Focusing on a little-studied organic carbon compound could help unlock how air pollution affects South Asia’s unique climate patterns and agriculture, scientists say.

An international research team studied a heat-trapping aerosol known as brown carbon and discovered that in regions that are already polluted—such as the Indian subcontinent—its impacts are proportionally much greater than in areas where the air is cleaner, such as in the U.S.

Brown carbon—which most climate models don’t capture in their analysis—could play a part...