Air pollution in the Northern Hemisphere in the mid-20th century cooled the upper half of the planet and pushed rain bands south, contributing to the prolonged and worsening drought in Africa's Sahel region. Clean air legislation in the 1980s reversed the trend and the drought lessened.
Fuente : http://www.eurekalert.org/pub_releases/2013-06/uow...
Fuente : http://www.eurekalert.org/pub_releases/2013-06/uow...