早期探索以来，那里的气温测量显示，在过去的100年里，气温上升了5摄氏度以上。也许有史以来最剧烈的气候变化发生在过去的十年里，在1995年和2002年，漂浮的拉森冰架的巨大部分-拉森-A和/B，每个都有康沃尔郡那么大-分解成数千座冰山，引起了广泛的恐慌。这些事件在去年的大片《后天》的开幕式上被描绘成一个孤立的裂缝，这是一场真正的灾难，可能是好莱坞电影中唯一被低估的自然灾害。更重要的是，这些崩塌让科学家们不确定是什么原因造成的，以及它们如何影响我们未来的气候。在每次崩溃之后，新的海湾已经出现在漂浮的拉森冰架曾经存在的地方，这些海湾的内陆冰川已经加速，崩解足够的额外冰，每年使全球海平面上升0.1毫米。尽管这个数量看起来很小，但科学家们现在担心的是拉森-C部分上游的更大的冰原，它含有足够的冰，可以使全球海平面上升50毫米以上。我们设计了一系列实验，结合卫星和实地勘探，以解开拉森冰架坍塌之谜。我们的测量将确定海洋或大气的变化是否是罪魁祸首。我们将使用一个灵敏的雷达系统/类似于公路速度摄像机-测量冰架厚度的极其缓慢的变化，每小时约0.1毫米。我们还将钻穿冰架的顶层，提取冰核，就像树木的年轮一样，告诉我们气候在过去世纪是如何变化的。当与新的卫星测量冰流和变薄相结合时，我们的实地测量将使我们能够检测漂浮的拉森冰架下的海洋是否比预期的要温暖，或者夏季冰在表面融化是否比预期的要大。一旦确定了崩塌的原因，我们将建立一个冰架的计算机模型，以研究它在未来可能如何断裂。我们的实验将确定1995年和2002年灾难性的拉森冰架崩溃的原因。他们还将确定剩余的拉森-C段在未来几年是否会变得脆弱。而且，最重要的是，我们将预测如果拉森-C在未来某个时候崩溃，全球海平面将以多快的速度上升。

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.