Landscape Ecology

, Volume 29, Issue 4, pp 571–577 | Cite as

On the challenges of modeling the net radiative forcing of wetlands: reconsidering Mitsch et al. 2013

Perspective

Abstract

Wetlands play a role in regulating global climate by removing carbon dioxide (CO2) from the atmosphere and sequestering it as soil carbon, and by emitting methane (CH4) and nitrous oxide (N2O) to the atmosphere. In a recent article in this journal (Mitsch et al. Landscape Ecol 28:583–597, 2013), CO2 sequestration and CH4 emissions were modeled for several freshwater wetlands that vary in vegetation type, climate, and hydrology. The authors of that study made significant errors that caused them to underestimate the importance of wetland CH4 emissions on climate dynamics. Here, I reanalyze the Mitsch et al. dataset and show that all of their wetlands had an initial warming effect but eventually caused negative net radiative forcing within ~60–14,000 years, depending on the ratio of CO2 sequestration to CH4 emissions. The addition of a N2O component to the model suggested that typical wetland N2O emission rates would contribute only a minor burden to wetland radiative forcing, although specific application of this three-gas model is limited by the paucity of sites where CO2 sequestration, CH4 emission, and N2O exchange rates have all been measured. Across the landscape, many natural wetlands may already cause negative net radiative forcing when integrated over their lifetime. However, caution should be applied when using carbon sequestration as a rationale for designing wetland construction and restoration projects since freshwater wetlands may have a net positive (warming) effect on climate for decades to centuries or longer.

Keywords

Carbon sequestration Climate change Global warming potential Swamp Tidal freshwater marsh Wetland restoration 

Notes

Acknowledgments

I thank Pat Megonigal, Scott Bridgham, and an anonymous reviewer for comments that significantly improved this manuscript. I also thank Steve Frolking for kindly answering questions about his atmospheric perturbation model.

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Copyright information

© Springer Science+Business Media Dordrecht 2014

Authors and Affiliations

  1. 1.Department of BiologyVirginia Commonwealth UniversityRichmondUSA

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