Merging the Arctic paleoceanography into the Earth's global climate/ocean history

* 北冰洋是气候系统的一个重要组成部分，因为它的海冰覆盖通过冰调节能量收支，并与北方太平洋和北大西洋交换，对全球海洋环流发挥作用。然而，它的历史仍然没有得到解决，主要是由于i）缺乏一个强大的沉积档案年表，ii）在北极恢复这些档案的困难，以及iii）环境变化的模糊代理记录。因此，将北冰洋纳入全球地球和海洋气候系统仍然是一个挑战。这是我在今后几年中将重点关注的问题。最近从北冰洋和北大西洋亚北极海采集的沉积物岩心将用于记录北冰洋在最近冰期/间冰期循环期间的状况和相互作用。国际海洋发现计划（IODP）的钻井岩心将用于确定海洋条件开始的日期以及北极盆地随后向新生代晚期常年海冰覆盖的演变。加拿大对国际努力的有力协调参与以及与外国科学家的密切合作，特别是通过关于“北大西洋和加拿大北极地区气候变化的过程和影响”的国际NSERC-CREATE方案与来自德国的科学家的密切合作，构成了本提案的框架。这里计划的研究旨在通过地球化学和放射年代学调查，为合作伙伴对北冰洋海脊和亚北极海岩芯的研究作出贡献。其主要目的是：（1）根据铼-锇同位素研究，更好地确定北冰洋海侵的时代及其新生代演化;（2）根据最近采集的岩芯中沉积物中铀系同位素的衰变，建立一个一致同意的晚第四纪北极海脊年代地层记录; ㈢进一步开发地球化学和同位素示踪剂，以确定过去和现在北冰洋内以及在过去温暖时期和目前变暖趋势期间流向邻近亚北极海的通量。这项工作旨在为在其他供资机构支持的国际研究倡议框架内开展的气候和地球化学建模工作提供关键信息。一批在环境同位素地球化学和/或地球化学和气候建模方面接受过最先进培训的研究生将直接参与该计划。

***The Arctic Ocean is an important component of the climate system because of its sea-ice cover modulating energy budget through albedo, and of its exchanges with the northern Pacific and North Atlantic that play a role on the global ocean circulation. However, its history is still unresolved, notably due to i) the lack of a robust chronology from sedimentary archives, ii) difficulties in recovering such archives in the Arctic, and iii) equivocal proxy records of environmental changes. Hence merging the Arctic Ocean into the global Earth and ocean climate system remains a challenge. This is the issue I will focus on in the forthcoming years. Sediment cores recently raised from the Arctic Ocean and the subarctic seas of the North Atlantic will be used for the documenting of the status and interactions of the Arctic Ocean during recent glacial/interglacial cycles. Drill cores from the International Ocean Discovery Program (IODP) will be used for the dating of the inception of marine conditions and the subsequent evolution of the Arctic basin towards the late Cenozoic perennial sea ice cover. A strongly coordinated Canadian participation to international efforts and tight collaborations with foreign scientists, notably from Germany through the International NSERC-CREATE program on "processes and impacts of climate change in the North Atlantic Ocean and the Canadian Arctic" (ArcTrain), provide the frame of the present proposal. The research planned here aims at contributing to partner studies of cores from Arctic Ocean ridges and subarctic Seas with geochemical and radiochronological investigations. The three main objectives are : i) to better constrain the age of the marine invasion of the Arctic Ocean and its Cenozoic evolution based on Rhenium-Osmium isotope studies and; ii) to set a consensual Late Quaternary chronostratigraphy of Arctic ridge records, based on the decay of Uranium series isotopes in sediments from recently recovered cores; iii) to further develop geochemical and isotopic tracers of past and present fluxes within the Arctic Ocean and towards adjacent subarctic seas during warm episodes of the past and the present warming trend. This work aims at providing critical information for climate and geochemical modelling efforts undertaken within the framework of international research initiatives supported by other funding agencies. A cohort of graduate students with state-of-the-art training in environmental isotope geochemistry and/or geochemical and climate modelling will be directly involved in the program.