【人民日报】科学家揭示北极海洋在5600万年前全球变暖中的作用

Core Insights - The research published in the journal "Nature - Earth Science" reveals that changes in ocean sulfate concentrations can alter methane consumption methods, shedding light on the carbon cycle mechanisms behind the extreme global warming and ocean acidification during the Paleocene-Eocene Thermal Maximum (PETM) 56 million years ago [1] Group 1: Research Findings - Approximately 90% of methane in modern oceans is utilized by microorganisms in sediments under anoxic conditions, producing alkaline substances that mitigate ocean acidification [1] - During the PETM, the sulfate concentration in Arctic seawater was less than one-third of modern levels, leading to a shift where oxygen-consuming bacteria began to "rapidly burn" methane, directly consuming oxygen and releasing carbon dioxide [1] - The reconstructed carbon dioxide levels in the Arctic Ocean during the PETM recovery period were 200-700 ppm higher than the global average, indicating a transition from a carbon sink to a carbon source [1] Group 2: Implications for Carbon Cycle - The reduction in sulfate and dilution of seawater forced methane to decompose through "rapid burning," resulting in significant carbon dioxide production [1] - This fundamentally altered the Arctic's role in the global carbon cycle, transforming it from a carbon sink to a greenhouse gas emission source [1]