Glacial cooling and climate sensitivity revisited
Glacial cooling and climate sensitivity revisited
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DOI：
10.1038/s41586-020-2617-x
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发表时间：
2020-08-27
期刊：
影响因子：
64.8
通讯作者：
Poulsen, Christopher J.
中科院分区：
文献类型：
--
作者：
Tierney, Jessica E.;Zhu, Jiang;Poulsen, Christopher J.
末次盛冰期（LGM）是研究得最好的古气候间隔之一，为研究气候系统如何响应温室气体和冰冻圈的变化提供了绝佳的机会。以前的工作试图限制从古温度计（1，2）冰川冷却的幅度和模式，但代理的不均匀分布，以及他们的不确定性，挑战了LGM气候状态的全视野的建设。在这里，我们结合联合收割机的海洋表面温度与同位素启用气候模型合奏地球化学代理的大集合，产生一个现场重建末次冰期温度使用数据同化。重建验证扣留代理以及独立的冰芯和洞穴三角洲O-18测量。我们的同化产品对全球平均LGM冷却的限制为-6.1摄氏度（95%置信区间：-6.5至-5.7摄氏度）。考虑到温室气体、冰盖和矿物尘埃气溶胶的辐射强迫，这种冷却转化为3.4摄氏度的平衡气候敏感性（2.4-4.5摄氏度），这一数值高于之前基于LGM的估计，但与传统的共识范围2-4.5摄氏度一致（3，4）使用代用数据汇编和同位素气候模式集合来限制末次冰盛期的冷却，产生与目前共识范围一致的平衡气候敏感性估计。
The Last Glacial Maximum (LGM), one of the best studied palaeoclimatic intervals, offers an excellent opportunity to investigate how the climate system responds to changes in greenhouse gases and the cryosphere. Previous work has sought to constrain the magnitude and pattern of glacial cooling from palaeothermometers(1,2), but the uneven distribution of the proxies, as well as their uncertainties, has challenged the construction of a full-field view of the LGM climate state. Here we combine a large collection of geochemical proxies for sea surface temperature with an isotope-enabled climate model ensemble to produce a field reconstruction of LGM temperatures using data assimilation. The reconstruction is validated with withheld proxies as well as independent ice core and speleothem delta O-18 measurements. Our assimilated product provides a constraint on global mean LGM cooling of -6.1 degrees Celsius (95 per cent confidence interval: -6.5 to -5.7 degrees Celsius). Given assumptions concerning the radiative forcing of greenhouse gases, ice sheets and mineral dust aerosols, this cooling translates to an equilibrium climate sensitivity of 3.4 degrees Celsius (2.4-4.5 degrees Celsius), a value that is higher than previous LGM-based estimates but consistent with the traditional consensus range of 2-4.5 degrees Celsius(3,4).A compilation of proxy data are used with an isotope-enabled climate model ensemble to constrain cooling during the Last Glacial Maximum, producing estimates of equilibrium climate sensitivity that agree well with the current consensus range.