Showing papers on "Atmospheric methane published in 2022"
TL;DR: In this paper , the authors collected and analyzed hundreds of very large releases from atmospheric methane images sampled by the TROPOspheric Monitoring Instrument (TROPOMI) between 2019 and 2020.
Abstract: Methane emissions from oil and gas (O&G) production and transmission represent a considerable contribution to climate change. These emissions comprise sporadic releases of large amounts of methane during maintenance operations or equipment failures not accounted for in current inventory estimates. We collected and analyzed hundreds of very large releases from atmospheric methane images sampled by the TROPOspheric Monitoring Instrument (TROPOMI) between 2019 and 2020. Ultra-emitters are primarily detected over the largest O&G basins throughout the world. With a total contribution equivalent to 8 to 12% (~8 million metric tons of methane per year) of the global O&G production methane emissions, mitigation of ultra-emitters is largely achievable at low costs and would lead to robust net benefits in billions of US dollars for the six major O&G-producing countries when considering societal costs of methane.
61 citations
TL;DR: In this paper , the capability of current and scheduled satellite observations of atmospheric methane in the shortwave infrared (SWIR) to quantify methane emissions from the global scale down to point sources is reviewed.
Abstract: Abstract. We review the capability of current and scheduled satellite
observations of atmospheric methane in the shortwave infrared (SWIR) to
quantify methane emissions from the global scale down to point sources. We
cover retrieval methods, precision and accuracy requirements, inverse and
mass balance methods for inferring emissions, source detection thresholds,
and observing system completeness. We classify satellite instruments as area
flux mappers and point source imagers, with complementary attributes. Area
flux mappers are high-precision (<1 %) instruments with 0.1–10 km
pixel size designed to quantify total methane emissions on regional to
global scales. Point source imagers are fine-pixel (<60 m)
instruments designed to quantify individual point sources by imaging of the
plumes. Current area flux mappers include GOSAT (2009–present), which
provides a high-quality record for interpretation of long-term methane
trends, and TROPOMI (2018–present), which provides global continuous daily
mapping to quantify emissions on regional scales. These instruments already
provide a powerful resource to quantify national methane emissions in
support of the Paris Agreement. Current point source imagers include the
GHGSat constellation and several hyperspectral and multispectral land
imaging sensors (PRISMA, Sentinel-2, Landsat-8/9, WorldView-3), with
detection thresholds in the 100–10 000 kg h−1 range that enable
monitoring of large point sources. Future area flux mappers, including
MethaneSAT, GOSAT-GW, Sentinel-5, GeoCarb, and CO2M, will increase the
capability to quantify emissions at high resolution, and the MERLIN lidar
will improve observation of the Arctic. The averaging times required by area
flux mappers to quantify regional emissions depend on pixel size, retrieval
precision, observation density, fraction of successful retrievals, and
return times in a way that varies with the spatial resolution desired. A
similar interplay applies to point source imagers between detection
threshold, spatial coverage, and return time, defining an observing system
completeness. Expanding constellations of point source imagers including
GHGSat and Carbon Mapper over the coming years will greatly improve
observing system completeness for point sources through dense spatial
coverage and frequent return times.
36 citations
TL;DR: In this paper , a basin-wide airborne survey of O&G extraction and transportation activities in the New Mexico Permian Basin, spanning 35,923 km2, 26,292 active wells, and over 15,000 km of natural gas pipelines using an independently validated hyperspectral methane point source detection and quantification system was deployed.
Abstract: Limiting emissions of climate-warming methane from oil and gas (O&G) is a major opportunity for short-term climate benefits. We deploy a basin-wide airborne survey of O&G extraction and transportation activities in the New Mexico Permian Basin, spanning 35 923 km2, 26 292 active wells, and over 15 000 km of natural gas pipelines using an independently validated hyperspectral methane point source detection and quantification system. The airborne survey repeatedly visited over 90% of the active wells in the survey region throughout October 2018 to January 2020, totaling approximately 98 000 well site visits. We estimate total O&G methane emissions in this area at 194 (+72/-68, 95% CI) metric tonnes per hour (t/h), or 9.4% (+3.5%/-3.3%) of gross gas production. 50% of observed emissions come from large emission sources with persistence-averaged emission rates over 308 kg/h. The fact that a large sample size is required to characterize the heavy tail of the distribution emphasizes the importance of capturing low-probability, high-consequence events through basin-wide surveys when estimating regional O&G methane emissions.
36 citations
TL;DR: In this article , the authors combine three complementary satellite data sets to survey single methane emission sources on the west coast of Turkmenistan, one of the largest methane hotspots in the world.
Abstract: Reduction of fossil fuel-related methane emissions has been identified as an essential means for climate change mitigation, but emission source identification remains elusive for most oil and gas production basins in the world. We combine three complementary satellite data sets to survey single methane emission sources on the west coast of Turkmenistan, one of the largest methane hotspots in the world. We found 29 different emitters, with emission rates >1800 kg/h, active in the 2017–2020 time period, although older satellite data show that this type of emission has been occurring for decades. We find that all sources are linked to extraction fields mainly dedicated to crude oil production, where 24 of them are inactive flares venting gas. The analysis of time series suggests a causal relationship between the decrease in flaring and the increase in venting. At the regional level, 2020 shows a substantial increase in the number of methane plume detections concerning previous years. Our results suggest that these large venting point sources represent a key mitigation opportunity as they emanate from human-controlled facilities, and that new satellite methods promise a revolution in the detection and monitoring of methane point emissions worldwide.
31 citations
TL;DR: This article used a decade-long dataset (2010-2019) of satellite observations of methane to show that tropical terrestrial emissions explain more than 80% of the observed changes in the global atmospheric methane growth rate over this period.
Abstract: Large variations in the growth of atmospheric methane, a prominent greenhouse gas, are driven by a diverse range of anthropogenic and natural emissions and by loss from oxidation by the hydroxyl radical. We used a decade-long dataset (2010-2019) of satellite observations of methane to show that tropical terrestrial emissions explain more than 80% of the observed changes in the global atmospheric methane growth rate over this period. Using correlative meteorological analyses, we show strong seasonal correlations (r = 0.6-0.8) between large-scale changes in sea surface temperature over the tropical oceans and regional variations in methane emissions (via changes in rainfall and temperature) over tropical South America and tropical Africa. Existing predictive skill for sea surface temperature variations could therefore be used to help forecast variations in global atmospheric methane.
28 citations
TL;DR: In this paper , the authors quantify changes in methane sources and in its atmospheric sink in 2020 compared with 2019, and find that globally, total anthropogenic emissions decreased by 1.2 ± 0.4 parts per billion per year in 2020 despite a probable decrease in anthropogenic methane emissions during COVID-19 lockdowns.
Abstract: Atmospheric methane growth reached an exceptionally high rate of 15.1 ± 0.4 parts per billion per year in 2020 despite a probable decrease in anthropogenic methane emissions during COVID-19 lockdowns1. Here we quantify changes in methane sources and in its atmospheric sink in 2020 compared with 2019. We find that, globally, total anthropogenic emissions decreased by 1.2 ± 0.1 teragrams of methane per year (Tg CH4 yr-1), fire emissions decreased by 6.5 ± 0.1 Tg CH4 yr-1 and wetland emissions increased by 6.0 ± 2.3 Tg CH4 yr-1. Tropospheric OH concentration decreased by 1.6 ± 0.2 per cent relative to 2019, mainly as a result of lower anthropogenic nitrogen oxide (NOx) emissions and associated lower free tropospheric ozone during pandemic lockdowns2. From atmospheric inversions, we also infer that global net emissions increased by 6.9 ± 2.1 Tg CH4 yr-1 in 2020 relative to 2019, and global methane removal from reaction with OH decreased by 7.5 ± 0.8 Tg CH4 yr-1. Therefore, we attribute the methane growth rate anomaly in 2020 relative to 2019 to lower OH sink (53 ± 10 per cent) and higher natural emissions (47 ± 16 per cent), mostly from wetlands. In line with previous findings3,4, our results imply that wetland methane emissions are sensitive to a warmer and wetter climate and could act as a positive feedback mechanism in the future. Our study also suggests that nitrogen oxide emission trends need to be taken into account when implementing the global anthropogenic methane emissions reduction pledge5.
26 citations
TL;DR: In this article , the authors used satellite methane observations from the Tropospheric Monitoring Instrument (TROPOMI), for May 2018 to February 2020, to quantify methane emissions from individual oil and natural gas (O/G) basin in the US and Canada using a high-resolution (∼25 km) atmospheric inverse analysis.
Abstract: Abstract. We use satellite methane observations from the
Tropospheric Monitoring Instrument (TROPOMI), for May 2018 to February 2020,
to quantify methane emissions from individual oil and natural gas (O/G)
basins in the US and Canada using a high-resolution (∼25 km)
atmospheric inverse analysis. Our satellite-derived emission estimates show
good consistency with in situ field measurements (R=0.96) in 14 O/G basins distributed across the US and Canada. Aggregating our results to the
national scale, we obtain O/G-related methane emission estimates of
12.6±2.1 Tg a−1 for the US and 2.2±0.6 Tg a−1 for
Canada, 80 % and 40 %, respectively, higher than the national inventories reported to the United Nations. About 70 % of the discrepancy in the US Environmental
Protection Agency (EPA) inventory can be attributed to five O/G basins, the Permian, Haynesville, Anadarko, Eagle Ford, and Barnett basins, which in total account for 40 % of US emissions. We show more generally that our TROPOMI inversion framework can
quantify methane emissions exceeding 0.2–0.5 Tg a−1 from individual O/G
basins, thus providing an effective tool for monitoring methane emissions
from large O/G basins globally.
25 citations
TL;DR: In this paper , the authors explore the necessary planetary context for methane to be a persuasive biosignature and assess whether, and in what planetary environments, abiotic sources of methane could result in false positive scenarios.
Abstract: Significance Astronomers will soon begin searching for biosignatures, atmospheric gases or surface features produced by life, on potentially habitable planets. Since methane is the only biosignature that the James Webb Space Telescope could readily detect in terrestrial atmospheres, it is imperative to understand methane biosignatures to contextualize these upcoming observations. We explore the necessary planetary context for methane to be a persuasive biosignature and assess whether, and in what planetary environments, abiotic sources of methane could result in false-positive scenarios. With these results, we provide a tentative framework for assessing methane biosignatures. If life is abundant in the universe, then with the correct planetary context, atmospheric methane may be the first detectable indication of life beyond Earth.
16 citations
TL;DR: This paper used a decade-long dataset (2010-2019) of satellite observations of methane to show that tropical terrestrial emissions explain more than 80% of the observed changes in the global atmospheric methane growth rate over this period.
Abstract: Large variations in the growth of atmospheric methane, a prominent greenhouse gas, are driven by a diverse range of anthropogenic and natural emissions and by loss from oxidation by the hydroxyl radical. We used a decade-long dataset (2010-2019) of satellite observations of methane to show that tropical terrestrial emissions explain more than 80% of the observed changes in the global atmospheric methane growth rate over this period. Using correlative meteorological analyses, we show strong seasonal correlations (r = 0.6-0.8) between large-scale changes in sea surface temperature over the tropical oceans and regional variations in methane emissions (via changes in rainfall and temperature) over tropical South America and tropical Africa. Existing predictive skill for sea surface temperature variations could therefore be used to help forecast variations in global atmospheric methane.
16 citations
TL;DR: In this article , the authors investigate methane sources and fates in the East China Sea and map global MOx rates in shallow waters by training machine-learning models, showing that methane is produced during methylphosphonate decomposition under phosphate-limiting conditions and sedimentary release is also source of methane.
Abstract: Methane is supersaturated in surface seawater and shallow coastal waters dominate global ocean methane emissions to the atmosphere. Aerobic methane oxidation (MOx) can reduce atmospheric evasion, but the magnitude and control of MOx remain poorly understood. Here we investigate methane sources and fates in the East China Sea and map global MOx rates in shallow waters by training machine-learning models. We show methane is produced during methylphosphonate decomposition under phosphate-limiting conditions and sedimentary release is also source of methane. High MOx rates observed in these productive coastal waters are correlated with methanotrophic activity and biomass. By merging the measured MOx rates with methane concentrations and other variables from a global database, we predict MOx rates and estimate that half of methane, amounting to 1.8 ± 2.7 Tg, is consumed annually in near-shore waters (<50 m), suggesting that aerobic methanotrophy is an important sink that significantly constrains global methane emissions.
15 citations
TL;DR: In this article , an atmospheric inversion framework based on TM5-4DVAR is proposed to estimate source-specific methane emissions, and the authors present global emission estimates from this framework for the period 1999-2016.
Abstract: Abstract. We have constructed an atmospheric inversion framework based on TM5-4DVAR to jointly assimilate measurements of methane and δ13C of methane in order to estimate source-specific methane emissions. Here we present global emission estimates from this framework for the period 1999–2016. We assimilate a newly constructed, multi-agency database of CH4 and δ13C measurements. We find that traditional CH4-only atmospheric inversions are unlikely to estimate emissions consistent with atmospheric δ13C data, and assimilating δ13C data is necessary to derive emissions consistent with both measurements. Our framework attributes ca. 85 % of the post-2007 growth in atmospheric methane to microbial sources, with about half of that coming from the tropics between 23.5∘ N and 23.5∘ S. This contradicts the attribution of the recent growth in the methane budget of the Global Carbon Project (GCP). We find that the GCP attribution is only consistent with our top-down estimate in the absence of δ13C data. We find that at global and continental scales, δ13C data can separate microbial from fossil methane emissions much better than CH4 data alone, and at smaller scales this ability is limited by the current δ13C measurement coverage. Finally, we find that the largest uncertainty in using δ13C data to separate different methane source types comes from our knowledge of atmospheric chemistry, specifically the distribution of tropospheric chlorine and the isotopic discrimination of the methane sink.
TL;DR: In this paper , the authors report on the promising potential of the WorldView-3 (WV-3) satellite mission for methane mapping, which relies on its unique very high spatial resolution (up to 3.7 m) data in the shortwave infrared part of the spectrum, which is complemented by a good spectral sampling of the methane absorption feature at 2300 nm and a high signal to noise ratio.
Abstract: Abstract. The detection of methane emissions from industrial activities can help enable effective climate change mitigation strategies. These industrial emissions, such as from oil and gas (O&G) extraction and coal mining, typically occur as large plumes of highly concentrated gas. Different satellite missions have recently shown the potential to map such methane plumes from space. In this work, we report on the promising potential of the WorldView-3 (WV-3) satellite mission for methane mapping. This relies on its unique very high spatial resolution (up to 3.7 m) data in the shortwave infrared part of the spectrum, which is complemented by a good spectral sampling of the methane absorption feature at 2300 nm and a high signal to noise ratio. The proposed retrieval methodology is based on the calculation of methane concentration enhancements from pixel-wise estimates of methane transmittance at WV-3 SWIR band 7 (2235–2285 nm), which is positioned at a highly-sensitive methane absorption region. A sensitivity analysis based on end-to-end simulations has helped to understand retrieval errors and detection limits. The results have shown the good performance of WV-3 for methane mapping, especially over bright and homogeneous areas. The potential of WV-3 for methane mapping has been further tested with real data, which has led to the detection of 26 independent point emissions over different methane hotspot regions, such as O&G extraction fields in Algeria and Turkmenistan, and the Shanxi coal mining region in China. In particular, the detection of very small leaks (< 100 kg h−1) from oil pipelines in Turkmenistan shows the unique capability of WV-3 for mapping industrial methane emissions from space. The mission includes pointing capabilities that allow for a daily revisit over these oil pipelines or other critical infrastructure.
TL;DR: In this article , the authors report a trend of increasing methane emissions for the early summer months of June and July at a permafrost site in the Lena River Delta, on the basis of the longest set of eddy covariance methane flux data in the Arctic.
Abstract: Abstract While increasing methane emissions from thawing permafrost are anticipated to be a major climate feedback, no observational evidence for such an increase has previously been documented in the literature. Here we report a trend of increasing methane emissions for the early summer months of June and July at a permafrost site in the Lena River Delta, on the basis of the longest set of eddy covariance methane flux data in the Arctic. Along with a strong air temperature rise of 0.3 ± 0.1 °C yr −1 in June, which corresponds to an earlier warming of 11 d, the methane emissions in June and July have increased by roughly 1.9 ± 0.7% yr −1 since 2004. Although the tundra’s maximum source strength in August has not yet changed, this increase in early summer methane emissions shows that atmospheric warming has begun to considerably affect the methane flux dynamics of permafrost-affected ecosystems in the Arctic.
TL;DR: In this article , a new, methane emissions-driven version of the UK Earth System Model (UKESM1) was used to simulate a zero anthropogenic methane emissions scenario (ZAME) in order to attribute the role of anthropogenic Methane emissions on the Earth system and bracket the potential for theoretical maximum mitigation.
Abstract: Abstract Mitigation of greenhouse gas emissions is crucial for achieving the goals of the Paris climate agreement. One key gas is methane, whose representation in most climate models is limited by using prescribed surface concentrations. Here we use a new, methane emissions-driven version of the UK Earth System Model (UKESM1) and simulate a zero anthropogenic methane emissions scenario (ZAME) in order to (i) attribute the role of anthropogenic methane emissions on the Earth system and (ii) bracket the potential for theoretical maximum mitigation. We find profound, rapid and sustained impacts on atmospheric composition and climate, compared to a counterfactual projection (SSP3-7.0, the ’worst case’ scenario for methane). In ZAME, methane declines to below pre-industrial levels within 12 years and global surface ozone decreases to levels seen in the 1970s. By 2050, 690,000 premature deaths per year and 1° of warming can be attributed to anthropogenic methane in SSP3-7.0. This work demonstrates the significant maximum potential of methane emissions reductions, and their air-quality co-benefits, but also reiterates the need for action on carbon dioxide (CO 2 ) emissions. We show that a methane emissions-driven treatment is essential for simulating the full Earth system impacts and feedbacks of methane emissions changes.
TL;DR: In this article , the column-averaged dry air mixing ratio of CH4 (abbreviated as XCH4 hereafter) was collected from TROPOMI for the period from 2018 to 2021, to study spatial distribution and temporal change of atmospheric CH4 concentration.
Abstract: Methane is the second most important greenhouse gas after carbon dioxide. The intensity and distribution of methane source/sink in China are unknown. We collected the column-averaged dry air mixing ratio of CH4 (abbreviated as XCH4 hereafter) from TROPOMI for the period from 2018 to 2021, to study spatial distribution and temporal change of atmospheric CH4 concentration, providing clues and foundations for understanding the source/sink in China. It was found that the distribution of XCH4 is roughly high in the East, low in the West, high in the South and low in the North. Additionally, an evidently positive linear relationship between XCH4 and population density was witnessed, suggesting anthropogenic emissions may account for a large portion of total methane emissions. XCH4 exhibits evident seasonal characteristics, with the peak in summer and trough in winter, regardless of the different regions. Moreover, we used XCH4 anomalies to identify the emission sources and found its great potential in the detection of methane emission from mining plants, landfill, rice fields and even geological fracture zones.
TL;DR: In this article , the authors conduct a global inverse analysis of 2019-2020 satellite observations of atmospheric methane to analyze the combination of sources and sinks driving this surge, finding that 31 Tg a−1 increased from 2019 to 2020, representing a 36 Tg −1 forcing on the methane budget away from steady state.
Abstract: Atmospheric methane mixing ratio rose by 15 ppbv between 2019 and 2020, the fastest growth rate on record. We conduct a global inverse analysis of 2019–2020 Greenhouse Gases Observing Satellite observations of atmospheric methane to analyze the combination of sources and sinks driving this surge. The imbalance between sources and sinks of atmospheric methane increased by 31 Tg a−1 from 2019 to 2020, representing a 36 Tg a−1 forcing (direct changes in methane emissions and OH concentrations) on the methane budget away from steady state. 86% of the forcing in the base inversion is from increasing emissions (82 ± 18% in the nine-member inversion ensemble), and only 14% is from decrease in tropospheric OH. Half of the increase in emissions is from Africa (15 Tg a−1) and appears to be driven by wetland inundation. There is also a large relative increase in emissions from Canada and Alaska (4.8 Tg a−1, 24%) that could be driven by temperature sensitivity of boreal wetland emissions.
TL;DR: In this paper , the first airborne measurements of CH4 sampled over three wetland areas in Zambia were used to derive emission fluxes, and three independent approaches to flux quantification from airborne measurements were used: airborne mass balance, airborne eddy-covariance, and an atmospheric inversion.
Abstract: Methane (CH4) is a potent greenhouse gas with a warming potential 84 times that of carbon dioxide (CO2) over a 20-year period. Atmospheric CH4 concentrations have been rising since the 19th century but the cause of large increases post-2007 are disputed. Tropical wetlands are thought to account for ∼20% of global CH4 emissions, but African tropical wetlands are understudied and their contribution is uncertain. In this work, we use the first airborne measurements of CH4 sampled over three wetland areas in Zambia to derive emission fluxes. Three independent approaches to flux quantification from airborne measurements were used: airborne mass balance, airborne eddy-covariance, and an atmospheric inversion. Measured emissions (ranging from 5–28 mg m-2 hr-1) were found to be an order of magnitude greater than those simulated by land surface models (ranging from 0.6–3.9 mg m-2 hr-1), suggesting much greater emissions from tropical wetlands than currently accounted for. The prevalence of such underestimated CH4 sources may necessitate additional reductions in anthropogenic greenhouse gas emissions to keep global warming below a threshold of 2 °C above pre-industrial levels.
TL;DR: In this article , a process-based biogeochemistry model was used to calculate the stable carbon isotopic composition of global wetland methane emissions, and the model showed improved resolution of regional, latitudinal and global variations in isotopic compositions of wetland emissions.
Abstract: Abstract Atmospheric concentrations of methane, a powerful greenhouse gas, have strongly increased since 2007. Measurements of stable carbon isotopes of methane can constrain emissions if the isotopic compositions are known; however, isotopic compositions of methane emissions from wetlands are poorly constrained despite their importance. Here, we use a process-based biogeochemistry model to calculate the stable carbon isotopic composition of global wetland methane emissions. We estimate a mean global signature of −61.3 ± 0.7‰ and find that tropical wetland emissions are enriched by ~11‰ relative to boreal wetlands. Our model shows improved resolution of regional, latitudinal and global variations in isotopic composition of wetland emissions. Atmospheric simulation scenarios with the improved wetland isotopic composition suggest that increases in atmospheric methane since 2007 are attributable to rising microbial emissions. Our findings substantially reduce uncertainty in the stable carbon isotopic composition of methane emissions from wetlands and improve understanding of the global methane budget.
Netherlands Institute for Space Research1, Environmental Defense Fund2, North Carolina State University3, Harvard University4, Central South University5, Southern Marine Science and Engineering Guangdong Laboratory6, Pennsylvania State University7, Mount Sinai Health System8, VU University Amsterdam9
TL;DR: In this article , the authors quantify weekly methane emissions at 0.25°×0.3125° (approximately 25×25 km2) resolution from the Permian Basin, the largest oil production basin in the United States, by inverse analysis of satellite observations from the TROPOspheric Monitoring Instrument (TROPOMI) from May 2018 to October 2020.
Abstract: Abstract. We quantify weekly methane emissions at 0.25°×0.3125° (≈25×25 km2) resolution from the Permian Basin, the largest oil production basin in the United States, by inverse analysis of satellite observations from the TROPOspheric Monitoring Instrument (TROPOMI) from May 2018 to October 2020. The mean oil and gas emission from the region (± standard deviation of weekly estimates) was 3.7 ± 0.9 Tg a-1, higher than previous TROPOMI inversion estimates that may have used too-low prior emissions or biased background assumptions. We find strong week-to-week variability in emissions superimposed on longer-term trends, and these are consistent with independent inferences of temporal emission variability from tower, aircraft, and multispectral satellite data. New well development and local natural gas spot price were significant drivers of variability in emissions over our study period, but the concurrent 50 % increase in oil and gas production was not. The methane intensity (methane emitted per unit of methane gas produced) averaged 4.6 % ± 1.3 % and steadily decreased over the period from 5–6 % in 2018 to 3–4 % in 2020. While the decreasing trend suggests improvement in operator practices during the study period, methane emissions from the Permian Basin remained high, with methane intensity an order of magnitude above recent industry targets of <0.2 %. Our success in using TROPOMI satellite observations for weekly estimates of emissions from a major oil production basin shows promise for application to near-real-time monitoring in support of climate change mitigation efforts.
TL;DR: In this article , the state of the water masses of the Arctic Ocean was simulated based on a regional ice-ocean model to analyze the transport of dissolved methane on the Arctic shelves.
Abstract: Based on a regional ice-ocean model, we simulated the state of the water masses of the Arctic Ocean to analyze the transport of dissolved methane on the Arctic shelves. From 1970 to 2019, we obtained estimates of methane emissions at the Arctic seas due to the degradation of submarine permafrost and gas release at the ocean–bottom interface. The calculated annual methane flux from the Arctic shelf seas into the atmosphere did not exceed 2 Tg CH4 yr−1. We have shown that the East Siberian shelf seas make the main contribution to the total methane emissions of the region. The spatial variability of the methane fluxes into the atmosphere is primarily due to the peculiarities of the water circulation and ice conditions. Only 7% of the dissolved methane originating from sediment enters the atmosphere within the study area. Most of it appears to be transported below the surface and oxidized by microbial activity. We found that increasing periods and areas of ice-free water and decreasing ice concentration have contributed to a steady increase in methane emissions since the middle of the first decade of the current century.
TL;DR: In this article , the authors investigate through a minimalist model the response of atmospheric methane to fossil fuel displacement by hydrogen and find that CH 4 concentration may increase or decrease depending on the amount of hydrogen lost to the atmosphere and the methane emissions associated with hydrogen production.
Abstract: Abstract Hydrogen (H 2 ) is expected to play a crucial role in reducing greenhouse gas emissions. However, hydrogen losses to the atmosphere impact atmospheric chemistry, including positive feedback on methane (CH 4 ), the second most important greenhouse gas. Here we investigate through a minimalist model the response of atmospheric methane to fossil fuel displacement by hydrogen. We find that CH 4 concentration may increase or decrease depending on the amount of hydrogen lost to the atmosphere and the methane emissions associated with hydrogen production. Green H 2 can mitigate atmospheric methane if hydrogen losses throughout the value chain are below 9 ± 3%. Blue H 2 can reduce methane emissions only if methane losses are below 1%. We address and discuss the main uncertainties in our results and the implications for the decarbonization of the energy sector.
17 Jun 2022
TL;DR: In this paper , the authors use newly available methane data from the Japanese Greenhouse gases Observing SATellite (GOSAT) to estimate methane surface emissions and find statistically significant positive correlations between anomalies of tropical methane emissions and groundwater, consistent with recent studies that have highlighted a growing role for microbial sources over the tropics.
Abstract: Abstract. The global atmospheric methane growth rates reported by NOAA for 2020 and 2021 are the largest since systematic measurements began in 1983. To explore the underlying reasons for these anomalous growth rates we use newly available methane data from the Japanese Greenhouse gases Observing SATellite (GOSAT) to estimate methane surface emissions. Relative to baseline values in 2019 we see the largest annual increases in methane emissions during 2020 over Eastern Africa (13 Tg), tropical Asia (4 Tg), tropical South America (3 Tg), and temperate Eurasia (3 Tg), and the largest reductions over China (-6 Tg) and India (-2 Tg). We find comparable emission changes in 2021, relative to 2019, except for tropical and temperate South America where emissions increased to 9 Tg and 5 Tg, respectively, and tropical Asian emissions increased to 8 Tg. The elevated contributions we saw in 2020 over the western half of Africa (-5 Tg) and Europe (-3 Tg) are substantially reduced in 2021, compared to our 2019 baseline. We find statistically significant positive correlations between anomalies of tropical methane emissions and groundwater, consistent with recent studies that have highlighted a growing role for microbial sources over the tropics. Emission reductions over India and China are expected in 2020 due to the Covid-19 shutdown but continued in 2021, which we do not currently understand. Based on a sensitivity study for which we assume a conservative 5 % decrease in hydroxyl concentrations in 2020, due to reduced pollutant emissions during the Covid-19 shutdown, we find that the global increase in our a posteriori emissions in 2020 is ~22 % lower than our control calculation. We conclude therefore that most of the observed increase in atmospheric methane during 2020 and 2021 is due to increased emissions.
TL;DR: In this article , a mobile IR radiation source for the differential absorption lidar was calibrated in the informative range for methane sounding near ∼3400 nm for mid-latitude summer conditions.
Abstract: A mobile infrared (IR) differential absorption lidar designed for the study of methane in the atmosphere is described. A mobile IR radiation source for the differential absorption lidar was calibrated in the informative range for methane sounding near ∼3400 nm. Informative methane sounding wavelengths for mid-latitude summer conditions are 3428.428 nm (on-line) and 3431.708 nm (off-line), respectively. The maximum output energy in a pulse of the mobile lidar is 4.3 mJ (for on-line wavelength) and 2.5 mJ (for off-line wavelength). The lidar was in situ tested in recording the atmospheric response at calibrated sounding wavelengths and in retrieving background methane concentrations of ∼2.0 ppm along surface atmospheric sounding paths. The test results at the Basic Experimental Complex and the Fonovaya Observatory of IAO SB RAS are presented.
TL;DR: In this article , the authors trace the pathways of dissolved methane at the Eurasian continental slope and the Siberian shelf break based on data collected during the NABOS-II expedition in August-September, 2013.
Abstract: This study traces the pathways of dissolved methane at the Eurasian continental slope (ECS) and the Siberian shelf break based on data collected during the NABOS-II expedition in August-September, 2013. We focus on the sea ice-ocean interface during seasonal strong ice melt. Our analysis reveals a patchy pattern of methane supersaturation related to the atmospheric equilibrium. We argue that sea ice transports methane from the shelf and that ice melt is the process that causes the heterogeneous pattern of methane saturation in the Polar Mixed Layer (PML). We calculate the solubility capacity and find that seasonal warming of the PML reduces the CH4 storage capacity and contributes to methane supersaturation and potential sea-air flux in summer. Cooling in autumn enhances the solubility capacity in the PML once again. The shifts in the solubility capacity indicate the buffering capacity for seasonal storage of atmospheric and marine methane in the PML. We discuss specific pathways for marine methane and the storage capacity of the PML on the ECS as a sink/source for atmospheric methane and methane sources from the Siberian shelf. The potential sea-air flux of methane is calculated and intrusions of methane plumes from the PML into the Cold Halocline Layer are described.
07 Mar 2022
TL;DR: In this article , the Tropospheric Monitoring Instrument (TROPOMI) was used to quantify methane emissions from individual oil and natural gas (O/G) basins in the US and Canada using a high-resolution (~ 25 km) atmospheric inverse analysis.
Abstract: Abstract. We use satellite methane observations from the Tropospheric Monitoring Instrument (TROPOMI), from May 2018 to February 2020, to quantify methane emissions from individual oil and natural gas (O/G) basins in the US and Canada using a high-resolution (~ 25 km) atmospheric inverse analysis. Our satellite-derived emission estimates show good consistency with in-situ field measurements (R2 = 0.92) in 14 O/G basins distributed across the US and Canada. Aggregating our results to the national scale, we obtain O/G-related methane emission estimates of 12.6 ± 2.1 Tg a-1 for the US and 2.2 ± 0.6 Tg a-1 for Canada, respectively 80 % and 40 % higher than the national inventories reported to the United Nations. About 70 % of the discrepancy in the EPA inventory can be attributed to five O/G basins: the Permian, Haynesville, Anadarko, Eagle Ford and Barnett Basin, which in total account for 40 % of US emissions. We show more generally that our TROPOMI inversion framework can quantify methane emissions exceeding 0.2–0.5 Tg a-1 from individual O/G basins, thus providing an effective tool for monitoring methane emissions from large O/G basins globally.
TL;DR: In this article, the influence of environmental variables on the abundance of culturable methanotrophs (MOB), methane oxidation activity (MOA) and methane production activity (MPA) during a grow-out cycle in zero-exchange shrimp pond growing whiteleg shrimp, Litopenaeus vannamei.
TL;DR: Monteiro et al. as discussed by the authors described the instrumentation, calibration, and uncertainty of the ground-based, in situ, cavity ring down spectroscopy (CRDS) greenhouse gas (GHG) measurements deployed in the Permian basin.
Abstract: Abstract. We describe the instrumentation, calibration, and uncertainty of the network of ground-based, in situ, cavity ring down spectroscopy (CRDS) greenhouse gas (GHG) measurements deployed in the Permian basin. The primary goal of the network is to be used in conjunction with atmospheric transport modeling to determine methane emissions of the Delaware sub-basin of the Permian Basin oil and natural gas extraction area in Texas and New Mexico. Four of the measurements are based on tall communications towers, while one is on a building on a mountain ridge, with the recent addition of a small tower at that site. Although methane (CH4) is the primary specie of interest, carbon dioxide (CO2), hydrogen sulfide (H2S), and the isotopic ratio of methane (δ13CH4) are also reported for a subset of the sites. Measurements were reported following WMO X2004A scale for CH4, and the WMO X2019 scale for CO2. CRDS instruments were calibrated for CH4 and CO2 in laboratory prior deployment. For H2S, data was offset-corrected using the minimum 40-min running mean value of the day, and for δ13CH4, calibrations were based on laboratory data. We describe the characteristics of the data set with a set of illustrative analyses. Methane and carbon dioxide showed strong seasonality, with a well-defined diurnal cycle during the summer, which was opposed to the winter, when a diurnal cycle was absent. CH4 enhancements to the background, during the winter, are up to twice the summer values, which is attributed to the changes in boundary layer depth and wind speed. The largest CH4 enhancements occurred when winds blow from the center of the Delaware sub-basin, where most of the methane emissions come from. The magnitude of enhancements of CO2 did not present seasonality. H2S enhancements indicated a potential source northeast of the tower where the inlet is installed. Isotopic ratios of methane indicated that oil and natural gas extraction is the source of local methane in the region. The hourly-averaged data, starting on 1 March 2020 and described in this paper, are archived at The Pennsylvania State University Data Commons at https://doi.org/10.26208/98y5-t941 (Monteiro et al., 2021).
TL;DR: In this article , mobile infrared cavity ringdown spectrometry, drone-mounted meteorological sensors and tunable diode laser spectrometers were deployed to measure methane emissions from two landfills in the Southeast Michigan ozone nonattainment area during the Michigan-Ontario Ozone Source Experiment (MOOSE).
Abstract: Municipal solid waste landfills are significant sources of atmospheric methane, the second most important greenhouse gas after carbon dioxide. Large emissions of methane from landfills contribute not only to global climate change, but also to local ozone formation due to the enhancement of radical chain lengths in atmospheric reactions of volatile organic compounds and nitrogen oxides. Several advanced techniques were deployed to measure methane emissions from two landfills in the Southeast Michigan ozone nonattainment area during the Michigan–Ontario Ozone Source Experiment (MOOSE). These techniques included mobile infrared cavity ringdown spectrometry, drone-mounted meteorological sensors and tunable diode laser spectrometry, estimation of total landfill emissions of methane based on flux plane measurements, and Gaussian plume inverse modeling of distributed methane emissions in the presence of complex landfill terrain. The total methane emissions measured at the two landfills were of the order of 500 kg/h, with an uncertainty of around 50%. The results indicate that both landfill active faces and leaking gas collection systems are important sources of methane emissions.
TL;DR: In this paper , the authors present empirical observations of hitherto undocumented, widespread and extensive methane and oil release from geological reservoirs to the Arctic Ocean, and demonstrate that such persistent, geologically controlled, natural hydrocarbon release may be characteristic of formerly glaciated hydrocarbon-bearing basins which are common across polar continental shelves.
Abstract: Abstract Parceling the anthropogenic and natural (geological) sources of fossil methane in the atmosphere remains problematic due to a lack of distinctive chemical markers for their discrimination. In this light, understanding the distribution and contribution of potential geological methane sources is important. Here we present empirical observations of hitherto undocumented, widespread and extensive methane and oil release from geological reservoirs to the Arctic Ocean. Methane fluxes from >7000 seeps significantly deplete in seawater, but nevertheless reach the sea surface and may transfer to the air. Oil slick emission spots and gas ebullition are persistent across multi-year observations and correlate to formerly glaciated geological structures, which have experienced km-scale glacial erosion that has left hydrocarbon reservoirs partially uncapped since the last deglaciation ~15,000 years ago. Such persistent, geologically controlled, natural hydrocarbon release may be characteristic of formerly glaciated hydrocarbon-bearing basins which are common across polar continental shelves, and could represent an underestimated source of natural fossil methane within the global carbon cycle.
TL;DR: Wang et al. as mentioned in this paper detected spatial and temporal variations of atmospheric CH4 concentrations in China during 2003-2021 based on CH4 column-averaged dry-air mole fraction (XCH4) products from three satellites, namely, Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY), Greenhouse Gases Observing Satellite (GOSAT), and Copernicus Sentinel-5 Precursor (S5P).
Abstract: Atmospheric methane (CH4) is an important greenhouse gas that can reflect variations of CH4 emissions and sinks. This study aimed to detect spatial and temporal variations of atmospheric CH4 concentrations in China during 2003–2021 based on CH4 column-averaged dry-air mole fraction (XCH4) products from three satellites, namely, Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY), Greenhouse Gases Observing Satellite (GOSAT), and Copernicus Sentinel-5 Precursor (S5P). The results revealed that XCH4 observed from three satellites showed high agreement in spatiotemporal variations and demonstrated good consistency with ground station measurements. The correlation coefficients (r) between the three satellites were 0.72 and 0.73, and the correlation coefficients for the ground stations were 0.79, 0.66, 0.03, 0.21, 0.70, and 0.80. The spatial distribution of XCH4 in China was generally high in the east and low in the west and close to that of CH4 emissions, indicating that CH4 emission sources dominated the spatial variations of atmospheric XCH4. From 2003 to 2006, XCH4 remained stable with an annual growth rate of 0.51 ppb·yr−1 and then abruptly increased with an overall growth rate of 6.96 ppb·yr−1. There were obvious seasonal changes in XCH4, with peaks in autumn and summer and nadir in winter and spring. These seasonal variations of XCH4 were related to CH4 emissions from rice planting. Rice cultivation areas generally had high XCH4 concentrations, and the growth cycle of rice plants significantly contributed to seasonal variations of XCH4 in the main rice planting areas. These results provide scientific data that could encourage decision-makers to enact policies and processes to reduce methane emissions.