Glob. Biogeochem. Cycles http://doi.org/nsf (2013)

Credit: © PER KARLSSON BKWINE.COM/ALAMY

Soils are a significant source of atmospheric nitrous oxide, a potent greenhouse gas that also contributes to the depletion of stratospheric ozone. Numerical simulations suggest that the El Niño/Southern Oscillation modifies soil nitrous oxide emissions on a global scale.

Eri Saikawa, of Emory University, Atlanta, and colleagues examined seasonal and interannual variability in soil nitrous oxide emissions around the globe between 1975 and 2008, using a model that broadly captures emissions at a coarse scale. According to their simulations, emissions were lower than average during El Niño years, and higher than average during La Niña years. This pattern was apparent in North America, South America, southern Asia and central and equatorial Africa, regions particularly affected by the El Niño/Southern Oscillation.

Emissions of nitrous oxide from soils were strongly correlated with soil water content in equatorial regions and with temperature in the Northern Hemisphere, suggesting that perturbations to both parameters contributed to the simulated emission anomalies.