Rainfall and drought in equatorial east Africa during the past 1,100 years
Rainfall and drought in equatorial east Africa during the past 1,100 years
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DOI：
10.1038/35000179
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发表时间：
2000-01
期刊：
影响因子：
64.8
通讯作者：
D. Verschuren;K. Laird;B. Cumming
中科院分区：
文献类型：
--
作者：
D. Verschuren;K. Laird;B. Cumming
了解自然降雨量的长期变化对世界亚湿润地区的水资源和土地使用管理至关重要。在非洲热带地区，由于缺乏长期的仪器气候记录，以及树轮和冰芯等标准高分辨率代用记录的潜力有限，与确定这种变率有关的数据很少。在这里，我们提出了一个十年尺度的重建在赤道东非在过去的1,100年中，根据奈瓦沙湖（肯尼亚）的湖泊水位和盐度波动推断从三个不同的古湖泊代理：沉积物地层和化石硅藻和蠓组合的物种组成。我们的数据表明，在过去的一千年中，赤道东非的气候条件之间交替变化，在“中世纪温暖期”（1000 -1270年）和“小冰河期”（1270 -1850年）期间，气候相对潮湿，气候比今天明显干燥，被三次长期干旱打断。我们还发现，重建的自然长期降雨量变化的历史和东非的前殖民文化史之间的时间关系很强，突出了详细了解自然长期降雨量波动对可持续社会经济发展的重要性。
Knowledge of natural long-term rainfall variability is essential for water-resource and land-use management in sub-humid regions of the world. In tropical Africa, data relevant to determining this variability are scarce because of the lack of long instrumental climate records and the limited potential of standard high-resolution proxy records such as tree rings and ice cores,,. Here we present a decade-scale reconstruction of rainfall and drought in equatorial east Africa over the past 1,100 years, based on lake-level and salinity fluctuations of Lake Naivasha (Kenya) inferred from three different palaeolimnological proxies: sediment stratigraphy and the species compositions of fossil diatom and midge assemblages. Our data indicate that, over the past millennium, equatorial east Africa has alternated between contrasting climate conditions, with significantly drier climate than today during the ‘Medieval Warm Period’ (∼ad1000–1270) and a relatively wet climate during the ‘Little Ice Age’ (∼ad1270–1850) which was interrupted by three prolonged dry episodes. We also find strong chronological links between the reconstructed history of natural long-term rainfall variation and the pre-colonial cultural history of east Africa, highlighting the importance of a detailed knowledge of natural long-term rainfall fluctuations for sustainable socio-economic development.