Late Miocene cooling coupled to carbon dioxide with Pleistocene-like climate sensitivity
Late Miocene cooling coupled to carbon dioxide with Pleistocene-like climate sensitivity
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DOI：
10.1038/s41561-022-00982-7
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发表时间：
2022-07-25
影响因子：
18.3
通讯作者：
Foster, Gavin L.
中科院分区：
文献类型：
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作者：
Brown, Rachel M.;Chalk, Thomas B.;Foster, Gavin L.
在1200万至500万年前的中新世晚期，地球气候明显变冷，对全球生态系统产生了深远的影响。然而，这些变化的驱动力仍然存在争议。取得进展的一个主要障碍是温室气体辐射强迫作用的不确定性。在这里，我们提出的硼同位素组成的南极有孔虫，记录二氧化碳变化的最快速冷却的时间间隔，晚中新世冷却事件之间的7和5马。我们的记录表明，在这200万年的时间间隔内，CO2下降了约100 ppm，在大约5.9 Ma时达到最低值。考虑到非CO2温室气体和缓慢的气候反馈，我们估计全球平均表面温度变化的CO2平衡气候敏感性的两倍为3.9摄氏度（1.8-6.7摄氏度，95%的置信度）的基础上比较我们的记录的辐射强迫从CO2与全球平均表面温度变化的记录。结果表明，晚中新世的CO2变化与气候变化密切相关，晚更新世、新生代其他时间段和21世纪的平衡气候敏感性均在政府间气候变化专门委员会的估计范围内，晚中新世的气候敏感性与晚更新世和21世纪相当。根据南极有孔虫中硼同位素测定的二氧化碳记录，
Earth's climate cooled markedly during the late Miocene from 12 to 5 million years ago, with far-reaching consequences for global ecosystems. However, the driving forces of these changes remain controversial. A major obstacle to progress is the uncertainty over the role played by greenhouse gas radiative forcing. Here we present boron isotope compositions for planktic foraminifera, which record carbon dioxide change for the interval of most rapid cooling, the late Miocene cooling event between 7 and 5 Ma. Our record suggests that CO2 declined by some 100 ppm over this two-million-year-long interval to a minimum at approximately 5.9 Ma. Having accounted for non-CO2 greenhouse gasses and slow climate feedbacks, we estimate global mean surface temperature change for a doubling of CO2-equilibrium climate sensitivity-to be 3.9 degrees C (1.8-6.7 degrees C at 95% confidence) on the basis of comparison of our record of radiative forcing from CO2 with a record of global mean surface temperature change. We conclude that changes in CO2 and climate were closely coupled during the latest Miocene and that equilibrium climate sensitivity was within range of estimates for the late Pleistocene, other intervals of the Cenozoic and the twenty-first century as presented by the Intergovernmental Panel on Climate Change.Climate sensitivity in the late Miocene was comparable to the late Pleistocene and twenty-first century, with cooling at the time coupled to declining carbon dioxide, according to a CO2 record determined from boron isotopes in planktic foraminifera