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Nitrous Oxide (N2O) Fluxes from Temperate Grasslands in a Warmer, Wetter and CO2-Enriched World
Cantarel, A.A.M., Bloor, J.M.G., Deltroy, N. and Soussana, J.-F. 2011. Effects of climate change drivers on nitrous oxide fluxes in an upland temperate grassland. Ecosystems 14: 223-233.

The authors write that nitrous oxide (N2O) is "an influential greenhouse gas, with a global warming potential approximately 300 times that of CO2 (IPCC, 2001)," and they say it "has shown linear increases of 0.2-0.3% per year over the last few decades, largely as a result of changes in agricultural practices and direct emissions from agricultural soils (IPCC, 2007)." However, they note that "no studies to date have investigated the impacts of projected climate change scenarios on N2O emissions"

What was done
In an effort designed to begin filling this research void, Cantarel et al. monitored N2O fluxes in an in situ ecosystem manipulation experiment simulating the climate predicted for the study area (an upland temperate grassland in the French Massif Central region), making use of the Clermont Climate Change Experiment facility, where Bloor et al. (2010) were conducting "a long-term grassland study of multiple climate changes applied in an additive experimental design." Thus, over a two-year period, they monitored N2O fluxes under conditions "simulating the climate predicted for the study area in 2080 (3.5°C temperature increase, 20% reduction in summer rainfall and atmospheric CO2 levels of 600 ppm)."

What was learned
"Overall," as the four researchers describe the results of their study, "experimental warming had a positive effect on the annual N2O emissions." However, and "contrary to expectations," as they put it, "combined summer drought and warming had no significant effect on mean N2O fluxes recorded at any time," nor did "elevated CO2 in combination with warming and drought."

What it means
Because "neither combined summer drought and warming nor the simultaneous application of elevated atmospheric CO2 concentrations, summer drought and warming had any significant effect on annual N2O fluxes," it would appear that if climate change proceeded as predicted for this particular part of the world, it would likely not be magnified to any significant degree by climate-change-induced increases in ecosystem N2O emissions.

Bloor, J.M.G., Pichon, P., Falcimagne, R., Leadley, P. and Soussana, J.F. 2010. Effects of warming, summer drought and CO2 enrichment on aboveground biomass production, flowering phenology and community structure in an upland grassland ecosystem. Ecosystems 13: 888-900.

IPCC. 2001. McCarthy, J.J., Canzani, O.F., Leary, N.A., Dokken, D.J. and White, K.S. (Eds.) Climate Change 2001: Contribution of the Working Group II to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom.

IPCC. 2007. Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K.B., Tignor, M. and Miller, H.L. (Eds.) Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom.

Reviewed 20 April 2011