Hot colors represent increases from a combination of increased fertilizer application, reduced scavenging by acid aerosols and climate warming. Cool colors show decreases due to reduced agricultural burning or fewer wildfires. ; The first global, long-term satellite study of airborne ammonia gas has revealed “hotspots” of the pollutant over four of the world’s most productive agricultural regions. The results of the study, conducted using data from NASA’s Atmospheric Infrared Sounder (AIRS) instrument on NASA’s Aqua satellite, could inform the development of strategies to control pollution from ammonia and ammonia byproducts in Earth’s agricultural areas.

A University of Maryland-led team discovered steadily increasing ammonia concentrations from 2002 to 2016 over agricultural centers in the United States, Europe, China and India. Increased concentrations of atmospheric ammonia are linked to poor air and water quality.

The NASA-funded study, published March 16 in Geophysical Research Letters, describes probable causes for the observed increased airborne ammonia concentrations in each region. Although specifics vary between areas, the increases are broadly tied to crop fertilizers, livestock animal wastes, changes to atmospheric chemistry, and warming soils that retain less ammonia.