Collaborative Research: Volcanism in the Arctic System (VAST): geochronology and climate impacts

合作研究：北极系统火山活动（VAST）：地质年代学和气候影响

• 批准号: 0714014
• 负责人: Raymond Bradley
• 金额: --
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0714014&HistoricalAwards=false
• 关键词: Collaborative; Research; Volcanism; Arctic; System

This project integrates modeling and paleoenvironmental data to obtain a better understanding of the role of volcanism in the Arctic System, and to better utilize widespread tephra layers to date and synchronize paleoenvironmental records across the Arctic.The Arctic includes major centers of volcanism in the North Atlantic and the North Pacific sectors. Stratospheric aerosols derived from either Arctic or tropical volcanism alter the radiative balance of the Arctic, which in turn influences atmospheric circulation with global consequences. Reduced summer insolation can lead to substantial Arctic cooling of a few years' duration, but these perturbations may produce longer impacts if the system passes through a threshold condition, whereby strong positive feedbacks yield changes in the state of the Arctic System. New paleodata suggest that dramatic increases in terrestrial ice caps in Arctic Canada lasting several centuries occurred following two of the largest eruptions of the past millennium, during the transition into the Little Ice Age. Explosive Arctic volcanism can produce large volumes of source- and time-diagnostic tephra, with extensive distributions. These tephra layers provide time-synchronous marker horizons that constrain the geochronology of paleoenvironmental records and serve to precisely synchronize records derived from lacustrine, marine, and ice-sheet archives, thereby allowing a better assessment of leads and lags in the climate system.An international research team has been assembled to assess the impact of both Arctic and tropical eruptions on the Arctic System through climate modeling and to optimize the utility of tephras in paleoenvironmental studies throughout the North Atlantic Arctic. This represents the US contribution. Specific objectives of this effort include:- Establish a standardized geochemical inventory of Icelandic marker tephra erupted over the past 12,000 years, and develop criteria to differentiate Icelandic from North Pacific tephra.- Improve techniques to identify and extract microtephra from sedimentary archives.- Extend proximal-derived Icelandic tephra geochemical fingerprinting to microtephra in distal lacustrine, marine and Greenland ice-core archives.- Develop generalized maps of plume trajectories for most major Icelandic eruptions.- Evaluate the sensitivity of the Arctic System to high- and low-latitude eruptions through climate modeling and comparisons of model output to paleoenvironmental reconstructions.

该项目整合了建模和古环境数据，以便更好地了解火山活动在北极系统中的作用，并更好地利用广泛的火山灰层来确定和同步整个北极的古环境记录。北极包括北大西洋的主要火山活动中心和北太平洋地区。来自北极或热带火山活动的平流层气溶胶改变了北极的辐射平衡，进而影响大气环流，从而产生全球后果。夏季日照减少可能导致北极持续几年的大幅降温，但如果系统通过阈值条件，这些扰动可能会产生更长时间的影响，从而强烈的正反馈会导致北极系统状态发生变化。新的古数据表明，在进入小冰河时代的过渡期间，加拿大北极地区陆地冰盖的急剧增加持续了几个世纪，发生在过去千年中两次最大的火山喷发之后。北极爆发的火山活动可产生大量具有来源和时间诊断性的火山灰，且分布广泛。这些火山灰层提供了时间同步标记层，限制了古环境记录的地质年代学，并用于精确同步来自湖泊、海洋和冰盖档案的记录，从而可以更好地评估气候系统的超前和滞后。研究小组已组建起来，通过气候模型评估北极和热带火山喷发对北极系统的影响，并优化火山灰在整个北大西洋北极地区古环境研究中的效用。这代表了美国的贡献。这项工作的具体目标包括： - 建立过去 12,000 年来喷发的冰岛标记火山灰的标准化地球化学清单，并制定区分冰岛火山灰和北太平洋火山灰的标准。 - 改进从沉积档案中识别和提取微火山灰的技术。 - 扩展近端火山灰-源自冰岛火山灰的地球化学指纹对远端湖泊、海洋和格陵兰冰芯档案中的微火山灰进行分析。-为大多数国家开发羽流轨迹的通用地图冰岛主要火山喷发。 - 通过气候建模以及模型输出与古环境重建的比较，评估北极系统对高纬度和低纬度火山喷发的敏感性。