For the first time, a University of Maryland-led team (Warmer et al.) revealed, in Geophysical Research Letters, a global atmospheric NH3 — Ammonia from 2002 to 2016 over four of the world’s more productive agricultural regions: United States, Europes, China and India. All these countries show increased NH3 concentrations!
NH3 concentrations are estimated from the NASA’s Atmospheric Infrared Sounder (AIRS) instrument on NASA’s Aqua satellite. Like NO2 – Nitrogen dioxide, NH3 is part of the nitrogen cycle and a precursor of ammonium and nitrate aerosols. Excess reactive nitrogen reduces biodiversity and causes harmful algal blooms and anoxic conditions. Dry deposition of gaseous ammonia may have substantially greater adverse impacts on ecosystem health than deposition of ammonium in aerosols or precipitation. The main sources of atmospheric NH3 are farming and animal husbandry involving reactive nitrogen ultimately derived from fertilizer use. The rate of these emissions is also sensitive to climate change.
In the abstract, Warmer et al., (2017) says: “Significant increasing trends are seen over the U.S. (2.61% yr-1 ), the European Union (EU) (1.83% yr-1 ), and China (2.27% yr-1 ). Over the EU, the trend results from decreased scavenging by acid aerosols. Over the U.S., the increase results from a combination of decreased chemical loss and increased soil temperatures. Over China, decreased chemical loss, increasing temperatures, and increased fertilizer use all play a role. Over South Asia, increased NH3 emissions are masked by increased SO2 – Sulphur dioxide and NOx – Nitrogen oxides emissions, leading to increased aerosol loading and adverse health effects”.