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Late Holocene methane rise caused by orbitally controlled increase in tropical sources

机译：热带源的轨道控制增加导致晚新世甲烷上升

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摘要

Considerable debate surrounds the source of the apparently 'anomalous' increase of atmospheric methane concentrations since the mid-Holocene (5,000 years ago) compared to previous interglacial periods as recorded in polar ice core records. Proposed mechanisms for the rise in methane concentrations relate either to methane emissions from anthropogenic early rice cultivation or an increase in natural wetland emissions from tropical or boreal sources. Here we show that our climate and wetland simulations of the global methane cycle over the last glacial cycle (the past 130,000 years) recreate the ice core record and capture the late Holocene increase in methane concentrations. Our analyses indicate that the late Holocene increase results from natural changes in the Earth's orbital configuration, with enhanced emissions in the Southern Hemisphere tropics linked to precession-induced modi-fication of seasonal precipitation. Critically, our simulations capture the declining trend in methane concentrations at the end of the last interglacial period (115,000-130,000 years ago) that was used to diagnose the Holocene methane rise as unique. The difference between the two time periods results from differences in the size and rate of regional insolation changes and the lack of glacial incep-tion in the Holocene. Our findings also suggest that no early agri-cultural sources are required to account for the increase in methane concentrations in the 5,000 years before the industrial era.
机译：自从全新世中期（5000年前）以来，与极地冰芯记录中记录的先前冰期之间相比，大气甲烷浓度明显“异常”增加的原因围绕着很大的争议。甲烷浓度升高的拟议机制与人为早稻栽培中甲烷排放量或热带或北方来源的自然湿地排放量增加有关。在这里，我们显示了我们对最后一个冰川周期（过去130,000年）中全球甲烷循环的气候和湿地模拟，重新建立了冰芯记录并捕获了全新世晚期甲烷浓度的增加。我们的分析表明，全新世晚期的增加是地球轨道结构的自然变化造成的，南半球热带地区的排放增加与岁差引起的季节性降水的修正有关。至关重要的是，我们的模拟捕获了在最后一个冰期间期（115,000-130,000年前）结束时甲烷浓度下降的趋势，这被用来诊断全新世甲烷的升高。这两个时间段之间的差异是由于区域日照变化的大小和速率不同以及全新世缺乏冰期侵入所致。我们的发现还表明，在工业时代之前的5,000年中，不需要早期的农业资源就可以解释甲烷浓度的增加。

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  • 来源
    《Nature》 |2011年第7332期|p.82-85|共4页
  • 作者

    Joy S. Singarayer; Paul J. Valdes; Pierre Friedlingstein; Sarah Nelson; David J. Beerling;

  • 作者单位

    Bristol Research Initiative for the Dynamic Global Environment, School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UK;

    Bristol Research Initiative for the Dynamic Global Environment, School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UK;

    Bristol Research Initiative for the Dynamic Global Environment, School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UK,College of Engineering, Mathematics and Physical Sciences, University of Exeter, Harrison Building, North Park Road, Exeter EX4 4QF, UK;

    Bristol Research Initiative for the Dynamic Global Environment, School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UK;

    Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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