【環境】サハラ砂漠の風が北アフリカの塵放出量に影響する

Variability in North African dust production is strongly influenced by the pattern of surface winds in the Sahara desert, reports a paper published in this week’s Nature. The study also finds that dust production can be excited by any weather phenomenon that affects wind speeds over the continent, such as the North Atlantic Oscillation, the El Nino/Southern Oscillation and the West African Monsoon.

Amato Evan and colleagues show that the surface wind pattern in the Sahara reflects its topography, and use this mode of wind variability to estimate dust production as far back as 1851. They identify two persistent periods of elevated dustiness (the 1910s to the 1940s and the 1970s to the 1980s) and three periods of low dust production (the 1860s, the 1950s and the 2000s).

Finally, using climate models, they find a slight but statistically significant decline in dust production associated with increasing emissions of greenhouse gases during the twenty-first century. Such a reduction in dust production may have a positive impact on human health, due to an associated improvement in air quality and increased rainfall, the authors suggest. However, the fall in dust levels may enhance the warming of the tropical North Atlantic beyond that expected from increases in greenhouse gases alone, giving rise to more hurricanes, they conclude.