On the causes of mid-Pliocene warmth and polar amplification
On the causes of mid-Pliocene warmth and polar amplification
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DOI：
10.1016/j.epsl.2011.12.042
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发表时间：
2012-03-01
影响因子：
5.3
通讯作者：
Loptson, Claire A.
中科院分区：
文献类型：
--
作者：
Lunt, Daniel J.;Haywood, Alan M.;Loptson, Claire A.
上新世中期（近似3 ~ 3.3 Ma前）是一个与第四纪晚期（0 ~近似1 Ma前）相比持续全球变暖的时期，有可能为未来长期气候变化的预测提供信息。然而，考虑到几个过程可能起了作用，人们对观测到的温暖或相关的极性放大的原因了解得相对较少。在这里，使用建模方法和一种新的因子分解方法，我们评估的相对贡献上新世中期温暖：升高的二氧化碳，降低地形，植被和冰盖的变化。结果表明，在全球范围内，上新世中期变暖的最大贡献者是CO2浓度升高。然而，在极地放大方面，冰盖的变化在南半球有很大的贡献，而地形的变化在北方半球有很大的贡献。我们还进行了能量平衡分析，表明在全球范围内，地面辐射和大气辐射的变化主导了云的变化。我们调查我们的结果的敏感性，在规定的二氧化碳和地形变化的不确定性，推导出各种贡献过程的不确定性范围。(C)2012爱思唯尔有限公司版权所有。
The mid-Pliocene (similar to 3 to 3.3 Ma ago), is a period of sustained global warmth in comparison to the late Quaternary (0 to similar to 1 Ma ago), and has potential to inform predictions of long-term future climate change. However, given that several processes potentially contributed, relatively little is understood about the reasons for the observed warmth, or the associated polar amplification. Here, using a modelling approach and a novel factorisation method, we assess the relative contributions to mid-Pliocene warmth from: elevated CO2, lowered orography, and vegetation and ice sheet changes. The results show that on a global scale, the largest contributor to mid-Pliocene warmth is elevated CO2. However, in terms of polar amplification, changes to ice sheets contribute significantly in the Southern Hemisphere, and orographic changes contribute significantly in the Northern Hemisphere. We also carry out an energy balance analysis which indicates that that on a global scale, surface albedo and atmospheric emmissivity changes dominate over cloud changes. We investigate the sensitivity of our results to uncertainties in the prescribed CO2 and orographic changes, to derive uncertainty ranges for the various contributing processes. (C) 2012 Elsevier B.V. All rights reserved.