Bains S, Norris R D, Corfield R M, Faul K L
Department of Earth Sciences, University of Oxford, UK.
Nature. 2000 Sep 14;407(6801):171-4. doi: 10.1038/35025035.
The onset of the Palaeocene/Eocene thermal maximum (about 55 Myr ago) was marked by global surface temperatures warming by 5-7 degrees C over approximately 30,000 yr (ref. 1), probably because of enhanced mantle outgassing and the pulsed release of approximately 1,500 gigatonnes of methane carbon from decomposing gas-hydrate reservoirs. The aftermath of this rapid, intense and global warming event may be the best example in the geological record of the response of the Earth to high atmospheric carbon dioxide concentrations and high temperatures. This response has been suggested to include an intensified flux of organic carbon from the ocean surface to the deep ocean and its subsequent burial through biogeochemical feedback mechanisms. Here we present firm evidence for this view from two ocean drilling cores, which record the largest accumulation rates of biogenic barium--indicative of export palaeoproductivity--at times of maximum global temperatures and peak excursion values of delta13C. The unusually rapid return of delta13C to values similar to those before the methane release and the apparent coupling of the accumulation rates of biogenic barium to temperature, suggests that the enhanced deposition of organic matter to the deep sea may have efficiently cooled this greenhouse climate by the rapid removal of excess carbon dioxide from the atmosphere.
古新世/始新世极热事件（约5500万年前）开始时，全球地表温度在大约3万年的时间里上升了5 - 7摄氏度（参考文献1），这可能是由于地幔排气增强以及分解的天然气水合物储层中约15000亿吨甲烷碳的脉冲式释放。这一快速、强烈且全球性的变暖事件的后续影响，可能是地质记录中地球对高大气二氧化碳浓度和高温响应的最佳例子。有人认为这种响应包括从海洋表层到深海的有机碳通量增强，以及随后通过生物地球化学反馈机制进行的埋藏。在此，我们从两个海洋钻探岩芯中给出了支持这一观点的确凿证据，这些岩芯记录了在全球温度最高和δ13C峰值偏移时，生物源钡的最大积累速率——这表明了古生产力输出。δ13C异常迅速地恢复到与甲烷释放前相似的值，以及生物源钡积累速率与温度明显的耦合，表明向深海中有机物质沉积的增强可能通过从大气中快速去除过量二氧化碳，有效地冷却了这种温室气候。
