Predicting enhanced wetland greenhouse gas emissions in response to climate change

Gordon R.McNicol

University of Waterloo

"Predicting enhanced wetland greenhouse gas emissions in response to climate change"

Wetlands are characterised by the interaction of soil with seasonal or permanent water bodies and serve several crucial ecological functions including flood prevention and water filtration. Moreover, serving as a boundary between land and aquatic environments, they provide diverse ecosystems for a variety of plants, animals and microbes. However, the ability of wetlands to sequester and store carbon also secures their place as the largest natural source of methane emissions. These emissions are strongly dependent on both the relative depth of the water table to the soil and the soil temperature, with submerged warm soil providing favourable anaerobic conditions for methanogenesis by microbes and detrimental to methane consumption through oxidation. Hence, wetland methane emissions are strongly susceptible to climate change, particularly changes in rainfall and temperature. We present a mathematical model to describe the stochastic movement of the water table coupled to a simple set of ODEs describing methane production, oxidation, and emission, parameterised by this water table depth. We employ this model to predict how the inherent variations in water table depth due to the soil profile leads to changing emission profiles across individual wetlands. Moreover, by exploring the sensitivity of these emissions to rainfall and temperature changes, we demonstrate during wetland conservation efforts the need to consider how climate change will influence emissions.
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