Research press release


Nature Geoscience

Ancient carbon export


Adina Paytanたちは、全球から得られた海洋堆積物を用いて、5600万年前の暁新世~始新世温度極大期の間に海洋表層から取り除かれた炭素の量を見積もった。彼らは海洋中層での炭素の吸収と輸送は温暖化が極大に達した時期に増加したことを見つけた。Paytonたちは、当時の海洋表層水と中層水中での微生物活動の増加により、海洋有機炭素がすぐには消費できない形の化合物へと分解されたと論じている。もしそうならば、炭素は何万年間にもわたり海洋中層水に捕獲され続けたことになる。Paytanたちは、継続した炭素の消費と貯蔵が二酸化炭素を大気から取り除き、惑星をより寒冷な状態へと戻す一助となったと結論づけている。

Some excess carbon released during a period of global warming 56 million years ago may have been removed from the atmosphere by enhanced biological activity in the oceans, according to a paper published online in Nature Geoscience. The enhanced transfer of carbon from the surface ocean to depth may have helped remove carbon dioxide from the atmosphere and thus aided in cooling the climate.

Adina Paytan and colleagues used marine sediment records from around the globe to estimate the amount of carbon that was removed from the surface oceans during the Palaeocene-Eocene Thermal Maximum, about 56 million years ago. They found that carbon uptake and export to the mid-depths of the ocean increased during the interval of peak warmth. The authors argue that increased bacterial activity in the surface waters and mid-depths of the ocean at this time would have broken the marine organic carbon down into compounds that were not readily consumable. If so, carbon would have remained trapped in the waters of the mid-to-deep oceans for tens of thousands of years. Paytan and colleagues conclude that the continued consumption and storage of carbon would have removed carbon dioxide from the atmosphere, and helped return the planet to cooler temperatures.

doi: 10.1038/ngeo2139


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