Terrestrial methane cycle perturbations during the onset of the Paleocene-Eocene Thermal Maximum
Terrestrial methane cycle perturbations during the onset of the Paleocene-Eocene Thermal Maximum
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DOI：
10.1130/g48110.1
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发表时间：
2021-05-01
期刊：
影响因子：
5.8
通讯作者：
Pancost, Richard D.
中科院分区：
文献类型：
--
作者：
Inglis, Gordon N.;Rohrssen, Megan;Pancost, Richard D.
陆地甲烷（CH 4）排放量可能在古新世-始新世热最大期（PETM;约。56 Ma），并促进了额外的变暖，特别是在高纬度地区。虽然有证据表明，在一个单一的北方半球的网站增加甲烷循环，是否增强甲烷循环是全球广泛的是未知的，因为没有随后的调查。甲烷释放的机制也是未知的，因为温度和甲烷循环之间的直接比较迄今为止还不可能。在这里，我们使用生物标志物来重建温度变化和CH 4循环在一个新的PETM年龄的继承在新西兰。我们的研究结果表明，稳定的碳同位素组成（Δ C-13）的细菌hopanoids下降到非常低的值（~ 60份每千）在PETM的开始，表明增加消费的CH 4。这些值远低于发现在现代湿地，并建议一个重大的扰动的甲烷循环在PETM的发病。低hopanoid三角洲C-13值不坚持到始新世早期，尽管有证据表明温度升高。这表明，陆地甲烷循环的运作方式不同，在瞬态相比，逐渐变暖的事件。PETM期间CH 4循环的增强可能有助于解决高纬度地区温度数据-模型不匹配的问题，并可能产生比仅从CO2中获得的地球系统敏感性更高的估计。
Terrestrial methane (CH4) emissions may have increased during the Paleocene-Eocene Thermal Maximum (PETM; ca. 56 Ma) and promoted additional warming, especially in the high latitudes. Although there is evidence for increased CH4 cycling in a single Northern Hemisphere site, whether enhanced methane cycling was globally widespread is unknown because there have been no subsequent investigations. The mechanism of CH4 release is also unknown because a direct comparison between temperature and CH4 cycling has so far not been possible. Here we use biomarkers to reconstruct temperature change and CH4 cycling in a new PETM-aged succession in New Zealand. Our results indicate that the stable carbon isotopic composition (delta C-13) of bacterial hopanoids decreased to very low values (-60 parts per thousand) during the onset of the PETM, indicating enhanced consumption of CH4. These values are much lower than found in modern wetlands and suggest a major perturbation of the CH4 cycle during the onset of the PETM. Low hopanoid delta C-13 values do not persist into the early Eocene, despite evidence for elevated temperatures. This indicates that the terrestrial CH4 cycle operates differently during transient compared to gradual warming events. Enhanced CH4 cycling during the PETM may help to resolve the temperature data-model mismatch in the high latitudes and could yield higher estimates of Earth system sensitivity than expected from CO2 alone.