Molecular records of climate variability and vegetation response since the Late Pleistocene in the Lake Victoria basin, East Africa
Molecular records of climate variability and vegetation response since the Late Pleistocene in the Lake Victoria basin, East Africa
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DOI：
10.1016/j.quascirev.2012.08.014
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发表时间：
2012-11-08
影响因子：
4
通讯作者：
Damste, Jaap S. Sinninghe
中科院分区：
文献类型：
--
作者：
Berke, Melissa A.;Johnson, Thomas C.;Damste, Jaap S. Sinninghe
新的分子温度和水文代理有助于限制热带气候变化和阐明可能的强迫机制在全新世。在这里，我们研究了东非维多利亚湖14,000年来气候变化的类似记录，维多利亚湖是世界上表面积第二大的淡水湖。我们确定了当地水文气候的变化，使用化合物特定的三角洲D的陆地叶蜡，并比较这些结果的温度利用TEX 86古温度代理的新记录，基于水生Thaumarchaeotal膜脂。为了评估气候变化对陆地环境的影响，我们产生了一个记录的化合物特定三角洲C-13从陆地叶蜡，生态系统水平的C-3/C-4植物丰度的代理，并比较结果与以前发表的花粉推断的区域植被变化。我们观察到温度和降雨之间的一般一致性，温暖，潮湿的间隔峰值类似于10-9 ka，随后逐渐冷却和干燥的全新世的其余部分。这些结果，特别是降雨量的结果，与其他热带非洲气候记录基本一致，表明对热带东非广大地区气候的看法在某种程度上是一致的。来自维多利亚湖叶蜡的δ C-13记录似乎并不能反映区域气候或植被的变化。然而，孢粉学分析文件突然转变，从禾本科（草）为主的生态系统在寒冷，干旱的晚更新世，以Moraceae为主（树木/灌木）的景观在温暖，潮湿的全新世早期。我们的理论是，这些代理反映植被在不同的位置周围的维多利亚湖。我们的研究结果表明，主要是日照强迫气候，温暖，潮湿的条件下达到峰值，在最大的半球间的季节性日照对比度，可能会加强季风降水，而最大的干燥度与雨季日照和半球间的对比度梯度最小值相吻合。我们解释在新仙女木气候条件的转变，以表明有限的开关在日照主导的控制气候的维多利亚湖地区，远程遥相关与耦合的大西洋和太平洋气候系统。2012爱思唯尔有限公司保留所有权利。
New molecular proxies of temperature and hydrology are helping to constrain tropical climate change and elucidate possible forcing mechanisms during the Holocene. Here, we examine a similar to 14,000 year record of climate variability from Lake Victoria, East Africa, the world's second largest freshwater lake by surface area. We determined variations in local hydroclimate using compound specific delta D of terrestrial leaf waxes, and compared these results to a new record of temperature utilizing the TEX86 paleo-temperature proxy, based on aquatic Thaumarchaeotal membrane lipids. In order to assess the impact of changing climate on the terrestrial environment, we generated a record of compound specific delta C-13 from terrestrial leaf waxes, a proxy for ecosystem-level C-3/C-4 plant abundances, and compared the results to previously published pollen-inferred regional vegetation shifts. We observe a general coherence between temperature and rainfall, with a warm, wet interval peaking similar to 10-9 ka and subsequent gradual cooling and drying over the remainder of the Holocene. These results, particularly those of rainfall, are in general agreement with other tropical African climate records, indicating a somewhat consistent view of climate over a wide region of tropical East Africa. The delta C-13 record from Lake Victoria leaf waxes does not appear to reflect changes in regional climate or vegetation. However, palynological analyses document an abrupt shift from a Poaceae (grasses)-dominated ecosystem during the cooler, arid late Pleistocene to a Moraceae-dominated (trees/shrubs) landscape during the warm, wet early Holocene. We theorize that these proxies are reflecting vegetation in different locations around lake Victoria. Our results suggest a predominantly insolation-forced climate, with warm, wet conditions peaking at the maximum interhemispheric seasonal insolation contrast, likely intensifying monsoonal precipitation, while maximum aridity coincides with the rainy season insolation and the interhemispheric contrast gradient minima. We interpret a shift in conditions at the Younger Dryas to indicate a limited switch in insolation-dominated control on climate of the Lake Victoria region, to remote teleconnections with the coupled Atlantic and Pacific climate system. 2012 Elsevier Ltd. All rights reserved.