Tropics widening, drought threat grows

A new study in the scientific journal Nature suggests that two human-caused pollutants, black carbon aerosols and tropospheric ozone, are causing the boundary of Earth's tropics to expand, a change which may worsen drought in the subtropics. According to Climate Progress: "Led by climatologist Robert J. Allen, an assistant professor of Earth sciences at the University of California, Riverside, the research team notes that an unabated tropical belt expansion would impact large-scale atmospheric circulation, especially in the subtropics and mid-latitudes. "'If the tropics are moving poleward, then the subtropics will become even drier,' Allen said. 'If a poleward displacement of the mid-latitude storm tracks also occurs, this will shift mid-latitude precipitation poleward, impacting regional agriculture, economy, and society.'"