Understanding the glacial methane cycle.
Understanding the glacial methane cycle.
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DOI：
10.1038/ncomms14383
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发表时间：
2017-02-21
影响因子：
16.6
通讯作者：
Beerling DJ
中科院分区：
文献类型：
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作者：
Hopcroft PO;Valdes PJ;O'Connor FM;Kaplan JO;Beerling DJ
大气甲烷（CH 4）随第四纪气候变化而变化，从21，000年前末次盛冰期（LGM）的375 p. p. b. v.上升到工业革命开始时的680 p. p. b. v.。然而，这种增加的原因仍然不清楚;提出的假设依赖于CH 4源或CH 4大气寿命或两者的波动。在这里，我们使用一个地球系统模型来提供一个全面的评估，这些竞争的假设，包括估计的不确定性。我们发现，在这个模型中，全球LGM CH 4源减少了2 - 8 - 46%，寿命增加了2- 8%，最佳估计LGM CH 4浓度为463-480 p. p. b. v.模拟观测到的LGM浓度需要减少46-49%的来源，这表明我们不能调和观测到的幅度。这突出表明，需要更好地了解低CO2和较冷气候对湿地和其他天然CH 4源的影响。大气中甲烷含量从最后一个冰河时期的375 p. p. b. v.增加到工业化初期的680 p. p. b. v.的原因仍然不确定。在这里，使用地球系统模型，作者表明，我们不能根据我们目前对天然甲烷来源的理解来调和这种上升。
Atmospheric methane (CH4) varied with climate during the Quaternary, rising from a concentration of 375 p.p.b.v. during the last glacial maximum (LGM) 21,000 years ago, to 680 p.p.b.v. at the beginning of the industrial revolution. However, the causes of this increase remain unclear; proposed hypotheses rely on fluctuations in either the magnitude of CH4 sources or CH4 atmospheric lifetime, or both. Here we use an Earth System model to provide a comprehensive assessment of these competing hypotheses, including estimates of uncertainty. We show that in this model, the global LGM CH4 source was reduced by 28–46%, and the lifetime increased by 2–8%, with a best-estimate LGM CH4 concentration of 463–480 p.p.b.v. Simulating the observed LGM concentration requires a 46–49% reduction in sources, indicating that we cannot reconcile the observed amplitude. This highlights the need for better understanding of the effects of low CO2 and cooler climate on wetlands and other natural CH4 sources. The cause of the increase in atmospheric methane from 375 p.p.b.v. during the last ice age to 680 p.p.b.v. at the onset of Industrialization remains uncertain. Here, using an Earth system model, the authors show that we cannot reconcile this rise based on our current understanding of natural methane sources.