A model for orbital pacing of methane hydrate destabilization during the Palaeogene
A model for orbital pacing of methane hydrate destabilization during the Palaeogene
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DOI：
10.1038/ngeo1266
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发表时间：
2011-11-01
影响因子：
18.3
通讯作者：
Haywood, Alan
中科院分区：
文献类型：
--
作者：
Lunt, Daniel J.;Ridgwell, Andy;Haywood, Alan
一系列短暂的全球变暖事件（1，2）发生在古新世晚期和始新世早期，大约5900万至5000万年前。这些事件虽然大小不一，但显然是以轨道周期为节奏的（2-4），并与全球碳循环的大规模扰动有关（5、6）。然而，在这段时间内，轨道日照变化与碳循环之间的因果关系尚未确定。在这里，我们提出了一系列的耦合气候模型模拟表明，轨道引起的海洋环流和中间水温的变化可以触发甲烷水合物的不稳定。然后，我们使用一个简单的阈值模型来表明，在数百万年的全球变暖的进步，结合海洋保持在一个更加停滞的状态的趋势增加，可以解释整个始新世早期的超高温事件的幅度减小和频率增加。我们的工作表明，气候和碳循环之间的非线性相互作用可以调节轨道变化的影响，在这种情况下，产生不同时间和幅度的短暂全球变暖事件。
A series of transient global warming events(1,2) occurred during the late Palaeocene and early Eocene, about 59 to 50 million years ago. The events, although variable in magnitude, were apparently paced by orbital cycles(2-4) and linked to massive perturbations of the global carbon cycle(5,6). However, a causal link between orbital changes in insolation and the carbon cycle has yet to be established for this time period. Here we present a series of coupled climate model simulations that demonstrate that orbitally induced changes in ocean circulation and intermediate water temperature can trigger the destabilization of methane hydrates. We then use a simple threshold model to show that progressive global warming over millions of years, in combination with the increasing tendency of the ocean to remain in a more stagnant state, can explain the decreasing magnitude and increasing frequency of hyperthermal events throughout the early Eocene. Our work shows that nonlinear interactions between climate and the carbon cycle can modulate the effect of orbital variations, in this case producing transient global warming events with varying timing and magnitude.