Global warming impacts of nitrogen use in agriculture: an assessment for India since 1960

摘要

Global warming impacts of N use in Indian agriculture since 1960 was estimated for 20- and 100-year time scales using equation-based empirical method. During 2014, total Warming in terms of global temperature change potential (GTP) for a 20-year time scale (GTP(20)) was assessed as 217.31 +/- 17.74 Tg CO(2)e, and for a 100-year time scale (GTP(100)) was 217.78 +/- 17.78 Tg CO(2)e. N2O contributed 90% and 99%of the GTP(20) and GTP(100), respectively. Total cooling impacts were 94.86 +/- 7.75 and 50.36 +/- 4.11 Tg CO(2)e on GTP(20) and GTP(100), respectively. Aerosols of NH3 and NOx, NOx-induced O-3 and CH4 alteration, and N-induced C sequestration contributed 41, 6 and 51%, respectively, to GTP(20), however, N-induced C sequestration contributed about 99% to GTP(100). Net warming impacts were 122.45 +/- 10.00 and 167.42 +/- 13.67 Tg CO(2)e on GTP(20) and GTP(100), respectively. Net warming impacts were lowered by 10% and 1% compared to total warming, and 37% and 23% compared to warming caused by N2O alone, for GTP(20) and GTP(100), respectively. Usually, to estimate the global warming impacts of N use in agriculture, the warming effects of only N2O emission are considered. However, both warming and cooling impacts should be considered to capture the net impacts of N use in agriculture on climate change.