The ice age, oceans and climate: triggers of iceberg calving and rapid temperature change

冰河时代、海洋和气候：冰山崩解和温度快速变化的触发因素

• 批准号: 2296235
• 金额: --
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2296235
• 关键词: ice; age; oceans; climate; triggers

This PhD project will use numerical modelling in order to establish the complex chain of events that took place early in the last deglaciation, linking catastrophic ice sheet collapse, iceberg armadas, rapid cooling, abrupt warming and the complete reorganisation of largescale Atlantic Ocean circulation. The candidate will explore possible mechanisms that link these different parts of the earth system, undertaking high profile research to examine existing hypotheses and create news ones to understand the cause and consequences of rapid climate change in the high latitudes.BACKGROUNDAt the Last Glacial Maximum (21,000 years ago), vast ice sheets stretched across much of the Northern Hemisphere, covering large expanses of North America, Greenland and Eurasia. As climate warmed, and the ice sheets began retreating, an intriguing chain of events was triggered in the North Atlantic. Largescale ocean circulation slowed, climate cooled, armadas of icebergs were released, ocean circulation rapidly strengthened and temperatures abruptly rose. Although well documented individually (Heinrich Stadial 1, Heinrich Event 1, the Bolling Warming), it remains unknown precisely how and even if these events were linked. Two recent studies put forward the tentative hypothesis that melting of the Eurasian ice sheet caused ocean circulation to slow-down, cooling the North Atlantic region and triggering enhanced iceberg calving from the Eurasian ice sheet. This amplified the initial change, increasing iceberg production from North America and sustaining the cooling. But, this chain of events has never been tested. Furthermore, it remains unclear what caused the last of these events; the abrupt Bolling Warming. Was it a rapid reduction in the amount of meltwater reaching the ocean? Was a critical threshold in atmospheric CO2 crossed? Or was it simply the result of an inherently unstable climate regime? The last deglaciation is the best documented period of abrupt climate change, yet we do not understand how and why the recorded events took place. This exciting project tackles this challenge, testing ice-ocean-atmosphere interactions to produce seminal new knowledge of our climate.Please contact the lead supervisor ([e-mail]) for more information and before applying.PROJECT AIMThe candidate will run complex numerical climate and ice sheet models to examine the interplay between climate, icebergs and ocean circulation in the early period of the last deglaciation (21-14.5 thousand years ago). The overall aim is to establish the chain of events surrounding Heinrich Stadial 1, involving ice sheet melting, a rapid slowdown of the largescale Atlantic Ocean circulation (Atlantic Meridional Overturning Circulation, AMOC), North Atlantic cooling, enhanced iceberg discharge from the Eurasian and North American ice sheets (Heinrich Event 1), a resumption of the AMOC and abrupt warming (Bolling Warming).

这个博士项目将使用数值模拟来建立在最后一次冰川消融早期发生的复杂的事件链，将灾难性的冰盖坍塌、冰山舰队、快速冷却、突然变暖和大规模大西洋环流的完全重组联系在一起。候选人将探索连接地球系统这些不同部分的可能机制，进行高调研究以检验现有假说并创造新的假说，以了解高纬度地区快速气候变化的原因和后果。背景：最后一次冰川盛期(21,000年前)，横跨北半球大部分地区的巨大冰盖，覆盖了北美、格陵兰和欧亚大陆的大片地区。随着气候变暖，冰盖开始消退，在北大西洋引发了一系列有趣的事件。大范围的海洋环流减缓，气候变冷，冰山舰队被释放，海洋环流迅速加强，气温突然上升。尽管有很好的记录(海因里希·斯塔尔1，海因里希事件1，博林变暖)，但这些事件到底是如何联系在一起的，甚至是否联系在一起，仍然是未知的。最近的两项研究提出了一个初步假设，即欧亚冰盖的融化导致海洋环流放缓，使北大西洋地区降温，并引发欧亚冰盖冰山崩解的增强。这放大了最初的变化，增加了北美冰山的产量，并维持了降温。但是，这一系列事件从未经受过考验。此外，目前还不清楚是什么导致了最后一次事件：突然的博林变暖。是不是流入海洋的融水数量迅速减少了？大气中的二氧化碳是否超过了一个临界阈值？或者，这仅仅是天生不稳定的气候制度的结果？最后一次冰川消融是记录最充分的气候突变时期，但我们不知道记录的事件是如何发生的，为什么会发生。这个令人兴奋的项目解决了这一挑战，测试了冰-海洋-大气的相互作用，以产生关于我们气候的开创性的新知识。请联系首席主管([e-mail])了解更多信息，并在应用之前。项目目标候选人将运行复杂的数值气候和冰盖模型，以研究气候、冰山和海洋环流之间的相互作用，在最后一次冰川消融早期(21-14.5年前)。总体目标是建立海因里希阶梯1周围的一连串事件，包括冰盖融化、大尺度大西洋环流(大西洋子午线翻转环流)的迅速减缓、北大西洋冷却、欧亚和北美冰盖冰山排放增加(海因里希事件1)、海因里希环流恢复和突然变暖(博林变暖)。