Earth's radiative imbalance from the Last Glacial Maximum to the present
Earth's radiative imbalance from the Last Glacial Maximum to the present
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DOI：
10.1073/pnas.1905447116
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发表时间：
2019-07-23
影响因子：
11.1
通讯作者：
Fischer, Hubertus
中科院分区：
文献类型：
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作者：
Baggenstos, Daniel;Haberli, Marcel;Fischer, Hubertus
大气层顶部的能量不平衡决定了全球气候的时间演变，反之亦然，气候系统的变化可以改变行星能量通量。这种相互作用对于我们理解地球的热量收支和气候系统至关重要。然而，即使在今天，直接测量全球辐射通量仍然很困难，因此大多数评估都是基于气候系统总能量含量的变化。我们应用相同的方法来估计过去地球辐射不平衡的长期演变。欧洲冰芯项目对南极洲 Dome C 冰芯过去 4 万年的稀有气体平均海洋温度的新测量，结合西南极冰盖分水岭冰芯和海平面记录的最新结果，使我们能够定量重建气候系统能量预算的历史。该量的时间导数必须等于行星辐射不平衡。在冰消期，典型的+0.2 W.m(-2)的正失衡会维持大约10,000年，然而，在大西洋经向翻转环流大幅减少期间，有两个不同的峰值达到0.4 Wm(-2)。我们的结论是，这些峰值与海洋吸热的净变化有关，可能是由于北大西洋深水形成的快速变化及其对全球辐射平衡的影响，而云覆盖的变化（尽管不确定）也可能是影响因素。
The energy imbalance at the top of the atmosphere determines the temporal evolution of the global climate, and vice versa changes in the climate system can alter the planetary energy fluxes. This interplay is fundamental to our understanding of Earth's heat budget and the climate system. However, even today, the direct measurement of global radiative fluxes is difficult, such that most assessments are based on changes in the total energy content of the climate system. We apply the same approach to estimate the long-term evolution of Earth's radiative imbalance in the past. New measurements of noble gas-derived mean ocean temperature from the European Project for Ice Coring in Antarctica Dome C ice core covering the last 40,000 y, combined with recent results from the West Antarctic Ice Sheet Divide ice core and the sea-level record, allow us to quantitatively reconstruct the history of the climate system energy budget. The temporal derivative of this quantity must be equal to the planetary radiative imbalance. During the deglaciation, a positive imbalance of typically +0.2 W.m(-2) is maintained for similar to 10,000 y, however, with two distinct peaks that reach up to 0.4 Wm(-2) during times of substantially reduced Atlantic Meridional Overturning Circulation. We conclude that these peaks are related to net changes in ocean heat uptake, likely due to rapid changes in North Atlantic deep-water formation and their impact on the global radiative balance, while changes in cloud coverage, albeit uncertain, may also factor into the picture.