Stable isotopes provide revised global limits of aerobic methane emissions from plants D. F. Ferretti1,2, J. B. Miller3, J. W. C. White1, K. R. Lassey2, D. C. Lowe2, and D. M. Etheridge4 1University of Colorado, Boulder, CO, USA 2National Institute of Water and Atmospheric Research Ltd, Wellington, New Zealand 3National Oceanographic and Atmospheric Administration, Boulder, CO, USA 4Marine and Atmospheric Research, Commonwealth Scientific and Industrial Research Organisation, Aspendale, Victoria, Australia
Abstract. Recently Keppler et al. (2006) discovered a surprising new source of methane
– terrestrial plants under aerobic conditions, with an estimated global
production of 62–236 Tg yr−1 by an unknown mechanism. This is ~10–40% of the annual total of methane entering the modern atmosphere
and ~30–100% of annual methane entering the pre-industrial (0 to
1700 AD) atmosphere. Here we test this reported global production of methane
from plants against ice core records of atmospheric methane concentration
(CH4) and stable carbon isotope ratios (δ13CH4) over
the last 2000 years. Our top-down approach determines that global plant
emissions must be much lower than proposed by Keppler et al. (2006) during
the last 2000 years and are likely to lie in the range 0–46 Tg yr−1 and
0–176 Tg yr−1 during the pre-industrial and modern eras, respectively.
Citation: Ferretti, D. F., Miller, J. B., White, J. W. C., Lassey, K. R., Lowe, D. C., and Etheridge, D. M.: Stable isotopes provide revised global limits of aerobic methane emissions from plants, Atmos. Chem. Phys., 7, 237-241, doi:10.5194/acp-7-237-2007, 2007.