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反照率调节能量收支，它与北太平洋和北大西洋的交换对全球海洋循环起着作用。然而，它的历史仍然悬而未决，主要是因为：i)缺乏可靠的沉积档案年代学，ii)在北极恢复这类档案的困难，以及iii)环境变化的模棱两可的代理记录。因此，将北冰洋并入全球地球和海洋气候系统仍然是一项挑战。这是我在未来几年将重点关注的问题。最近从北冰洋和北大西洋次北冰洋升起的沉积物岩芯将用于记录北冰洋在最近的冰川/间冰期周期中的状况和相互作用。国际海洋发现计划(IODP)的钻探岩芯将用于测定海洋条件的开始和随后北极盆地向新生代晚期常年海冰覆盖演化的年代。加拿大对国际努力的大力协调参与以及与外国科学家的密切合作，特别是来自德国的科学家通过国际NSERC-CREATE计划(ArcTrain)关于“北大西洋和加拿大北极气候变化的过程和影响”(ArcTrain)，为本提案提供了框架。计划在这里进行的研究旨在促进对北冰洋海脊和亚北冰洋岩心的合作研究，同时进行地球化学和放射性年代学调查。三个主要目标是：(1)根据Re-Osm同位素研究，更好地限制北冰洋海洋入侵的年龄及其新生代演化；(2)根据最近回收的岩心沉积物中铀系列同位素的衰变，编制一致的晚第四纪北冰洋海脊年代地层学记录；(3)进一步研究过去和现在北冰洋内部和向邻近次北极海域在过去暖期和现在变暖趋势期间的通量的地球化学和同位素示踪剂。这项工作的目的是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模拟工作提供重要信息。一批在环境同位素地球化学和/或地球化学和气候模型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.