Investigating the potential contribution of the East Antarctic Ice Sheet to future sea level change.

目前，南极冰盖(AIS)在近期和长期内对全球海平面变化的潜在贡献存在重大不确定性。AIS的一部分位于低于海平面的陆地上，因此与其他位于海平面以上的陆地部分具有非常不同的流态。因此，它很容易受到海洋环流和大气变化的影响。海洋温度的微小变化可能会对冰流产生很大影响，而大气温度则需要大幅变化(在AIS上空，大气温度一般比冰点低几十度)。有一种假设表明，海洋冰盖(那些躺在海平面以下的海床上的冰盖)也有一个加深到内陆的冰层，由于它们的结构，本质上是不稳定的。接地线(冰盖从固定到漂浮的位置)的小范围变薄/后退会使冰层变薄，那里的冰层更深，冰不再能够接地，因此由于基阻增加，流动更快。这导致了一种反馈机制，在最糟糕的情况下，可能会导致冰盖的大部分破裂。到目前为止，较小的西部AIS(WAIS)一直是最令人担忧的地区，大部分冰盖停留在海平面以下的海床上，在其中一个排水部门(阿蒙森海地区)观察到强烈的变薄信号。较大的EAIS(EAIS)此前被认为是稳定的，因为大部分冰盖位于海平面以上的陆地上。然而，已知有一些大型盆地低于海平面(威尔克斯和奥罗拉冰下盆地)，尽管目前从这些盆地获得的数据很少。这些地区的冰目前也在沿海地区附近表现出表面变薄的信号，这不能用降雪模式的变化来解释，因此肯定有一个动态的起源。冰盖稳定性和未来海平面变化的不确定性部分来自于数值模型在再现发生在接地线上的过程方面的不足，从而在反映接地线位置的变化方面存在不足。最近的模型发展正在改进接地线过程的代表性，一个主要的数据收集特派团将在不久的将来提供关于两个EAIS海洋盆地基岩性质的详细信息。这两项进展将使人们能够通过数值冰盖模拟更好地理解EAIS稳定性的本质。因此，这项研究建议使用一种先进的冰盖数值模式来调查EAIS海洋部分的变化动态，以调查冰盖未来的稳定性及其对未来全球海平面变化的潜在贡献，无论是在不久的将来，还是在十年和千年尺度上。这项工作将在达勒姆大学进行，与爱丁堡大学和布里斯托尔大学南极研究前沿的其他研究人员以及英国南极调查局合作进行。了解和量化全球海平面的冰盖稳定性和未来变化，与当前对全球环境变化及其对生活在低洼地区的数百万人的影响的关切高度相关。因此，这项研究是及时的，并与当前的研究优先事项相关。

There is currently major uncertainty about the potential contribution of the Antarctic Ice Sheet (AIS) to global sea level change in the immediate and long term future. Part of the AIS rests on land that is below sea level and, hence, has a very different flow regime to other parts which rest on land above sea level. It is, therefore, susceptible to changes in ocean circulation as well as atmospheric change. A small change in ocean temperatures can have a large impact on ice flow, whereas a large change is required in atmospheric temperatures (which are in general tens of degrees below freezing over the AIS). A hypothesis exists that suggests marine based ice sheets (those that rest on bed below sea level) which also have a bed which deepens inland, are inherently unstable due to their configuration. A small thinning/retreat in the grounding line (the location where the ice sheet changes from being grounded on its bed to floating) makes the ice thinner inland where the bed is deeper, the ice is no longer able to ground and hence flows faster due to increased basal resistance. This leads to a feedback mechanism that could, in the worst case, lead to the breakup of large parts of the ice sheet. The smaller West AIS (WAIS) has so far been the region of greatest concern, with most of the ice sheet resting on bed below sea level and a strong thinning signal observed in one of the drainage sectors (Amundsen Sea sector). The larger East AIS (EAIS) has previously been considered to be stable, as the majority of the ice sheet rests on land above sea level. However, there are some large basins known to be below sea level (Wilkes and Aurora subglacial basins), though there is currently sparse data coverage from these basins. The ice in these regions is also currently exhibiting a surface thinning signal near the coastal regions that cannot be explained by changes in the snowfall pattern and hence must have a dynamic origin. Part of the uncertainty over ice sheet stability and future sea level change comes from the inadequacy of numerical models in reproducing the processes which occur at the grounding line, and hence in representing change in its location. Recent model developments are improving the representation of grounding line processes and a major data collection mission will in the near future provide detailed information about the nature of the bedrock in the two EAIS marine basins. These two advances will allow a better understanding of the nature of EAIS stability to be derived though numerical ice sheet modelling. This research, therefore, proposes to use an advanced numerical ice sheet model to investigate the changing dynamics of the marine sectors of the EAIS, in order to investigate the future stability of the ice sheet and its potential contribution to future global sea level change in both the immediate future, and on a decadal and millennial scale. The work will be carried out at the University of Durham, in association with other researchers at the forefront of Antarctic research at the Universities of Edinburgh and Bristol, and the British Antarctic Survey. Understanding and quantifying ice sheet stability and future change in global sea level is highly relevant to current concerns about global environmental change and its impact on millions of people living in low lying regions. The research is therefore timely and relevant to current research priorities.