Collaborative Research: Centennial-to-Millennial-Scale Climatic Fluctuations in Northeast Siberia during the Last Glacial Cycle

对地球历史的研究表明，气候能够迅速变化(在几年或几十年内)和剧烈变化(从冰期到间冰期)。地球生态系统对这种全球范围变化的反应在空间上可能是复杂的。在上一次冰川周期(约12000年和11万年前)，古气候波动很明显，当时温度通常比现在低，并被24次温暖事件打断，在此期间，温度在15-20摄氏度之间。了解这种环境变化的机制和时间对北极特别重要，因为北极对气候变化特别敏感。从历史上看，格陵兰冰盖数据一直是该地区古气候重建的基础。然而，仍然缺乏对北方生态系统如何响应气候变化的了解。这项研究将通过提供第一个连续的、高分辨率的、多代理记录的约22,000至50,000年前北极的古植被和古气候变化来解决这一认识差距。将从西伯利亚东北部埃利克昌湖的一个沉积物岩芯中提取并分析花粉和硅藻遗骸以及沉积物地球化学，并将其与在冰芯中发现的气候趋势进行充分的时间控制。这些新数据将被用来定义气候波动的数量、幅度和时间，以评估北极东部(北大西洋)和西部(西伯利亚东北部)气候历史的异同。具体而言，这项研究将：1)评估对北亚过去温度与北大西洋区域气候和海洋变化有关的计算机模拟；2)探讨西伯利亚在将源于北大西洋的气候波动传递给北太平洋方面的作用；3)研究生态系统对各种气候条件的反应范围以及生物反馈对气候系统的潜在重要性(例如，作为主要甲烷来源的北方森林的分布的变化是否会影响大气中甲烷的水平)。

Studies of Earth's history show that climate is capable of changing rapidly (within a few years or decades) and dramatically (from glacial to interglacial conditions). The response of the Earth's ecosystems to such global-scale changes can be spatially complex. Paleoclimatic fluctuations are evident during the last glacial cycle (~12,000 and 110,000 years ago) when temperatures were generally cooler than present and were interrupted by 24 warm events during which temperature ranged from 15-20 degrees C. Understanding the mechanisms and timing of such environmental change is particularly important for the Arctic, a region particularly sensitive to climate variability. Historically, data from the Greenland ice sheet has been the foundation for paleoclimatic reconstruction for the region. Still lacking, however, is an understanding of how northern ecosystems have responded to changes in climate.This research will address this knowledge gap by providing the first continuous, high-resolution, multi-proxy record of paleovegetational and paleoclimatic change from the Arctic for the period ~22,000 to 50,000 years ago. A sediment core from Elikchan Lake in northeast Siberia will be recovered and analyzed for pollen and diatom remains as well as sediment geochemistry with sufficient temporal control to be compared to climate trends found in ice cores. These new data will be used to define the number, magnitude, and timing of climatic fluctuations to assess the similarities and differences in the climate histories between the eastern (North Atlantic) and western (northeast Siberia) Arctic. Specifically, the research will: 1) evaluate computer simulations of past temperature in northern Asia as related to climatic and oceanic changes in the North Atlantic region; 2) explore the role of Siberia in transmitting climatic fluctuations originating in the North Atlantic to the North Pacific; and 3) examine the range of ecosystem responses to various climatic conditions and the potential importance of biofeedback to the climate system (e.g., whether changes in the distribution of boreal forests, a major methane source, can affect levels of methane in the atmosphere).