Air pollution expanding tropics
The hole in the ozone layer has already been shown to expand tropics in the Southern Hemisphere, but this is the first study to show that black carbon and ozone pollution is doing the same in the Northern Hemisphere. Image: ermingut/iStockphoto Black carbon aerosols and ozone, both man-made pollutants emitted predominantly in the Northern Hemisphere’s low- to mid-latitudes, are most likely pushing the boundary of the tropics further poleward in that hemisphere, new research by a team of scientists shows.While depletion of the ozone layer high up in the stratosphere has already been shown to be the primary driver of the expansion of the tropics in the Southern Hemisphere, the researchers are the first to report that black carbon and ozone pollution nearer the Earth’s surface are probably doing likewise in the Northern Hemisphere.The study results appear in the May 17 issue of the journal Nature. Climatologist Robert J. Allen, at the...