iSTAR-C - Dynamical control on the response of Pine Island Glacier

预计海平面上升将在未来几十年至几个世纪影响全世界的沿海社区。在英国，沿海社区和资产的脆弱性最能体现在海防设施可能发生漫顶的频率上。例如，伦敦市的海防（包括泰晤士河屏障）在建造时，是为了防止伦敦千年一遇的洪水。全球海平面上升50厘米将使这一保护水平降低到1-100年，上升100厘米将使其降低到1/10年。松岛冰川是南极洲西部五个冰川之一，目前正以显著和加速的速度造成海平面上升。受变薄影响的海流部分含有足够的冰，可使全球海平面上升约25厘米，其邻近地区又增加了50厘米。考虑到冰损失的速度和对海防规划的潜在影响，显然需要了解和预测松岛冰川及其邻近地区的未来。然而，正如政府间气候变化专门委员会（2007年）所强调的，人们对动态变化通过冰川排空冰盖的方式的了解非常少，因此，政府间气候变化专门委员会认为，这是对未来世纪海平面上升的最不了解的，而且可能是最大的贡献。通过寻求理解负责传递浮冰架变薄效应的过程，因此，现在可以在松岛冰川的大部分主干和支流上看到变薄。ISTAR-C还将使用最先进的方法来测量这些特性。（岩石类型和含水量）的床下在松岛冰川的几个位置，以确定其对传播的影响。我们将检验这样一个假设，即正是这些河床条件导致了松岛冰川的支流似乎以不同的速率变薄，这将使我们更好地了解冰川未来冰变薄速率的大小。为了实现这些目标，我们将收集数据从松岛冰川在两个领域的季节。这将包括精确测量冰流的变化，从冰架上升到冰川并进入其支流。我们将使用雷达和地震技术对冰川床进行成像，使用卫星测量地面无法到达的地区冰川的变化结构。我们将使用我们收集到的数据来驱动和验证一组松岛冰川动态的计算机模拟。每一个都将测试冰川流动的一个特定方面，并使我们能够根据真实的数据来测试我们目前的知识和假设。从演习中产生的模型在模拟冰川过去的变化方面将更加可靠，从而减少了预测这种变化未来演变的不确定性，以及对海平面上升的影响。总体而言，这一计划将大大提高对冰川一般如何与其河床相互作用的理解，这是关于地球上变化最快、最重要的冰川之一，松岛冰川的非常具体的课程。

It is expected that sea-level rise will impact coastal communities worldwide over the coming decades to centuries. In the UK, the vulnerability of coastal communities and assets is best characterised in terms of the likely frequency of the over-topping of sea-defences. For example, when they were built, the sea-defences for the city of London (including the Thames Barrier) were designed to protect London 1-in-1000 year flooding. A rise of 50 cm in global sea level will reduce this level of protection to 1-100 years, and a rise of 100 cm would reduce it to 1-in-10 years. Pine Island Glacier is one of five glaciers in West Antarctica that are currently contributing sea-level rise at a significant and accelerating rate. The portion of current affected by thinning contains sufficient ice to raise global sea-level by around 25 cm - its neighbours account for another 50 cm. Given the rate of ice-loss and the potential implications for sea-defence planning there is a clear requirement to understand and predict the future of Pine Island Glacier and its neighbours. However, as highlighted by the Intergovernmental Panel on Climate Change (2007) understanding the way that dynamic changes are transmitted through the glaciers draining ice sheets is so poorly understood that the IPCC believed it was the least well understood, and potentially the largest, contribution to sea-level rise in the coming century.ISTAR-C will directly address this lack of knowledge, by seeking to understand the processes that are responsible for transmitting the effect of thinning of the floating ice shelf, upstream such that thinning can now be seen on much of the trunk and tributaries of Pine Island Glacier.ISTAR-C will also use the most up-to-date methods available to measure the properties (rock-type and water-content) of the bed beneath at several locations on Pine Island Glacier to determine their influence on the propagation of thinning. We will test the hypothesis that it is these bed conditions are responsible for the fact that the tributaries of Pine Island Glacier appear to be thinning at different rates, which will give us a much better understanding on which to predict the future magnitudes of ice-thinning rates for the glacier. To achieve these objectives we will collect data from Pine Island Glacier during two field seasons. These will include precise measurement of variations in ice-flow from the ice-shelf up the glacier and into its tributaries. We will image the bed of the glacier using radar and seismic techniques, use satellite to measure the changing configuration of the glacier in areas that cannot be accessed on the ground. We will use the data we have collected to drive and verify a set of computer simulations of the dynamics of Pine Island Glacier. Each of these will test a particular aspect of the glacier flow, and allow us to test our current knowledge and hypotheses against real data. The models that emerge from the exercise will be demonstrably more reliable in simulating past changes on the glacier, and thus have reduced uncertainty in predicting the future evolution of such changes, and the consequential contribution to sea-level rise.Overall, this programme will deliver significant improvements in understanding of how glaciers in general interact with their beds, and very specific lessons about one of the most rapidly-changing and significant glaciers on the planet, Pine Island Glacier.