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，并且它与北太平洋和北大西洋的交换在全球海洋环流中发挥作用。然而，其历史仍未得到解决，主要是由于i)沉积档案中缺乏可靠的年代学，ii)在北极恢复这些档案困难重重，以及iii)环境变化的模糊代用记录。因此，将北冰洋并入全球地球和海洋气候系统仍然是一个挑战。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亚北极海域升起的沉积物岩心将用于记录北冰洋在最近冰期/间冰期旋回期间的状况和相互作用。来自国际海洋发现计划（IODP）的岩心将用于确定海洋条件开始的年代，以及北极盆地随后向晚新生代多年生海冰覆盖的演变。加拿大大力协调参与国际努力，并与外国科学家密切合作，特别是来自德国的国际NSERC-CREATE项目“北大西洋和加拿大北极地区气候变化的过程和影响”（ArcTrain），为本提案提供了框架。这里计划进行的研究旨在促进北冰洋脊和亚北极海岩心与地球化学和无线电年代学调查的合作研究。三个主要目标是：i)基于铼锇同位素研究更好地约束北冰洋海洋入侵的年龄及其新生代演化；ii)根据最近回收的岩心沉积物中铀系同位素的衰变，建立一个公认的北极脊晚第四纪年代地层记录；（三）进一步开发过去和现在北冰洋内以及过去和现在暖期和现在暖期期间流向邻近亚北极海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助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受过最先进训练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.