Anthropogenic Forcing of Antarctic Ice Loss (AnthroFAIL)

南极冰损的人为强迫（AnthroFAIL）

• 批准号: NE/X000397/1
• 负责人: Paul Holland
• 金额: $ 63.42万
• 依托单位: British Antarctic Survey
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX000397%2F1
• 关键词: Anthropogenic; Forcing; Antarctic; Ice; Loss

Melting ice caps are widely viewed as illustrative of anthropogenic global warming. The largest ice mass on Earth - Antarctica - is losing ice, and may contribute 1 metre or more to global sea level by 2100. However, it is not clear that this ice loss has been caused by human activities. Instead, this ice sheet may be simply responding to natural variability in the climate system.Antarctic ice loss is primarily caused by increased melting of the ice sheet by the ocean. However, it is not known why this melting has changed. The deep ocean waters melting the West Antarctic Ice Sheet have been buried in the deep ocean for centuries, and have not simply warmed alongside the rest of the climate. Instead, changes in the winds are thought to have altered the transport of these warm waters towards Antarctica.This leads to two main possibilities for why Antarctica is losing ice. Firstly, anthropogenic changes in the winds, caused by greenhouse gases and/or the ozone hole, may have gradually increased the supply of warm water towards the ice sheet. Alternatively, natural variability of the winds may have caused a period of high melting that triggered a self-sustaining ice sheet retreat.It is now urgent that we understand whether human activities have increased the ocean melting of Antarctica. If the ice loss is caused by human activities, we must identify the best strategy for minimising future change. If the ice loss is natural and inevitable, we must prepare for the sea-level rise that will play out over the coming centuries. This project will carefully unpick the contributions of natural and human influences using computer simulations of the ocean surrounding West Antarctica. We will first use historical winds from climate models to drive a set of ocean simulations that comprise our 'best guess' of the real history of ocean melting of Antarctica since 1920, under all natural and human forcings. These simulations will be tested against available historical observations from ships, autonomous vehicles, and ocean sediment cores.Once we have this model history, we will work out how it has been influenced by each of the different forcings. We will perform large sets of ocean simulations with and without human greenhouse gases, the ozone hole, and natural climate variability. These simulations will tell us the contribution of each forcing to the oceanic melting of the West Antarctic Ice Sheet. When we have a good understanding of the role of historical forcings, we will be equipped to assess the impact of future forcings. The ozone hole is expected to recover before 2100, so the question is to what extent future emissions of greenhouse gases will overwhelm this recovery, and continue unchecked thereafter. This research will address the fundamental questions of whether humans have caused Antarctic ice loss, and whether there is anything we can now do about it. The answers to these questions are urgently needed to clarify our options for preventing or adapting to future sea-level rise.

冰盖融化被广泛认为是人为全球变暖的例证。地球上最大的冰块——南极洲——正在失去冰，到2100年可能使全球海平面上升1米或更多。然而，目前尚不清楚这种冰的损失是由人类活动造成的。相反，这个冰盖可能只是对气候系统的自然变化做出了反应。南极冰的损失主要是由海洋使冰盖融化加剧造成的。然而，目前尚不清楚为什么这种融化发生了变化。融化南极西部冰盖的深海海水已经在深海中埋藏了几个世纪，并没有像其他气候一样简单地变暖。相反，风向的变化被认为改变了这些温暖的海水向南极洲的输送。这就导致了两种主要的可能来解释为什么南极洲正在失去冰。首先，由温室气体和/或臭氧空洞引起的人为的风的变化可能逐渐增加了流向冰盖的温水供应。另一种可能是，风的自然变化可能导致了一段时间的高融化，从而引发了自我维持的冰盖退缩。现在，我们迫切需要了解人类活动是否加剧了南极洲的海洋融化。如果冰的损失是由人类活动造成的，我们必须确定将未来变化最小化的最佳战略。如果冰的消失是自然的、不可避免的，那么我们必须为海平面上升做好准备，海平面上升将在未来几个世纪内上演。该项目将通过对西南极洲周围海洋的计算机模拟，仔细分析自然和人类影响的贡献。我们将首先使用气候模型中的历史风来驱动一套海洋模拟，这些模拟包括我们对自1920年以来在所有自然和人为力量下南极海洋融化真实历史的“最佳猜测”。这些模拟将根据船舶、自动驾驶车辆和海洋沉积物岩心的现有历史观测结果进行测试。一旦我们有了这个模型的历史，我们就会弄清楚它是如何受到每种不同力量的影响的。我们将进行大量的海洋模拟，无论有没有人类温室气体、臭氧空洞和自然气候变率。这些模拟将告诉我们每种强迫对南极西部冰盖海洋融化的贡献。当我们对历史作用力的作用有了很好的理解，我们就有能力评估未来作用力的影响。臭氧层空洞预计将在2100年之前恢复，因此问题是，未来温室气体的排放将在多大程度上压倒这种恢复，并在此后继续不受控制。这项研究将解决一些基本问题，即人类是否造成了南极冰层的融化，以及我们现在是否可以对此做些什么。我们迫切需要这些问题的答案，以明确我们预防或适应未来海平面上升的选择。