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首页> 外文学位 >Deciphering arctic climate in a past greenhouse world: Multiproxy reconstructions of pliocene climate.
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Deciphering arctic climate in a past greenhouse world: Multiproxy reconstructions of pliocene climate.

机译：在过去的温室世界中破译北极气候：全新世气候的多代理重建。

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摘要

The high sensitivity of high latitudes to global climate changes is the stimulus for the study of ancient Arctic ecosystems under greenhouse conditions. With an increasing number of studies, including the most recent Intergovernmental Panel on Climate Change (IPCC) report highlighting Pliocene climate as key example for the study of Earth system sensitivity to higher levels of atmospheric CO2, the need for accurate proxy records for this period is crucial.;In order to investigate Pliocene climate, I used stable isotopic studies of fossil molluscs, moss and wood from two fossil forest deposits in the Canadian High Arctic. Temperatures were determined for an Early Pliocene (4-5 Ma) fossil forest site located on Ellesmere Island using 'clumped' and stable isotopic analysis of mollusc shells and stable isotope values of fossil wood. Mollusc inferred growing season (May-Sept) temperatures derived using two independent techniques were estimated to be 11-16°C warmer than present (1950-1990) Ellesmere Island temperatures. Tree ring inferred growing season (June-July) temperatures (JJ) were 10-16°C and mean annual temperatures (MAT) were 18-20°C warmer than present (1950-1990). Mean annual and growing season (JJ) temperatures were also determined using fossil wood from a younger (2.4-2.8 Ma) late Pliocene-early Pleistocene site on Bylot Island. This deposit represents the remains of a flora that grew during an interglacial warm period during the transition to large-scale Northern Hemisphere glaciation that occurred between 2.5 to 3 million years ago. Mean annual temperatures were ∼12° C and growing season temperatures were ∼13°C warmer than present (1923-2010). The interglacial setting of the Bylot Island site and the warm temperatures suggests that prior to using such sites as true analogues of future conditions we may need to consider how close the feedbacks operating then were to the feedbacks we might expect in the future. However, that temperatures so much warmer than present existed in the high Arctic during a period when levels of atmospheric CO2 were at nearpresent levels indicates that we may be moving beyond our ability to use the Pliocene as an example of the future.
机译：高纬度对全球气候变化的高度敏感性是研究温室条件下古代北极生态系统的动力。随着越来越多的研究，包括最新的政府间气候变化专门委员会（IPCC）的报告强调了上新世气候作为研究地球系统对更高水平的大气CO2敏感性的关键示例，该时期需要准确的替代记录为了研究上新世的气候，我使用了来自加拿大高北极地区两个化石森林矿床的化石软体动物，苔藓和木材的稳定同位素研究。使用软体动物壳的“聚集”和稳定同位素分析以及化石的稳定同位素值，确定了位于埃尔斯米尔岛上的上新世（4-5 Ma）化石森林的温度。软体动物推论出的使用两种独立技术得出的生长期（5月至9月）温度估计比当前的Ellesmere岛温度（1950-1990）高11-16°C。年轮（6月至7月）的树环推断温度（JJ）为10-16°C，年平均温度（MAT）比目前的温​​度（1950-1990年）高18-20°C。还使用来自比洛特岛上新世晚期-早更新世晚期的年轻（2.4-2.8 Ma）化石确定了年平均和生长季节（JJ）温度。该沉积物代表了在2.5到300万年前发生的向北半球大规模冰川过渡期间的冰川间温暖期生长的植物群的残留。年平均温度比现在（1923-2010年）高12摄氏度，生长季节温度高13摄氏度。拜洛特岛站点的冰间环境和温暖的温度表明，在将这些站点用作未来条件的真实类似物之前，我们可能需要考虑运行的反馈与我们将来可能期望的反馈有多接近。但是，在大气二氧化碳水平接近当前水平的时期内，北极地区的温度比现在高得多，这表明我们可能已经超出了使用上新世作为未来范例的能力。

著录项

  • 作者

    Csank, Adam Zoltan.;

  • 作者单位

    The University of Arizona.;

  • 授予单位 The University of Arizona.;
  • 学科 Paleoclimate Science.;Geochemistry.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 185 p.
  • 总页数 185
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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