Global atmospheric ammonia trends measured from space from 2002 to 2016. 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.

(Juying Warner/GRL)

Ammonia hot spotsareincreasing in the Earth's atmosphere above regions withhigh agricultural productivity, according to a new study.

Using data from NASA satellites to track concentrations of ammonia in Earth's atmosphere from 2002 to 2016, scientists with the University of Maryland found higher concentrations over farmlands of the United States, Europe, China and India.

The colorless , including respiratory distress.

According to the , most excess ammonia comes from fertilizer use and animal waste. The researchers say rising concentrations of ammonia may also be linked to climate change and warmer soils, which absorb less ammonia.

"Measuring ammonia from the ground is difficult, but the satellite-based method we have developed allows us to track ammonia efficiently and accurately," Juying Warner, atmospheric and oceanic science researcher at Maryland,. "We hope that our results will help guide better management of ammonia emissions."

While fertilizer use has not increased in the United States in recent years, scientistsbelieveefforts to eliminate acid rain through stricter emissions standardshas had a role inthe ever-increasing levels of ammonia in the atmosphere. Ironically, acid rain actually helps eliminate ammonia from the air.

"The decrease in acid rain is a good thing. Aerosol loading has plummeted — a substantial benefit to us all," said Russell Dickerson, a professor of atmospheric and oceanic science at Maryland. "But it has also increased gaseous ammonia loading, which we can see from space."

Fertilizer use may be on the decrease in the U.S., but in countries like China and India, fertilizer is on the rise as meat becomes more popular.

"The increase in ammonia has spiked aerosol loading in China. This is a major contributor to the thick haze seen in Beijing during the winter, for example," Warner said. "Also, meat is becoming a more popular component of the Chinese diet. As people shift from a vegetarian to a meat-based diet, ammonia emissions will continue to go up."