By Sid Perkins
Thick clouds of air pollution over southern Asia and increased concentrations of greenhouse gases in the atmosphere worldwide have restricted rice harvests in India for the past 2 decades, a new analysis suggests.
Aerosols, such as volcanic ash and industrial soot, typically cool Earth’s surface by reflecting some solar radiation back into space. This phenomenon somewhat counteracts the planet-warming effect of increased concentrations of gases such as carbon dioxide, says V. Ram Ramanathan, a climate scientist at the Scripps Institution of Oceanography in La Jolla, Calif.