Atmospheric methane variability through the Last Glacial Maximum and deglaciation mainly controlled by tropical sources
Atmospheric methane variability through the Last Glacial Maximum and deglaciation mainly controlled by tropical sources
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DOI：
10.1038/s41561-023-01332-x
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发表时间：
2023-11
影响因子：
18.3
通讯作者：
Ben Riddell-Young;J. Rosen;Edward Brook;C. Buizert;Kaden Martin;James E. Lee;J. Edwards;
中科院分区：
文献类型：
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作者：
Ben Riddell-Young;J. Rosen;Edward Brook;C. Buizert;Kaden Martin;James E. Lee;J. Edwards;
限制过去大气甲烷变化的原因对于理解甲烷和气候之间的联系非常重要。在最后一次冰消期甲烷的突然变化已经为此目的进行了深入的研究，但高纬度和热带来源的相对重要性仍然没有得到充分的限制。甲烷极间浓度差异反映了过去的地理排放变化，但现有的记录遭受微妙的，但相当大的甲烷生产在分析期间。在这里，我们报告了一个冰芯衍生的极间差异记录，涵盖了末次冰期最大和冰川消退，大大提高了时间分辨率，年表和关键的校正来自格陵兰岛的样品中的甲烷生产。使用箱模型来推断纬向源的变化，我们表明，热带源占主导地位的突然甲烷变化的冰消期，突出了他们的敏感性，突然的气候变化和迅速转变的热带降雨模式。北方的大气外排放在约16，000年前开始增加，可能是由于高纬度变暖引起的湿地扩张和/或永久冻土退化，并对甲烷突然上升的贡献最多为25 Tg yr−1（占总排放量增加的45%），这与博林-阿勒罗德间隔开始时北方迅速变暖相吻合。这些制约冰川消退的气候甲烷循环的相互作用，可以提高理解可能的现在和未来的反馈。
Constraining the causes of past atmospheric methane variability is important for understanding links between methane and climate. Abrupt methane changes during the last deglaciation have been intensely studied for this purpose, but the relative importance of high-latitude and tropical sources remains poorly constrained. The methane interpolar concentration difference reflects past geographic emission variability, but existing records suffered from subtle but considerable methane production during analysis. Here, we report an ice-core-derived interpolar difference record covering the Last Glacial Maximum and deglaciation, with substantially improved temporal resolution, chronology and a critical correction for methane production in samples from Greenland. Using box models to infer latitudinal source changes, we show that tropical sources dominated abrupt methane variability of the deglaciation, highlighting their sensitivity to abrupt climate change and rapidly shifting tropical rainfall patterns. Northern extratropical emissions began increasing ~16,000 years ago, probably through wetland expansion and/or permafrost degradation induced by high-latitude warming, and contributed at most 25 Tg yr−1(45% of the total emission increase) to the abrupt methane rise that coincided with rapid northern warming at the onset of the Bølling–Allerød interval. These constraints on deglacial climate–methane cycle interactions can improve the understanding of possible present and future feedbacks.