Collaborative Research: A Synthesis of the Last 2000 Years of Climatic Variability from Arctic Lakes

合作研究：北极湖泊过去 2000 年气候变化的综合

• 批准号: 0450938
• 负责人: Jonathan Overpeck
• 金额: $ 11.1万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-03-01 至 2010-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0450938&HistoricalAwards=false
• 关键词: Collaborative; Research; Synthesis; Last; 2000

This project contributes to understanding the Arctic system by placing 20th century climatic change into a longer-term context of inter-decadal climatic variability spanning the last 2000 yr. The centerpiece of the project is a synthesis of standardized, high-resolution proxy climate records from lakes across the North American Arctic that will advance our understanding of the role of the Arctic within the Earth system.Recent results have demonstrated that proxy climate records from the Arctic preserve a signature of summer temperature that is related to both global mean warming and the Arctic Oscillation. This conclusion was based on a synthesis limited to just the last 600 yr. Available records that extend beyond the Little Ice Age to previous warm intervals are currently too few to capture modes of variability with adequate certainty. The longer-period evolution of these modes is identifiable in decadally resolved proxy records, and should be preserved in longer records of annual to multi-decadal resolution.This synthesis of annual to inter-decadal climatic variability will extend through the key warm interval of Medieval time. The certainty of the climate reconstruction will be significantly improved by nearly tripling the number of high-resolution, 2000-yr-long, proxy climate records currently available in the Arctic. The project facilitates integration of results by standardizing the methodologies and by holding workshops for vested collaborators and their students. This tightly focused synthetic study of the Arctic system will be integrated directly into a climate-modeling effort to explore the role of volcanism and solar irradiance fluctuations versus internal adjustments of the climate system and its inherent modes of variability to explain observed patterns in the proxy climate data.Across the Arctic, lacustrine archives contain the most accessible and widely distributed proxy records for the past 2000 yr. This work focuses on 30 of the PIs' highest-priority, most-promising lakes, nearly all of which have been cored previously. The network of sites includes two regional foci (Alaska and the NW North Atlantic) that generally encompass the nodes of the surface temperature expression for the Arctic Oscillation, thereby facilitating the reconstruction of this mode of variability. Half of the lakes contain laminated sediment with potential for annually resolved records; others have high sedimentation rates for sample resolution of 5 to 30 yr. The proxy data from most lakes can be compared with nearby tree-ring records or instrumental data, or can be applied to transfer functions to yield quantitative estimates of temperature or other climatic variables. Analyses at low-resolution have already begun on most of the cores as part of on-going research. Preliminary data from these lakes indicate their high potential for climate reconstructions.

该项目将20世纪的气候变化放在跨越过去2000年的年代际气候变化的较长期背景下，有助于理解北极系统。该项目的核心是合成北美北极地区湖泊的标准化、高分辨率替代气候记录，这将促进我们对北极在地球系统中作用的理解。最近的结果表明，北极替代气候记录保留了夏季温度的特征，这与全球平均变暖和北极涛动有关。这一结论是基于一项仅限于过去600年的综合。目前，从小冰期延伸到之前的温暖时段的可用记录太少，无法充分确定地捕捉到变化的模式。这些模式的较长周期演变可以在十年分辨率的替代记录中识别，应该保存在较长的年度到数十年分辨率的记录中。这种年到年代际气候变率的合成将延伸到中世纪的关键暖期。通过将北极现有的高分辨率、2000年长的代理气候记录的数量增加近两倍，气候重建的确定性将显著提高。该项目通过标准化方法和为既得利益合作者及其学生举办讲习班，促进了成果的整合。这项对北极系统的密切关注的综合研究将直接整合到气候模拟工作中，以探索火山活动和太阳辐射波动与气候系统内部调整及其固有变化模式的作用，以解释替代气候数据中的观测模式。在整个北极，湖泊档案包含过去2000年来最容易获取和分布最广泛的替代记录。这项工作集中在30个PI最优先、最有希望的湖泊上，几乎所有这些湖泊以前都曾进行过取芯。站点网络包括两个区域中心(阿拉斯加和北大西洋西北部)，它们一般包括北极涛动表面温度表达的节点，从而促进这种变率模式的重建。一半的湖泊含有层状沉积物，有可能每年记录下来；其他湖泊的沉积速率很高，样品分辨率为5到30年。来自大多数湖泊的替代数据可以与附近的树木年轮记录或仪器数据进行比较，或者可以应用于传递函数，以得出温度或其他气候变量的定量估计。作为正在进行的研究的一部分，已经开始对大多数岩心进行低分辨率分析。来自这些湖泊的初步数据表明，它们具有很高的气候重建潜力。