Methane loss during the early 21st century: Observational constraints on hydroxyl abundance
Abstract
Atmospheric methane has increased concurrent with anthropogenic emissions since the early twentieth century. The recent hiatus in atmospheric growth from 2000-2006 prompted several studies of methane isotopes and methylchloroform that suggest a substantial shift in the concentration of the tropospheric hydroxyl radical. However, the bottom-up uncertainties in methane emissions as well as the posterior uncertainties in the constraint on the hydroxyl sink are large. We focus on the drivers of the hydroxyl sink of methane, using observationally-constrained changes in several of the factors controlling the abundance of hydroxyl to construct a plausible budget for its concentration from 2005 to 2015, including NOx and CO emissions, humidity, and overhead ozone column burden. We find that the large shift in methane lifetime suggested by top-down studies of methyl chloroform is unlikely to be explained by a change in hydroxyl concentrations.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.B33E2133W
- Keywords:
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- 3322 Land/atmosphere interactions;
- ATMOSPHERIC PROCESSES;
- 0475 Permafrost;
- cryosphere;
- and high-latitude processes;
- BIOGEOSCIENCES;
- 0497 Wetlands;
- BIOGEOSCIENCES;
- 1836 Hydrological cycles and budgets;
- HYDROLOGY