CO2-driven ocean circulation changes as an amplifier of Paleocene-Eocene thermal maximum hydrate destabilization
CO2-driven ocean circulation changes as an amplifier of Paleocene-Eocene thermal maximum hydrate destabilization
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DOI：
10.1130/g31184.1
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发表时间：
2010-10
期刊：
影响因子：
5.8
通讯作者：
D. Lunt;P. Valdes;T. Jones;A. Ridgwell;A. Haywood;D. Schmidt;R. Marsh;M. Maslin
中科院分区：
文献类型：
--
作者：
D. Lunt;P. Valdes;T. Jones;A. Ridgwell;A. Haywood;D. Schmidt;R. Marsh;M. Maslin
海洋环流的变化被认为是古新世-始新世热极大期（PETM，ca. 55Ma）。海洋中层沃茨的突然变暖可能引发沉积物中的甲烷水合物的热不稳定，并可能引发沉积物滑塌和滑坡。在一个完全耦合的大气-海洋环流模式（AOGCM）模拟的晚古新世和早始新世的合奏，我们确定了这样一个循环驱动的增强中层水变暖。至关重要的是，我们发现，当二氧化碳水平从2倍增加到4倍时，大西洋中层水变暖的放大率大约是从1倍增加到2倍时的两倍。这种变暖主要集中在赤道和南大西洋，并由南大洋深水形成的显着减少所驱动。这种情况是一致的，从海底碳同位素数据和强度的深海碳酸盐溶解在南大西洋推断改变PETM循环模式。中层水变暖和天然气水合物不稳定之间的联系可以提供一个重要的反馈，在建立高峰期温暖。
Changes in ocean circulation have been proposed as a trigger mechanism for the large coupled climate and carbon cycle perturbations at the Paleocene-Eocene Thermal Maximum (PETM, ca. 55 Ma). An abrupt warming of oceanic intermediate waters could have initiated the thermal destabilization of sediment-hosted methane gas hydrates and potentially triggered sediment slumps and slides. In an ensemble of fully coupled atmosphere-ocean general circulation model (AOGCM) simulations of the late Paleocene and early Eocene, we identify such a circulation-driven enhanced intermediate-water warming. Critically, we find an approximate twofold amplification of Atlantic intermediate-water warming when CO2 levels are doubled from 2x to 4x preindustrial CO2 compared to when they are doubled from 1x to 2x. This warming is largely focused on the equatorial and South Atlantic and is driven by a significant reduction in deep-water formation from the Southern Ocean. This scenario is consistent with altered PETM circulation patterns inferred from benthic carbon isotope data and the intensity of deep-sea carbonate dissolution in the South Atlantic. The linkage between intermediate-water warming and gas hydrate destabilization could provide an important feedback in the establishment of peak PETM warmth.