Modern drought conditions in western Sahel unprecedented in the past 1600years
Modern drought conditions in western Sahel unprecedented in the past 1600years
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DOI：
10.1007/s00382-018-4311-3
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发表时间：
2019-02-01
期刊：
影响因子：
4.6
通讯作者：
Wade, Malick
中科院分区：
文献类型：
--
作者：
Carre, Matthieu;Azzoug, Moufok;Wade, Malick
由于气候模型对萨赫勒地区未来降雨量的不确定性仍然很大，需要从百年的角度来评估全球变暖背景下当前萨赫勒地区的气候状况。我们在这里介绍了塞内加尔过去1600年来的第一个水文气候变化的记录，这是从萨鲁姆三角洲考古贝壳中的稳定氧同位素分析(O-18)获得的。在前工业化时期，该地区相对潮湿，在公元1500年至公元1800年期间达到最大湿度，被称为小冰期。在百年尺度上观察到了萨赫勒地区全球温度和湿度之间的显著负联系，这与上个千年期间热带辐合带纬度变化的预期影响不符。在过去1600年的背景下，西萨赫勒地区今天似乎正在经历前所未有的干旱状况。从公元1800年左右开始的快速干旱和最近萨赫勒干旱从自然变化中出现，表明萨赫勒干旱趋势是人为强迫的。这一新的长期观点表明，过去十年萨赫勒降雨量的恢复可能只是短期内部变化的结果，并支持预测未来温室气候下萨赫勒干旱加剧的气候模型。
As climate model uncertainties remain very large for future rainfall in the Sahel, a multi-centennial perspective is required to assess the situation of current Sahel climate in the context of global warming. We present here the first record of hydroclimatic variability over the past 1600years in Senegal, obtained from stable oxygen isotope analyses (O-18) in archaeological shell middens from the Saloum Delta. During the preindustrial period, the region was relatively humid, with maximum humidity reached during the period from AD 1500 to AD 1800, referred to as the Little Ice Age. A significant negative link is observed at the centennial scale between global temperature and humidity in the Sahel that is at odds with the expected effects of latitudinal shifts of the intertropical convergence zone during the last millennium. In the context of the past 1600years, the Western Sahel appears to be experiencing today unprecedented drought conditions. The rapid aridification that started ca. AD 1800 and the recent emergence of Sahel drought from the natural variability point to an anthropogenic forcing of Sahel drying trend. This new long-term perspective suggests that the recovery of Sahel rainfall in the last decade may only result from short-term internal variability, and supports climate models that predict an increase of Sahel drought under future greenhouse climate.