Climate Sensitivity on Geological Timescales Controlled by Nonlinear Feedbacks and Ocean Circulation
Climate Sensitivity on Geological Timescales Controlled by Nonlinear Feedbacks and Ocean Circulation
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DOI：
10.1029/2019gl083574
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发表时间：
2019-08-28
影响因子：
5.2
通讯作者：
Robinson, S. A.
中科院分区：
文献类型：
--
作者：
Farnsworth, A.;Lunt, D. J.;Robinson, S. A.
气候敏感性是用于评估二氧化碳浓度增加导致的全球变暖程度的一个关键指标。地质学的过去可以提供对气候敏感性的见解;然而，在数百万年的时间尺度上，二氧化碳以外的因素可以驱动气候，包括古地理强迫和太阳光度。在这里，通过覆盖1.5亿至3500万年前的气候模型模拟的集合，我们表明，气候对二氧化碳加倍的敏感性在这段时间内在3.5至5.5摄氏度之间变化。这些变化可以被解释为对太阳光度的非线性响应，由于海洋面积的变化和海洋环流的变化而不断变化的表面张力。这项工作表明，现代气候的敏感性是相对较低的地质记录的背景下，由于相对较弱的反馈，由于相对较低的二氧化碳基线，冰和相对较小的海洋面积在现代大陆配置的存在。
Climate sensitivity is a key metric used to assess the magnitude of global warming given increased CO2 concentrations. The geological past can provide insights into climate sensitivity; however, on timescales of millions of years, factors other than CO2 can drive climate, including paleogeographic forcing and solar luminosity. Here, through an ensemble of climate model simulations covering the period 150-35 million years ago, we show that climate sensitivity to CO2 doubling varies between similar to 3.5 and 5.5 degrees C through this time. These variations can be explained as a nonlinear response to solar luminosity, evolving surface albedo due to changes in ocean area, and changes in ocean circulation. The work shows that the modern climate sensitivity is relatively low in the context of the geological record, as a result of relatively weak feedbacks due to a relatively low CO2 baseline, and the presence of ice and relatively small ocean area in the modern continental configuration.