Increased Atmospheric CO2 Increases Emissions of Potent Greenhouse Gases from Soils
Increasing concentrations of atmospheric carbon dioxide (CO2) can affect biotic and abiotic conditions, such as microbial activity and water content, in soil. In turn, these changes might be expected to alter the production and consumption of the important greenhouse gases nitrous oxide (N2O) and methane (CH4). However, studies on fluxes of N2O and CH4 from soil under increased atmospheric CO2 have not been quantitatively synthesized. Here, a DOE-funded study from Northern Arizona University used a meta-analysis of increasing CO2 (ranging from 463 to 780 ppm by volume), demonstrating that increasing CO2 stimulates both N2O emissions from upland soils and CH4 emissions from rice paddies and natural wetlands. Because enhanced greenhouse-gas emissions add to the radiative forcing of terrestrial ecosystems, these emissions are expected to negate at least 16.6% of the climate change mitigation potential previously predicted from an increase in the terrestrial carbon sink under increased atmospheric CO2 concentrations. The study’s results, therefore, suggest that the capacity of land ecosystems to slow climate warming has been overestimated.
van Groenigen, K. J., C. W. Osenberg, and B. A. Hungate. 2011. “Increased Soil Emissions of Potent Greenhouse Gases under Increased Atmospheric CO2,” Nature 475, 214-216. DOI:10.1038/nature10176.