Methane emissions from high-latitude wetlands: a full annual cycle of emissions using a new wetland data set, gorwing- and off-season flux observations and satellite-derived freeze-thaw dynamics
Abstract
Methane emissions from high-latitude wetlands and lakes account for about one-third of global wetland and lake emissions annually which, in turn, account for about one-third of total annual methane emissions from all sources. The dominant approach to modeling wetland emissions is to identify 'wetlands' (aka methane-emitting areas) from satellite-derived observations of surface inundation which include, but do not distinguish among, flooded wetlands, lakes, rivers, reservoirs, and irrigated rice fields while missing non-flooded wetlands; for the most part, this strategy treats all 'wetlands' the same. Problems with the approach include applying terrestrial wetland models to inundated areas; ignoring differences in both emission processes and sensitivities occurring in lakes and in wetlands; ignoring the comprehensive observational literature that confirms environmental and emission differences among individual ecosystems within each of these sources; and mixing lake areas with those of wetlands and modeling them all as wetlands. The result is that the magnitude, seasonality and trend in wetland vs lake emissions are not known. We report on a new wetland data set identifying 10 high-latitude wetland types explicitly linked to the same ecosystem types represented in the recent flux compilation of Treat et al. (2018) comprising both growing- and off-season fluxes. We present the annual cycle of methane emissions from this suite of high-latitude wetland types driven by satellite-derived freeze-thaw dynamics. We juxtapose the new, high-latitude wetland data set and associated methane emissions with our mutually-exclusive estimate of high-latitude lake classes and emissions to illustrate the importance of employing mutually-exclusive data sets to understand and predict current and future methane emissions from wetlands and from lakes.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B41G2784M
- Keywords:
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- 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 0475 Permafrost;
- cryosphere;
- and high-latitude processes;
- BIOGEOSCIENCESDE: 0497 Wetlands;
- BIOGEOSCIENCES