Title

Climate / Greenhouse Gas Feedbacks in Northern Peatlands

Abstract

Wetlands are relatively unique ecosystems in relation to greenhouse gas exchange. They often are net sinks for CO$_{2}$, and at the same time can be small to large sources of CH$_{4}$. In considering the effect of climate change on wetlands, the magnitude and direction of change in flux of both CO$_{2}$ and CH$_{4}$ must be considered. However, assessment of the strength of the climate feedback is not straight forward since CO$_{2}$ and CH$_{4}$ have different atmospheric life times and radiative strengths. We examine this problem by coupling a simple model of CO$_{2}$ and CH$_{4}$ perturbations to the atmosphere with a simple model that calculates carbon accumulation and methane emission for northern peatlands and is driven by mean climate data. We examine two cases of climate perturbation impacts and feedbacks for an eastern North American peatland: (1) a bog that has reached quasi-equilibrium ($\sim$15 kyr, representing a possible climax state), with net CO$_{2}$ flux about zero and a very small CH$_{4}$ flux; and (2) a bog that has not reached equilibrium ($\sim$8.5 kyr, representing a possible contemporary state), with net CO$_{2}$ uptake of about 20 g C m$^{-2}$ yr$^{-1}$ and CH$_{4}$ emission around 0 to 5 g m$^{-2}$ yr$^{-1}$. For the climate perturbation, we changed mean annual precipitation by $\pm$5%, $\pm$10%, and $\pm$20%. The results show that while the exchanges of CO$_{2}$ and CH$_{4}$ are affected by climate perturbation, they return to the conditions prior to the perturbation in several hundred years. These changed fluxes affect atmospheric burdens, and feedbacks to climate occur through changes in radiative forcing by CO$_{2}$ and CH$_{4}$.

Publication Date

12-2004

Journal Title

EOS, Transactions American Geophysical Union, Fall Meeting, Supplement

Publisher

American Geophysical Union Publications

Document Type

Conference Proceeding