Using a methane-specific land cover model to improve bottom-up estimates of pan-Arctic biogenic methane emissions
Abstract
Bottom-up estimates of CH4 emissions from the arctic and sub-arctic are 2-3 times higher than top-down inversion model estimates and include high uncertainties. Lakes alone are estimated to emit ~16 Tg C a year, ~70% of the total natural CH4 estimate for the north. Uncertainties and the likely overestimate of bottom-up emissions largely stem from relying on upscaling land cover classes that are too coarse in resolution. For example, using one methane emission value for all wetlands or lakes likely over-estimates total emissions. General bias to conduct field studies on lakes that are high emitters of CH4 may also skew the "average" flux values attributed to lakes for upscaling. Furthermore, we have poor constraints on the spatial extents of wetlands and small lakes in the north. Different definitions of wetlands across Arctic countries and low-resolution maps lead to "double counting" of CH4 emissions from wetlands and lakes. In this study we use a CH4 specific land cover model, which addresses double counting, and detailed land cover classes to produce a more constrained estimate of bottom-up CH4 emissions from the pan-Arctic region. To model the empirical relationships between land cover classes and CH4, we use the most recent CH4 emission database, including new empirical flux measurements from lakes in the previously unstudied Taiga Plains region of Canada. We expect the results of our study to provide a more constraint estimate of bottom up estimates across the circumpolar region.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B23D..01K
- Keywords:
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- 0426 Biosphere/atmosphere interactions;
- BIOGEOSCIENCES;
- 0475 Permafrost;
- cryosphere;
- and high-latitude processes;
- BIOGEOSCIENCES;
- 0497 Wetlands;
- BIOGEOSCIENCES;
- 1615 Biogeochemical cycles;
- processes;
- and modeling;
- GLOBAL CHANGE