Evaluating the dominant components of warming in Pliocene climate simulations
Evaluating the dominant components of warming in Pliocene climate simulations
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DOI：
10.5194/cp-10-79-2014
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发表时间：
2014-01-01
影响因子：
4.3
通讯作者：
Ueda, H.
中科院分区：
文献类型：
--
作者：
Hill, D. J.;Haywood, A. M.;Ueda, H.
上新世模式比较项目（PlioMIP）是第一个协调的气候模式比较，比较了大气CO2浓度显著高于工业化前的更温暖的古气候。上新世中期暖期的模拟显示，全球变暖幅度比工业化前的地表气温高1.8至3.6摄氏度，并伴有显著的极性放大。在这里，我们对PlioMIP实验2中所有8个耦合的海洋-大气模拟进行能量平衡计算，以评估温度升高的原因和模式之间的差异。在热带地区，模拟的变暖主要是温室气体的增加，在大多数模式中，行星反照率的云成分增强了变暖，但量差异很大。不同的气候模式对北半球中纬度地区上新世中期气候强迫的响应有很大不同，唯一一致的响应是温室气体增加导致的变暖。在高纬度地区，所有能量平衡分量都变得重要，但主要的增温影响来自晴空反照率，仅部分被云反照率的增温影响所抵消。这说明了特定冰盖和高纬度植被边界条件以及模拟海冰和积雪反照率反馈的重要性。总体不确定性中最大的分量与热带云和极地晴空反照率有关，特别是在海冰区。这些模拟表明，反照率反馈，特别是海冰和冰盖的反照率反馈，对上新世高纬度变暖提供了最显著的增强。
The Pliocene Model Intercomparison Project (PlioMIP) is the first coordinated climate model comparison for a warmer palaeoclimate with atmospheric CO2 significantly higher than pre-industrial concentrations. The simulations of the mid-Pliocene warm period show global warming of between 1.8 and 3.6 degrees C above pre-industrial surface air temperatures, with significant polar amplification. Here we perform energy balance calculations on all eight of the coupled ocean-atmosphere simulations within PlioMIP Experiment 2 to evaluate the causes of the increased temperatures and differences between the models. In the tropics simulated warming is dominated by greenhouse gas increases, with the cloud component of planetary albedo enhancing the warming in most of the models, but by widely varying amounts. The responses to mid-Pliocene climate forcing in the Northern Hemisphere midlatitudes are substantially different between the climate models, with the only consistent response being a warming due to increased greenhouse gases. In the high latitudes all the energy balance components become important, but the dominant warming influence comes from the clear sky albedo, only partially offset by the increases in the cooling impact of cloud albedo. This demonstrates the importance of specified ice sheet and high latitude vegetation boundary conditions and simulated sea ice and snow albedo feedbacks. The largest components in the overall uncertainty are associated with clouds in the tropics and polar clear sky albedo, particularly in sea ice regions. These simulations show that albedo feedbacks, particularly those of sea ice and ice sheets, provide the most significant enhancements to high latitude warming in the Pliocene.