Global temperature change potential of nitrogen use in agriculture: A 50-year assessment

Nitrogen (N) use in agriculture substantially alters global N cycle with the short- and long-term effects on global warming and climate change. It increases emission of nitrous oxide, which contributes 6.2%, while carbon dioxide and methane contribute 76% and 16%, respectively of the global warming. However, N causes cooling due to emission of NO x , which alters concentrations of tropospheric ozone and methane. NO x and NH 3 also form aerosols with considerable cooling effects. We studied global temperature change potential (GTP) of N use in agriculture. The GTP due to N 2 O was 396.67 and 1168.32 Tg CO 2 e on a 20-year (GTP 20 ) and 439.94 and 1295.78 Tg CO 2 e on 100-year scale (GTP 100 ) during years 1961 and 2010, respectively. Cooling effects due to N use were 92.14 and 271.39 Tg CO 2 e (GTP 20 ) and 15.21 and 44.80 Tg CO 2 e (GTP 100 ) during 1961 and 2010, respectively. Net GTP 20 was 369.44 and 1088.15 Tg CO 2 e and net GTP 100 was 429.17 and 1264.06 Tg CO 2 e during 1961 and 2010, respectively. Thus net GTP 20 is lower by 6.9% and GTP 100 by 2.4% compared to the GTP considering N 2 O emission alone. The study shows that both warming and cooling effects should be considered to estimate the GTP of N use.