Southern Alaska margin: interactions of tectonics, climate, and sedimentation (Integrated Ocean Drilling Program Expedition 341)

在大气二氧化碳浓度较高的情况下，对未来气候变化的预估依赖于我们对不同气候成分之间的关系和反馈的理解，这些关系和反馈可能是过程（海洋环流、冰盖行为），也可能是区域（例如低纬度与高纬度）。现代气候系统中的一些关键变量与过去的重大气候变化有关，但它们是驱动、放大还是响应气候事件，仍然是一个激烈争论的话题。这次研究考察的重点是在靠近南阿拉斯加的样带钻取一系列海洋沉积物岩心，以调查山脉形成、冰盖生长和气候变化之间的联系。近年来的研究表明，山脉隆升可以通过影响降水的路径和强度来影响局地和区域气候。它还会导致冰盖的增长，并加剧对陆地表面的侵蚀。从山区向海洋输送的沉积物和淡水的增加会影响山区附近地区的生物生产力和海洋环流格局。相比之下，也有人提出，在区域尺度上（例如横跨北太平洋）海洋环流的冷却和变化可能对允许或鼓励冰盖的生长很重要，而区域变暖可能对推动冰盖退缩很重要。这种复杂的相互作用很难评估，因为很少有机会恢复长序列的沉积物，这些沉积物既包含气候信号，也包含侵蚀和冰盖生长/衰减的证据。在这次探险中，我们将恢复一系列逐渐靠近海岸的岩心，这些岩心跨越了数百万年，但也保存了快速气候事件和岸上环境条件反应的证据。研究结果将对广泛的学术兴趣具有重要意义，包括气候变化、构造学、生物地球化学循环、冰川学和流域动力学。

Projections of future climate change under higher atmospheric carbon dioxide concentrations rely upon our understanding of the relationships and feedbacks that operate between different climate components, either as processes (ocean circulation, ice-sheet behaviour) or regions (e.g. low versus high latitudes). A number of key variables within the modern climate system have been linked to major climate transitions in the past, but whether they drove, amplified, or responded to climate events remains a topic of intense debate.The focus of this research expedition is to drill a series of marine sediment cores in a transect close to South Alaska, in order to investigate the links between mountain building, ice sheet growth, and climate change. Recent research has shown that the uplift of mountains can affect local and regional climate by affecting the pathways and intensities of precipitation. It can also lead to ice sheet growth, and to increased erosion of the land surface. The increase delivery of sediments and freshwater from the mountains to the ocean can affect biological productivity and the patterns of ocean circulation in areas proximal to the mountains. In contrast, it has also been proposed that cooling and changes in ocean circulation at a regional scale (e.g. across the North Pacific Ocean) could be important for allowing or encouraging the growth of ice sheets, and regional warming might be important for driving ice-sheet retreat.This complex set of interactions has been difficult to assess because there has rarely been an opportunity to recover long sequences of sediments which contain both climate signals and evidence for erosion and ice sheet growth/decay. In this expedition we will recover a series of cores which are progressively closer to shore, which span millions of years but which also preserve evidence for rapid climate events and the response of the environmental conditions onshore. The results will be important for a wide range of academic interests, spanning climate change, tectonics, biogeochemical cycling, glaciology and catchment dynamics.