Climate and ocean changes in Arctic-subarctic environments

北极-亚北极环境中的气候和海洋变化

• 批准号: RGPIN-2014-03575
• 负责人: deVernal, Anne
• 金额: $ 5.25万
• 依托单位: Université du Québec à Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=610524
• 关键词: Climate; ocean; changes; Arctic; subarctic

The research program concerns the variability of climate, ocean and environments at high latitudes of the Northern Hemisphere, and their recording by sedimentary archives. It will address fundamental questions about i) the resilience of Arctic sea ice under "warm" climates of the past, ii) the ocean circulation patterns in response to the opening/closure of the Arctic gateways and iii) the pre-Anthropogenic baseline conditions in the Arctic-subarctic realm. Some focus will be put on the sea ice cover, which is a critical climate parameter through ice-albedo feedback responsible for Arctic amplification. The possible disappearance or resilience of Arctic sea ice and their impact on the biota and global climate are critical issues that need to be urgently examined. Whereas the recent decline of Arctic sea ice led to hypothesize the disappearance of perennial ice within 30 years, the rarity of sea ice data prior to satellite observations prevents assessing its natural variability. Moreover, paradoxical indication for multi-year sea ice in the Arctic during warm episodes of the last millions of years, suggests that Arctic sea ice might be a resilient feature in the Late Cenozoic climate system. Similarly, the ocean response to the ongoing warming is not unequivocal, especially in the subarctic basins as the freshwater budget of the Arctic Ocean and its exchanges with the North Atlantic control heat fluxes, salinity, density and convection, i.e., the North Atlantic thermohaline circulation. As a contribution to international initiatives, I intend to reconstruct climate and ocean conditions in the Arctic-subarctic realm, notably for documenting the Earth’s system response under extreme conditions. Special attention will be given to the early Holocene (~10-6 ka), and warm interglacial stages of the Quaternary marked by high insolation, and to the Pliocene (~5.3-2.5 Ma) when forest extended into the Canadian Arctic and atmospheric carbon dioxide peaked at about 400 ppmv. To meet these objectives, access to marine sedimentary archives from Arctic and subarctic seas are needed. Sediments to analyze include cores from ODP (Ocean Drilling Program) and IODP (Integrated ODP) in addition to cores to be collected within the frame of international expeditions. From a methodological point of view, the reconstruction of climate and ocean parameters will be based on the analysis of organic-walled microfossils, notably dinoflagellate cysts, as tracers of planktonic production and sea-surface conditions, and pollen and spores, as proxies for land-sea correlation and terrestrial climate reconstructions, in addition to complementary sedimentological, isotopic and geochemical analyses. Aside the main stream of research, some attention will be paid to ocean and environmental changes over the last centuries, with the aim to fill the gap between instrumental and sedimentary records and to better calibrate quantitative reconstructions from proxies. This work is needed to determine pre-Anthropocene baseline conditions (i.e., prior to instrumental records) and thus improve estimates of anthropogenic trends. It will also permit to assess life-threatening environmental changes (eutrophication, hypoxia, red tides) in coastal settings and will provide a clue on their natural vs human-driven causes. The research program is tightly linked to national and international initiatives (VITALS, ArcTrain, PMIP, IODP) aiming at the monitoring and forecasting of ocean and climate changes in Arctic-subarctic environments, which is indispensable for sustainable development of high latitude regions. It will contribute to the training of students of all levels to address complex issues related to Arctic-subarctic climate change and/or coastal processes.

该研究计划涉及北半球高纬度地区气候，海洋和环境的变化，以及沉积档案的记录。它将解决有关i）过去的“温暖”气候下北极海冰的弹性，ii）ii）响应北极门户的开放/关闭和iii的海洋循环模式）北极 - 贝尔西特氏菌领域的人为基线条件。 通过负责北极扩增的冰山反馈，这是海冰覆盖物的重点，这是一个关键的气候参数。北极海冰的可能消失或韧性及其对生物群和全球气候的影响是需要紧急检查的关键问题。北极海冰最近的下降导致了30年内多年生冰的消失，但在卫星观测之前的海冰数据的稀有性阻止了评估其自然变异性。此外，在过去数百万年的温暖发作中，北极中多年海冰的矛盾指示表明，北极海冰在杜鹃花后期的气候系统中可能是弹性的特征。同样，海洋对正在进行的变暖的反应也不明确，尤其是在亚北极贝斯中，作为北极海洋的淡水预算及其与北大西洋控制热通量，盐度，密度和转化率的淡水预算，即北大西洋热钙循环。 作为对国际举措的贡献，我打算在北极 - 北极领域重建气候和海洋状况，特别是在极端条件下记录地球系统的响应。当森林延伸到加拿大北极和大气的二氧化碳峰值时，将特别关注早期全新世（〜10-6 ka）和以高隔离为标志的第四纪的温暖冰间阶段以及上新世（〜5.3-2.5 mA）。 为了实现这些目标，需要访问来自北极和亚北极海洋的海洋沉积档案。要分析的沉积物包括ODP（海洋钻探计划）和IODP（Integrated ODP）的核心，此外还需要在国际探险框架内收集核心。从方法论的角度来看，气候和海洋参数的重建将基于对有机壁壁微化石的分析，尤其是鞭毛藻类囊肿，作为浮游生物生产和海洋表面条件的示踪剂，以及花粉和孢子的示踪剂，作为土地相关性和地面环境的代理，以及完整的地理位置分析。 除了主要的研究流外，在过去几个世纪中，将向海洋和环境变化提供一些关注，旨在填补器乐和沉积记录之间的空白，并更好地校准代理的定量重建。需要这项工作来确定人类前的基线条件（即在仪器记录之前），从而改善了人为趋势的估计值。它还允许评估沿海环境中威胁生命的环境变化（富营养化，缺氧，红潮），并将提供有关其自然与人类驱动原因的线索。 该研究计划与国家和国际倡议（Vitals，Arctrain，PMIP，IODP）密切相关，旨在监测和预测北极 - 果肉眼环境中海洋和气候变化，这对于高纬度地区的可持续发展是必不可少的。它将有助于培训各个级别的学生，以解决与北极 - 野性气候变化和/或沿海过程有关的复杂问题。