Publication Abstracts

Matthews 2000

Matthews, E., 2000: 12. Wetlands. In Atmospheric Methane: Its Role in the Global Environment. M.A.K. Khalil, Ed., Springer Verlag, pp. 202-233.

Wetlands are most likely the largest natural source of methane to the atmosphere accounting for ∼20% of the current global annual emission of ∼450-550 Tg (1012 g). Wetlands were the dominant preindustrial source with smaller contributions from wild fires, animals and oceans. Currently, the total annual emission of methane is about twice that estimated for the pre-industrial period, but both the relative and absolute contribution of wetlands is smaller than in the past due to increases in anthropogenic sources and reductions in wetland areas. However, climate and related biological interactions that presently control the distribution of wetlands and their methane emissions are expected to change during the next 50 to 100 years.

The role of wetlands in the cycle of methane has been studied for several decades. Early estimates of emissions were based on very few measurements and highly uncertain information about the wetland areal extent. Using newer information about wetland distributions and environmental characteristics, estimates have converged around 100 Tg CH4/yr. Using global wetland areas of 5-6×1012 m2. Recent modeling studies are consistent with these values. However, the similarities mask some major uncertainties about seasonal methane-production periods as well as important differences in the relative importance of the role of climatically and ecologically distinct wetland ecosystems, i.e., tropical/subtropical wetlands whose methane emissions are governed generally by large scale precipitation and flood cycles, and high-latitude wetlands whose highly seasonal emissions are controlled via interactions between temperature and water cycles. A complex suite of environmental parameters including soil chemistry, substrate quality and soil water status influence emissions in all these environments, further complicating the task of evaluating emissions.

Several developments in understanding the role of wetlands in the global methane cycle took place beginning in the late 1980s. Data on measured methane fluxes in wetland ecosystems expanded substantially. Measurements of concentrations and isotopic composition of atmospheric methane continued, providing more comprehensive information about sources, trends and seasonal cycles of methane. Modeling and synthesis techniques for analyzing the terrestrial and atmospheric information improved. Most recently, models of large-scale methane emissions, as well as the distribution of wetlands themselves, have made their appearance.

This chapter provides an overview of the role of natural wetlands in the global cycle of methane.

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BibTeX Citation

@inbook{ma04100j,
  author={Matthews, E.},
  editor={Khalil, M. A. K.},
  title={12. Wetlands},
  booktitle={Atmospheric Methane: Its Role in the Global Environment},
  year={2000},
  pages={202--233},
  publisher={Springer Verlag},
  address={Berlin/Heidelberg},
}

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RIS Citation

TY  - CHAP
ID  - ma04100j
AU  - Matthews, E.
ED  - Khalil, M. A. K.
PY  - 2000
TI  - 12. Wetlands
BT  - Atmospheric Methane: Its Role in the Global Environment
SP  - 202
EP  - 233
PB  - Springer Verlag
CY  - Berlin/Heidelberg
ER  -

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