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首页> 外文学位 >Interglacial temperature variability in the high-latitude North Atlantic region inferred from subfossil midges, Baffin Island (Arctic Canada) and Iceland.
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Interglacial temperature variability in the high-latitude North Atlantic region inferred from subfossil midges, Baffin Island (Arctic Canada) and Iceland.

机译：从化石mid，巴芬岛（加拿大北极）和冰岛推断高纬度北大西洋地区的冰间温度变化。

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摘要

Paleoclimate records provide our only empirical data regarding the long-term workings of Earth's climate, and as such play an essential role in understanding natural and anthropogenic climate change. This dissertation presents Holocene paleotemperature records from four lakes in the sensitive high-latitude North Atlantic region, and a pre-Holocene temperature record from one of these sites. Quantitative transfer functions are used to infer paleotemperatures based upon assemblages of subfossil midges (Diptera: Chironomidae) preserved in radiocarbon and luminescence-dated lake sediments.; Midge data from three Icelandic lakes indicate that the north Iceland coast was cooler than present throughout the early to middle Holocene. This contrasts with many sites on Iceland and across the Arctic that experienced an early to mid-Holocene "thermal maximum" in response to enhanced summer insolation forcing. Suppressed terrestrial temperatures along the northern coastal fringe of Iceland were most likely a result of sea surface conditions on the North Iceland shelf.; In contrast, peak warmth on northeastern Baffin Island occurred during the first millennia of the Holocene, roughly in phase with peak insolation forcing. The magnitude of early Holocene warmth at Lake CF8 (5°C warmer than present) far exceeds hemispheric averages, and implies that powerful positive feedbacks enhanced radiative forcing in this region. Early Holocene warmth was interrupted by two cold reversals between 9.5 and 8 ka, which may correlate with the well-known "8.2 event" and widespread abrupt climate changes that occurred ca. 9.2 ka. Maximum last-interglacial temperatures at Lake CF8 were not significantly different from peak Holocene temperatures. This is surprising given that temperatures during the last interglacial period apparently exceeded peak Holocene temperatures at many sites around the high-latitude Northern Hemisphere.; This research adds to growing evidence for spatial heterogeneity in the climatic response to insolation forcing, as well as non-linear climatic and environmental responses to both abrupt perturbations and gradual changes in radiative forcing during interglacial periods. Climate is clearly modulated by local- and regional-scale factors that complicate the response to global- and hemispheric-scale forcings, and add to the challenge of forecasting future climate change.
机译：古气候记录仅提供了我们有关地球气候长期工作的经验数据，因此在理解自然和人为气候变化方面发挥着至关重要的作用。本文介绍了北大西洋敏感高纬度地区四个湖泊的全新世古温度记录，以及其中一个地点的全新世前温度记录。定量传递函数用于根据保存在放射性碳和发光日期湖沉积物中的亚化石mid（Diptera：Chironomidae）的组合推断古温度。来自三个冰岛湖泊的蚊数据表明，整个全新世早期到中期，冰岛北部海岸的温度都比现在低。这与冰岛和整个北极地区的许多站点形成了全新世初期至中期的“高温最大值”，这是由于夏季日照强迫的增强所致。冰岛北部沿海边缘的陆地温度下降很可能是冰岛北部陆架海面条件的结果。相反，全新世的第一个千年期间，巴芬岛东北部出现了暖峰，大致与日照强迫成正比。 CF8湖的全新世早期暖化幅度（比现在高5℃）远远超过了半球平均水平，这意味着强大的正反馈增强了该区域的辐射强迫。全新世早期的温暖被9.5和8 ka之间的两次寒冷逆转所中断，这可能与众所周知的“ 8.2事件”和大约在大约20年前发生的广泛的突然气候变化有关。 9.2卡。 CF8湖的上一次最大冰间温度与全新世峰值温度没有显着差异。考虑到最后一个冰期之间的温度明显超过了北半球高纬度地区许多地方的全新世峰值温度，这令人惊讶。这项研究为日照强迫的气候响应中的空间异质性以及冰期间辐射强迫的突然扰动和逐渐变化的非线性气候和环境响应提供了越来越多的证据。气候显然受到地方和区域尺度因素的调节，这使得对全球和半球尺度强迫的响应变得复杂，并增加了预测未来气候变化的挑战。

著录项

  • 作者

    Axford, Yarrow Larue.;

  • 作者单位

    University of Colorado at Boulder.;

  • 授予单位 University of Colorado at Boulder.;
  • 学科 Geology.; Environmental Sciences.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 273 p.
  • 总页数 273
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;环境科学基础理论;
  • 关键词

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