Last interglacial temperature evolution - a model inter-comparison
Last interglacial temperature evolution - a model inter-comparison
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DOI：
10.5194/cp-9-605-2013
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发表时间：
2013-01-01
影响因子：
4.3
通讯作者：
Schulz, M.
中科院分区：
文献类型：
--
作者：
Bakker, P.;Stone, E. J.;Schulz, M.
基于代理的重建数量不断增加，这些重建详细描述了末次间冰期（LIG）期间发生的气候变化。这个时期特别引人关注，因为全球大部分地区的气候比现在温暖，鉴于预计的全球变暖情况，这一时期成为气候模型的一个有趣的试验场。然而，主要由于同步不同的古气候记录很困难，对于LIG温度变化的全球图景并没有达成共识。在此，我们展示了首次涵盖LIG时期的瞬态模拟的模型间比较。通过比较不同的模拟，我们旨在研究LIG温度演化中的共同信号，探究其背后的主要驱动力，并列出导致模型间差异最明显的气候反馈。模型间比较显示出北半球7月温度演化具有稳健性，其特征是在130 - 125千年BP之间达到最大值，温度比现今高0.3到5.3K。只有当包含温室气体浓度变化时，才会发现南半球7月温度在128千年BP左右达到最大值，为 -1.3到2.5K。模拟的1月温度在南半球以及北半球中纬度地区具有较强的稳健性。对于这些地区，在121千年BP之后的时期，模拟出的1月温度最大异常分别为 -1到1.2K和 -0.8到2.1K。在两个半球，这些温度最大值都与当地夏季太阳辐射的最大值相符。在一些特定区域，在模型之间没有发现共同的温度演化。我们表明这与气候系统内的反馈有关，这些反馈在很大程度上决定了这些区域模拟的LIG温度演化。首先，在北极地区，夏季海冰覆盖的变化控制着LIG冬季温度的演化。其次，对于大西洋地区、南大洋和北太平洋，大西洋经向翻转环流特征的可能变化至关重要。第三，先前冰川期残留的大陆冰的存在在确定北半球LIG最暖时期的时间方面已被证明是重要的。最后，结果显示季风状况的变化对非洲和印度部分地区的LIG温度演化有很强的控制作用。通过列出这些模型间的差异，我们为未来的代理数据研究以及约束气候模拟和进一步增进我们对LIG时期温度演化理解所需的敏感性实验提供了一个起点。
There is a growing number of proxy-based reconstructions detailing the climatic changes that occurred during the last interglacial period (LIG). This period is of special interest, because large parts of the globe were characterized by a warmer-than-present-day climate, making this period an interesting test bed for climate models in light of projected global warming. However, mainly because synchronizing the different palaeoclimatic records is difficult, there is no consensus on a global picture of LIG temperature changes. Here we present the first model inter-comparison of transient simulations covering the LIG period. By comparing the different simulations, we aim at investigating the common signal in the LIG temperature evolution, investigating the main driving forces behind it and at listing the climate feedbacks which cause the most apparent inter-model differences.The model inter-comparison shows a robust Northern Hemisphere July temperature evolution characterized by a maximum between 130-125 ka BP with temperatures 0.3 to 5.3K above present day. A Southern Hemisphere July temperature maximum, -1.3 to 2.5K at around 128 ka BP, is only found when changes in the greenhouse gas concentrations are included. The robustness of simulated January temperatures is large in the Southern Hemisphere and the mid-latitudes of the Northern Hemisphere. For these regions maximum January temperature anomalies of respectively -1 to 1.2K and -0.8 to 2.1K are simulated for the period after 121 ka BP. In both hemispheres these temperature maxima are in line with the maximum in local summer insolation.In a number of specific regions, a common temperature evolution is not found amongst the models. We show that this is related to feedbacks within the climate system which largely determine the simulated LIG temperature evolution in these regions. Firstly, in the Arctic region, changes in the summer sea-ice cover control the evolution of LIG winter temperatures. Secondly, for the Atlantic region, the Southern Ocean and the North Pacific, possible changes in the characteristics of the Atlantic meridional overturning circulation are crucial. Thirdly, the presence of remnant continental ice from the preceding glacial has shown to be important when determining the timing of maximum LIG warmth in the Northern Hemisphere. Finally, the results reveal that changes in the monsoon regime exert a strong control on the evolution of LIG temperatures over parts of Africa and India. By listing these inter-model differences, we provide a starting point for future proxy-data studies and the sensitivity experiments needed to constrain the climate simulations and to further enhance our understanding of the temperature evolution of the LIG period.