Asymmetric forcing from stratospheric aerosols impacts Sahelian rainfall
Asymmetric forcing from stratospheric aerosols impacts Sahelian rainfall
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DOI：
10.1038/nclimate1857
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发表时间：
2013-07-01
影响因子：
30.7
通讯作者：
Stephenson, David
中科院分区：
文献类型：
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作者：
Haywood, Jim M.;Jones, Andy;Stephenson, David
1970年代至1990年代的萨赫勒干旱是过去50年来最大的人道主义灾难之一，造成多达25万人死亡，并造成1 000万难民（1）。造成这种情况的原因是自然变化（2-5）、过度放牧（6）和工业排放二氧化硫的影响（7、8）。每一种机制都能影响大西洋海面温度梯度，这与萨赫勒地区的降水密切相关（2，3）。我们认为，零星的火山爆发在北方半球也强烈影响这一梯度，造成萨赫勒干旱。利用1900年至2010年的去趋势观测，我们发现萨赫勒地区四个最干燥的夏天中有三个是在北方半球火山爆发之前。我们使用一个最先进的全球大气-海洋耦合模型来模拟间歇性火山爆发和通过持续故意注入平流层的地球工程。在这两种情况下，大量不对称的平流层气溶胶负荷集中在北方半球是萨赫勒干旱的预兆，而那些集中在南半球导致萨赫勒绿化。需要进一步研究对萨赫勒和其他脆弱地区的详细区域影响，以便在实施任何实际的太阳辐射管理地球工程计划之前，为决策者提供信息，制定谨慎的协商一致的全球治理。
The Sahelian drought of the 1970s-1990s was one of the largest humanitarian disasters of the past 50 years, causing up to 250,000 deaths and creating 10 million refugees(1). It has been attributed to natural variability(2-5), over-grazing(6) and the impact of industrial emissions of sulphur dioxide(7,8). Each mechanism can influence the Atlantic sea surface temperature gradient, which is strongly coupled to Sahelian precipitation(2,3). We suggest that sporadic volcanic eruptions in the Northern Hemisphere also strongly influence this gradient and cause Sahelian drought. Using de-trended observations from 1900 to 2010, we show that three of the four driest Sahelian summers were preceded by substantial Northern Hemisphere volcanic eruptions. We use a state-of-the-art coupled global atmosphere-ocean model to simulate both episodic volcanic eruptions and geoengineering by continuous deliberate injection into the stratosphere. In either case, large asymmetric stratospheric aerosol loadings concentrated in the Northern Hemisphere are a harbinger of Sahelian drought whereas those concentrated in the Southern Hemisphere induce a greening of the Sahel. Further studies of the detailed regional impacts on the Sahel and other vulnerable areas are required to inform policymakers in developing careful consensual global governance before any practical solar radiation management geoengineering scheme is implemented.