Predominance of methanogens over methanotrophs in rewetted fens characterized by high methane emissions Biogeosciences DOI 10.5194/bg-15-6519-2018 6 November 2018 Rewetting drained peatlands may lead to prolonged emission of the greenhouse gas methane, but the underlying factors are not well described. In this study, we found two rewetted fens with known high methane fluxes had a high ratio of microbial methane producers to methane consumers and a low abundance of methane consumers compared to pristine wetlands. We therefore suggest abundances of methane-cycling microbes as potential indicators for prolonged high methane emissions in rewetted peatlands. Read more
Regional variation in the effectiveness of methane-based and land-based climate mitigation options Earth System Dynamics DOI 10.5194/esd-12-513-2021 23 June 2021 We model greenhouse gas emission scenarios consistent with limiting global warming to either 1.5 or 2 °C above pre-industrial levels. We quantify the effectiveness of methane emission control and land-based mitigation options regionally. Our results highlight the importance of reducing methane emissions for realistic emission pathways that meet the global warming targets. For land-based mitigation, growing bioenergy crops on existing agricultural land is preferable to replacing forests. Read more
Quantifying methane emissions from the global scale down to point sources using satellite observations of atmospheric methane Atmospheric Chemistry and Physics DOI 10.5194/acp-22-9617-2022 2 November 2022 We review the capability of satellite observations of atmospheric methane to quantify methane emissions on all scales. We cover retrieval methods, precision requirements, inverse methods for inferring emissions, source detection thresholds, and observations of system completeness. We show that current instruments already enable quantification of regional and national emissions including contributions from large point sources. Coverage and resolution will increase significantly in coming years. Read more
Terrestrial methane emissions from the Last Glacial Maximum to the preindustrial period Climate of the Past DOI 10.5194/cp-16-575-2020 7 April 2020 We investigate the changes in natural methane emissions between the Last Glacial Maximum and preindustrial periods with a methane-enabled version of MPI-ESM. We consider all natural sources of methane except for emissions from wild animals and geological sources. Changes are dominated by changes in tropical wetland emissions, high-latitude wetlands play a secondary role, and all other natural sources are of minor importance. We explain the changes in ice core methane by methane emissions only. Read more
Autonomous methane seep site monitoring offshore western Svalbard: hourly to seasonal variability and associated oceanographic parameters Ocean Science DOI 10.5194/os-18-233-2022 6 May 2022 Natural sources of atmospheric methane need to be better described and quantified. We present time series from ocean observatories monitoring two seabed methane seep sites in the Arctic. Methane concentration varied considerably on short timescales and seasonal scales. Seeps persisted throughout the year, with increased potential for atmospheric release in winter due to water mixing. The results highlight and constrain uncertainties in current methane estimates from seabed methane seepage. Read more
Highest methane concentrations in an Arctic river linked to local terrestrial inputs Biogeosciences DOI 10.5194/bg-19-5059-2022 16 January 2023 Permafrost thaw releases methane that can be emitted into the atmosphere or transported by Arctic rivers. Methane measurements are lacking in large Arctic river regions. In the Kolyma River (northeast Siberia), we measured dissolved methane to map its distribution with great spatial detail. The river’s edge and river junctions had the highest methane concentrations compared to other river areas. Microbial communities in the river showed that the river’s methane likely is from the adjacent land. Read more
Quantifying the loss of processed natural gas within California’s South Coast Air Basin using long-term measurements of ethane and methane Atmospheric Chemistry and Physics DOI 10.5194/acp-16-14091-2016 15 November 2016 This paper investigates the cause of the known underestimate of bottom-up inventories of methane in California’s South Coast Air Basin (SoCAB). We use total column measurements of methane, ethane, carbon monoxide, and other trace gases beginning in the late 1980s to calculate emissions and attribute sources of excess methane to the atmosphere. We conclude that more than half of the excess methane to the SoCAB atmosphere is attributable to processed natural gas. Read more
Detectability of Arctic methane sources at six sites performing continuous atmospheric measurements Atmospheric Chemistry and Physics DOI 10.5194/acp-17-8371-2017 11 July 2017 Atmospheric methane simulations in the Arctic have been made for 2012 and compared to continuous observations at six measurement sites. All methane sources significantly affect the measurements at all stations, at least at the synoptic scale, except for biomass burning. An appropriate modelling framework combined with continuous observations of atmospheric methane enables us to gain knowledge on regional methane sources, including those which are usually poorly represented, such as freshwater. Read more
Global distribution of methane emissions, emission trends, and OH concentrations and trends inferred from an inversion of GOSAT satellite data for 2010–2015 Atmospheric Chemistry and Physics DOI 10.5194/acp-19-7859-2019 12 June 2019 We use 2010–2015 satellite observations of atmospheric methane to improve estimates of methane emissions and their trends, as well as the concentration and trend of tropospheric OH (hydroxyl radical, methane’s main sink). We find overestimates of Chinese coal and Middle East oil/gas emissions in the prior estimate. The 2010–2015 growth in methane is attributed to an increase in emissions from India, China, and areas with large tropical wetlands. The contribution from OH is small in comparison. Read more
High-frequency monitoring of anomalous methane point sources with multispectral Sentinel-2 satellite observations Atmospheric Measurement Techniques DOI 10.5194/amt-14-2771-2021 31 May 2021 Satellites can detect methane emissions by measuring sunlight reflected from the Earth’s surface and atmosphere. Here we show that the European Space Agency’s Sentinel-2 twin satellites can be used to monitor anomalously large methane point sources around the world, with global coverage every 2–5 days and 20 m spatial resolution. We demonstrate this previously unreported capability through high-frequency Sentinel-2 monitoring of two strong methane point sources in Algeria and Turkmenistan. Read more