Articles | Volume 16, issue 15
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Ideas and perspectives: is shale gas a major driver of recent increase in global atmospheric methane?
Robert W. Howarth
Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
Related subject area
Biogeochemistry: Greenhouse GasesMeteorological responses of carbon dioxide and methane fluxes in the terrestrial and aquatic ecosystems of a subarctic landscapeCarbon emission and export from the Ket River, western SiberiaEvaluation of wetland CH4 in the Joint UK Land Environment Simulator (JULES) land surface model using satellite observationsGreenhouse gas fluxes in mangrove forest soil in an Amazon estuaryTemporal patterns and drivers of CO2 emission from dry sediments in a groyne field of a large riverEffects of water table level and nitrogen deposition on methane and nitrous oxide emissions in an alpine peatlandHighest methane concentrations in an Arctic river linked to local terrestrial inputsSeasonal study of the small-scale variability in dissolved methane in the western Kiel Bight (Baltic Sea) during the European heatwave in 2018Trace gas fluxes from tidal salt marsh soils: implications for carbon–sulfur biogeochemistrySpatial and temporal variation in δ13C values of methane emitted from a hemiboreal mire: methanogenesis, methanotrophy, and hysteresisIntercomparison of methods to estimate gross primary production based on CO2 and COS flux measurementsLateral carbon export has low impact on the net ecosystem carbon balance of a polygonal tundra catchmentThe effect of static chamber base on N2O flux in drip irrigationControls on autotrophic and heterotrophic respiration in an ombrotrophic bogEpisodic N2O emissions following tillage of a legume–grass cover crop mixtureVariation in CO2 and CH4 fluxes among land cover types in heterogeneous Arctic tundra in northeastern SiberiaResponse of vegetation and carbon fluxes to brown lemming herbivory in northern AlaskaSources of nitrous oxide and the fate of mineral nitrogen in subarctic permafrost peat soilsData-based estimates of interannual sea–air CO2 flux variations 1957–2020 and their relation to environmental driversEvaluating alternative ebullition models for predicting peatland methane emission and its pathways via data–model fusionExcess soil moisture and fresh carbon input are prerequisites for methane production in podzolic soilLow biodegradability of particulate organic carbon mobilized from thaw slumps on the Peel Plateau, NT, and possible chemosynthesis and sorption effectsGrazing enhances carbon cycling but reduces methane emission during peak growing season in the Siberian Pleistocene Park tundra siteIdeas and perspectives: Enhancing research and monitoring of carbon pools and land-to-atmosphere greenhouse gases exchange in developing countriesIgnoring carbon emissions from thermokarst ponds results in overestimation of tundra net carbon uptakeQuantification of potential methane emissions associated with organic matter amendments following oxic-soil inundationAssessing the spatial and temporal variability of greenhouse gas emissions from different configurations of on-site wastewater treatment system using discrete and continuous gas flux measurementDimethylated sulfur compounds in the Peruvian upwelling systemPartitioning carbon sources between wetland and well-drained ecosystems to a tropical first-order stream – implications for carbon cycling at the watershed scale (Nyong, Cameroon)Extreme events driving year-to-year differences in gross primary productivity across the USMethane gas emissions from savanna fires: what analysis of local burning regimes in a working West African landscape tell usMethane in Zackenberg Valley, NE Greenland: multidecadal growing season fluxes of a high-Arctic tundraField-scale CH4 emission at a subarctic mire with heterogeneous permafrost thaw statusEvaluation of denitrification and decomposition from three biogeochemical models using laboratory measurements of N2, N2O and CO2Temporal trends in methane emissions from a small eutrophic reservoir: the key role of a spring burstGreenhouse gases emissions from riparian wetlands: an example from the Inner Mongolia grassland region in ChinaVariability of North Atlantic CO2 fluxes for the 2000–2017 period estimated from atmospheric inverse analysesEffects of clear-fell harvesting on soil CO2, CH4, and N2O fluxes in an upland Sitka spruce stand in EnglandConventional subsoil irrigation techniques do not lower carbon emissions from drained peat meadowsDifferent responses of ecosystem CO2 and N2O emissions and CH4 uptake to seasonally asymmetric warming in an alpine grassland of the TianshanThe role of termite CH4 emissions on the ecosystem scale: a case study in the Amazon rainforestBiogeochemical and plant trait mechanisms drive enhanced methane emissions in response to whole-ecosystem warmingA decade of dimethyl sulfide (DMS), dimethylsulfoniopropionate (DMSP) and dimethyl sulfoxide (DMSO) measurements in the southwestern Baltic SeaMethane dynamics in three different Siberian water bodies under winter and summer conditionsTopography-based statistical modelling reveals high spatial variability and seasonal emission patches in forest floor methane fluxTechnical note: CO2 is not like CH4 – limits of and corrections to the headspace method to analyse pCO2 in fresh waterComparison of greenhouse gas fluxes from tropical forests and oil palm plantations on mineral soilAre there memory effects on greenhouse gas emissions (CO2, N2O and CH4) following grassland restoration?Intraseasonal variability of greenhouse gas emission factors from biomass burning in the Brazilian CerradoEvaluating stream CO2 outgassing via drifting and anchored flux chambers in a controlled flume experiment
Lauri Heiskanen, Juha-Pekka Tuovinen, Henriikka Vekuri, Aleksi Räsänen, Tarmo Virtanen, Sari Juutinen, Annalea Lohila, Juha Mikola, and Mika Aurela
Biogeosciences, 20, 545–572,Short summary
We measured and modelled the CO2 and CH4 fluxes of the terrestrial and aquatic ecosystems of the subarctic landscape for 2 years. The landscape was an annual CO2 sink and a CH4 source. The forest had the largest contribution to the landscape-level CO2 sink and the peatland to the CH4 emissions. The lakes released 24 % of the annual net C uptake of the landscape back to the atmosphere. The C fluxes were affected most by the rainy peak growing season of 2017 and the drought event in July 2018.
Artem G. Lim, Ivan V. Krickov, Sergey N. Vorobyev, Mikhail A. Korets, Sergey Kopysov, Liudmila S. Shirokova, Jan Karlsson, and Oleg S. Pokrovsky
Biogeosciences, 19, 5859–5877,Short summary
In order to quantify C transport and emission and main environmental factors controlling the C cycle in Siberian rivers, we investigated the largest tributary of the Ob River, the Ket River basin, by measuring spatial and seasonal variations in carbon CO2 and CH4 concentrations and emissions together with hydrochemical analyses. The obtained results are useful for large-scale modeling of C emission and export fluxes from permafrost-free boreal rivers of an underrepresented region of the world.
Robert J. Parker, Chris Wilson, Edward Comyn-Platt, Garry Hayman, Toby R. Marthews, A. Anthony Bloom, Mark F. Lunt, Nicola Gedney, Simon J. Dadson, Joe McNorton, Neil Humpage, Hartmut Boesch, Martyn P. Chipperfield, Paul I. Palmer, and Dai Yamazaki
Biogeosciences, 19, 5779–5805,Short summary
Wetlands are the largest natural source of methane, one of the most important climate gases. The JULES land surface model simulates these emissions. We use satellite data to evaluate how well JULES reproduces the methane seasonal cycle over different tropical wetlands. It performs well for most regions; however, it struggles for some African wetlands influenced heavily by river flooding. We explain the reasons for these deficiencies and highlight how future development will improve these areas.
Saúl Edgardo Martínez Castellón, José Henrique Cattanio, José Francisco Berrêdo, Marcelo Rollnic, Maria de Lourdes Ruivo, and Carlos Noriega
Biogeosciences, 19, 5483–5497,Short summary
We seek to understand the influence of climatic seasonality and microtopography on CO2 and CH4 fluxes in an Amazonian mangrove. Topography and seasonality had a contrasting influence when comparing the two gas fluxes: CO2 fluxes were greater in high topography in the dry period, and CH4 fluxes were greater in the rainy season in low topography. Only CO2 fluxes were correlated with soil organic matter, the proportion of carbon and nitrogen, and redox potential.
Matthias Koschorreck, Klaus Holger Knorr, and Lelaina Teichert
Biogeosciences, 19, 5221–5236,Short summary
At low water levels, parts of the bottom of rivers fall dry. These beaches or mudflats emit the greenhouse gas carbon dioxide (CO2) to the atmosphere. We found that those emissions are caused by microbial reactions in the sediment and that they change with time. Emissions were influenced by many factors like temperature, water level, rain, plants, and light.
Wantong Zhang, Zhengyi Hu, Joachim Audet, Thomas A. Davidson, Enze Kang, Xiaoming Kang, Yong Li, Xiaodong Zhang, and Jinzhi Wang
Biogeosciences, 19, 5187–5197,Short summary
This work focused on the CH4 and N2O emissions from alpine peatlands in response to the interactive effects of altered water table levels and increased nitrogen deposition. Across the 2-year mesocosm experiment, nitrogen deposition showed nonlinear effects on CH4 emissions and linear effects on N2O emissions, and these N effects were associated with the water table levels. Our results imply the future scenario of strengthened CH4 and N2O emissions from an alpine peatland.
Karel Castro-Morales, Anna Canning, Sophie Arzberger, Will A. Overholt, Kirsten Küsel, Olaf Kolle, Mathias Göckede, Nikita Zimov, and Arne Körtzinger
Biogeosciences, 19, 5059–5077,Short summary
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.
Sonja Gindorf, Hermann W. Bange, Dennis Booge, and Annette Kock
Biogeosciences, 19, 4993–5006,Short summary
Methane is a climate-relevant greenhouse gas which is emitted to the atmosphere from coastal areas such as the Baltic Sea. We measured the methane concentration in the water column of the western Kiel Bight. Methane concentrations were higher in September than in June. We found no relationship between the 2018 European heatwave and methane concentrations. Our results show that the methane distribution in the water column is strongly affected by temporal and spatial variabilities.
Margaret Capooci and Rodrigo Vargas
Biogeosciences, 19, 4655–4670,Short summary
Tidal salt marsh soil emits greenhouse gases, as well as sulfur-based gases, which play roles in global climate but are not well studied as they are difficult to measure. Traditional methods of measuring these gases worked relatively well for carbon dioxide, but less so for methane, nitrous oxide, carbon disulfide, and dimethylsulfide. High variability of trace gases complicates the ability to accurately calculate gas budgets and new approaches are needed for monitoring protocols.
Janne Rinne, Patryk Łakomiec, Patrik Vestin, Joel D. White, Per Weslien, Julia Kelly, Natascha Kljun, Lena Ström, and Leif Klemedtsson
Biogeosciences, 19, 4331–4349,Short summary
The study uses the stable isotope 13C of carbon in methane to investigate the origins of spatial and temporal variation in methane emitted by a temperate wetland ecosystem. The results indicate that methane production is more important for spatial variation than methane consumption by micro-organisms. Temporal variation on a seasonal timescale is most likely affected by more than one driver simultaneously.
Kukka-Maaria Kohonen, Roderick Dewar, Gianluca Tramontana, Aleksanteri Mauranen, Pasi Kolari, Linda M. J. Kooijmans, Dario Papale, Timo Vesala, and Ivan Mammarella
Biogeosciences, 19, 4067–4088,Short summary
Four different methods for quantifying photosynthesis (GPP) at ecosystem scale were tested, of which two are based on carbon dioxide (CO2) and two on carbonyl sulfide (COS) flux measurements. CO2-based methods are traditional partitioning, and a new method uses machine learning. We introduce a novel method for calculating GPP from COS fluxes, with potentially better applicability than the former methods. Both COS-based methods gave on average higher GPP estimates than the CO2-based estimates.
Lutz Beckebanze, Benjamin R. K. Runkle, Josefine Walz, Christian Wille, David Holl, Manuel Helbig, Julia Boike, Torsten Sachs, and Lars Kutzbach
Biogeosciences, 19, 3863–3876,Short summary
In this study, we present observations of lateral and vertical carbon fluxes from a permafrost-affected study site in the Russian Arctic. From this dataset we estimate the net ecosystem carbon balance for this study site. We show that lateral carbon export has a low impact on the net ecosystem carbon balance during the complete study period (3 months). Nevertheless, our results also show that lateral carbon export can exceed vertical carbon uptake at the beginning of the growing season.
Shahar Baram, Asher Bar-Tal, Alon Gal, Shmulik P. Friedman, and David Russo
Biogeosciences, 19, 3699–3711,Short summary
Static chambers are the most common tool used to measure greenhouse gas (GHG) fluxes. We tested the impact of such chambers on nitrous oxide emissions in drip irrigation. Field measurements and 3-D simulations show that the chamber base drastically affects the water and nutrient distribution in the soil and hence the measured GHG fluxes. A nomogram is suggested to determine the optimal diameter of a cylindrical chamber that ensures minimal disturbance.
Tracy E. Rankin, Nigel T. Roulet, and Tim R. Moore
Biogeosciences, 19, 3285–3303,Short summary
Peatland respiration is made up of plant and peat sources. How to separate these sources is not well known as peat respiration is not straightforward and is more influenced by vegetation dynamics than previously thought. Results of plot level measurements from shrubs and sparse grasses in a woody bog show that plants' respiration response to changes in climate is related to their different root structures, implying a difference in the mechanisms by which they obtain water resources.
Alison Bressler and Jennifer Blesh
Biogeosciences, 19, 3169–3184,Short summary
Our field experiment tested if a mixture of a nitrogen-fixing legume and non-legume cover crop could reduce nitrous oxide (N2O) emissions following tillage, compared to the legume grown alone. We found higher N2O following both legume treatments, compared to those without, and lower emissions from the cover crop mixture at one of the two test sites, suggesting that interactions between cover crop types and soil quality influence N2O emissions.
Sari Juutinen, Mika Aurela, Juha-Pekka Tuovinen, Viktor Ivakhov, Maiju Linkosalmi, Aleksi Räsänen, Tarmo Virtanen, Juha Mikola, Johanna Nyman, Emmi Vähä, Marina Loskutova, Alexander Makshtas, and Tuomas Laurila
Biogeosciences, 19, 3151–3167,Short summary
We measured CO2 and CH4 fluxes in heterogenous Arctic tundra in eastern Siberia. We found that tundra wetlands with sedge and grass vegetation contributed disproportionately to the landscape's ecosystem CO2 uptake and CH4 emissions to the atmosphere. Moreover, we observed high CH4 consumption in dry tundra, particularly in barren areas, offsetting part of the CH4 emissions from the wetlands.
Jessica Plein, Rulon W. Clark, Kyle A. Arndt, Walter C. Oechel, Douglas Stow, and Donatella Zona
Biogeosciences, 19, 2779–2794,Short summary
Tundra vegetation and the carbon balance of Arctic ecosystems can be substantially impacted by herbivory. We tested how herbivory by brown lemmings in individual enclosure plots have impacted carbon exchange of tundra ecosystems via altering carbon dioxide (CO2) and methane (CH4) fluxes. Lemmings significantly decreased net CO2 uptake while not affecting CH4 emissions. There was no significant difference in the subsequent growing season due to recovery of the vegetation.
Jenie Gil, Maija E. Marushchak, Tobias Rütting, Elizabeth M. Baggs, Tibisay Pérez, Alexander Novakovskiy, Tatiana Trubnikova, Dmitry Kaverin, Pertti J. Martikainen, and Christina Biasi
Biogeosciences, 19, 2683–2698,Short summary
N2O emissions from permafrost soils represent up to 11.6 % of total N2O emissions from natural soils, and their contribution to the global N2O budget will likely increase due to climate change. A better understanding of N2O production from permafrost soil is needed to evaluate the role of arctic ecosystems in the global N2O budget. By studying microbial N2O production processes in N2O hotspots in permafrost peatlands, we identified denitrification as the dominant source of N2O in these surfaces.
Christian Rödenbeck, Tim DeVries, Judith Hauck, Corinne Le Quéré, and Ralph F. Keeling
Biogeosciences, 19, 2627–2652,Short summary
The ocean is an important part of the global carbon cycle, taking up about a quarter of the anthropogenic CO2 emitted by burning of fossil fuels and thus slowing down climate change. However, the CO2 uptake by the ocean is, in turn, affected by variability and trends in climate. Here we use carbon measurements in the surface ocean to quantify the response of the oceanic CO2 exchange to environmental conditions and discuss possible mechanisms underlying this response.
Shuang Ma, Lifen Jiang, Rachel M. Wilson, Jeff P. Chanton, Scott Bridgham, Shuli Niu, Colleen M. Iversen, Avni Malhotra, Jiang Jiang, Xingjie Lu, Yuanyuan Huang, Jason Keller, Xiaofeng Xu, Daniel M. Ricciuto, Paul J. Hanson, and Yiqi Luo
Biogeosciences, 19, 2245–2262,Short summary
The relative ratio of wetland methane (CH4) emission pathways determines how much CH4 is oxidized before leaving the soil. We found an ebullition modeling approach that has a better performance in deep layer pore water CH4 concentration. We suggest using this approach in land surface models to accurately represent CH4 emission dynamics and response to climate change. Our results also highlight that both CH4 flux and belowground concentration data are important to constrain model parameters.
Mika Korkiakoski, Tiia Määttä, Krista Peltoniemi, Timo Penttilä, and Annalea Lohila
Biogeosciences, 19, 2025–2041,Short summary
We measured CH4 fluxes and production and oxidation potentials from irrigated and non-irrigated podzolic soil in a boreal forest. CH4 sink was smaller at the irrigated site but did not cause CH4 emission, with one exception. We also showed that under laboratory conditions, not only wet conditions, but also fresh carbon, are needed to make podzolic soil into a CH4 source. Our study provides important data for improving the process models describing the upland soil CH4 dynamics.
Sarah Shakil, Suzanne E. Tank, Jorien E. Vonk, and Scott Zolkos
Biogeosciences, 19, 1871–1890,Short summary
Permafrost thaw-driven landslides in the western Arctic are increasing organic carbon delivered to headwaters of drainage networks in the western Canadian Arctic by orders of magnitude. Through a series of laboratory experiments, we show that less than 10 % of this organic carbon is likely to be mineralized to greenhouse gases during transport in these networks. Rather most of the organic carbon is likely destined for burial and sequestration for centuries to millennia.
Wolfgang Fischer, Christoph K. Thomas, Nikita Zimov, and Mathias Göckede
Biogeosciences, 19, 1611–1633,Short summary
Arctic permafrost ecosystems may release large amounts of carbon under warmer future climates and may therefore accelerate global climate change. Our study investigated how long-term grazing by large animals influenced ecosystem characteristics and carbon budgets at a Siberian permafrost site. Our results demonstrate that such management can contribute to stabilizing ecosystems to keep carbon in the ground, particularly through drying soils and reducing methane emissions.
Dong-Gill Kim, Ben Bond-Lamberty, Youngryel Ryu, Bumsuk Seo, and Dario Papale
Biogeosciences, 19, 1435–1450,Short summary
As carbon (C) and greenhouse gas (GHG) research has adopted appropriate technology and approach (AT&A), low-cost instruments, open-source software, and participatory research and their results were well accepted by scientific communities. In terms of cost, feasibility, and performance, the integration of low-cost and low-technology, participatory and networking-based research approaches can be AT&A for enhancing C and GHG research in developing countries.
Lutz Beckebanze, Zoé Rehder, David Holl, Christian Wille, Charlotta Mirbach, and Lars Kutzbach
Biogeosciences, 19, 1225–1244,Short summary
Arctic permafrost landscapes feature many water bodies. In contrast to the terrestrial parts of the landscape, the water bodies release carbon to the atmosphere. We compare carbon dioxide and methane fluxes from small water bodies to the surrounding tundra and find not accounting for the carbon dioxide emissions leads to an overestimation of the tundra uptake by 11 %. Consequently, changes in hydrology and water body distribution may substantially impact the overall carbon budget of the Arctic.
Brian Scott, Andrew H. Baldwin, and Stephanie A. Yarwood
Biogeosciences, 19, 1151–1164,Short summary
Carbon dioxide and methane contribute to global warming. What can we do? We can build wetlands: they store carbon dioxide and should cause global cooling. But when first built they produce excess methane. Eventually built wetlands will cause cooling, but it may take decades or even centuries. How we build wetlands matters. We show that a common practice, using organic matter, such as manure, can make a big difference whether or not the wetlands we build start global cooling within our lifetime.
Jan Knappe, Celia Somlai, and Laurence W. Gill
Biogeosciences, 19, 1067–1085,Short summary
Two domestic on-site wastewater treatment systems have been monitored for greenhouse gas (carbon dioxide, methane and nitrous oxide) emissions coming from the process units, soil and vent pipes. This has enabled the net greenhouse gas per person to be quantified for the first time, as well as the impact of pre-treatment on the effluent before being discharged to soil. These decentralised wastewater treatment systems serve approx. 20 % of the population in both Europe and the United States.
Yanan Zhao, Dennis Booge, Christa A. Marandino, Cathleen Schlundt, Astrid Bracher, Elliot L. Atlas, Jonathan Williams, and Hermann W. Bange
Biogeosciences, 19, 701–714,Short summary
We present here, for the first time, simultaneously measured dimethylsulfide (DMS) seawater concentrations and DMS atmospheric mole fractions from the Peruvian upwelling region during two cruises in December 2012 and October 2015. Our results indicate low oceanic DMS concentrations and atmospheric DMS molar fractions in surface waters and the atmosphere, respectively. In addition, the Peruvian upwelling region was identified as an insignificant source of DMS emissions during both periods.
Moussa Moustapha, Loris Deirmendjian, David Sebag, Jean-Jacques Braun, Stéphane Audry, Henriette Ateba Bessa, Thierry Adatte, Carole Causserand, Ibrahima Adamou, Benjamin Ngounou Ngatcha, and Frédéric Guérin
Biogeosciences, 19, 137–163,Short summary
We monitor the spatio-temporal variability of organic and inorganic carbon (C) species in the tropical Nyong River (Cameroon), across groundwater and increasing stream orders. We show the significant contribution of wetland as a C source for tropical rivers. Thus, ignoring the river–wetland connectivity might lead to the misrepresentation of C dynamics in tropical watersheds. Finally, total fluvial carbon losses might offset ~10 % of the net C sink estimated for the whole Nyong watershed.
Alexander J. Turner, Philipp Köhler, Troy S. Magney, Christian Frankenberg, Inez Fung, and Ronald C. Cohen
Biogeosciences, 18, 6579–6588,Short summary
This work builds a high-resolution estimate (500 m) of gross primary productivity (GPP) over the US using satellite measurements of solar-induced chlorophyll fluorescence (SIF) from the TROPOspheric Monitoring Instrument (TROPOMI) between 2018 and 2020. We identify ecosystem-specific scaling factors for estimating gross primary productivity (GPP) from TROPOMI SIF. Extreme precipitation events drive four regional GPP anomalies that account for 28 % of year-to-year GPP differences across the US.
Paul Laris, Moussa Koné, Fadiala Dembélé, Christine M. Rodrigue, Lilian Yang, Rebecca Jacobs, and Quincy Laris
Biogeosciences, 18, 6229–6244,Short summary
Savanna fires play a key role in the global carbon cycle because they release methane. Although it burns the most, there are few studies from West Africa. We conducted 36 experimental fires according to local practice to collect smoke samples. We found that fires set early in the season had higher methane emissions than those set later, and head fires had double the emissions of backfires. We conclude policies to reduce emissions will not have the desired effects if fire type is not considered.
Johan H. Scheller, Mikhail Mastepanov, Hanne H. Christiansen, and Torben R. Christensen
Biogeosciences, 18, 6093–6114,Short summary
Our study presents a time series of methane emissions in a high-Arctic-tundra landscape over 14 summers, which shows large variations between years. The methane emissions from the valley are expected to more than double in the late 21st century. This warming increases permafrost thaw, which could increase surface erosion in the valley. Increased erosion could offset some of the rise in methane fluxes from the valley, but this would require large-scale impacts on vegetated surfaces.
Patryk Łakomiec, Jutta Holst, Thomas Friborg, Patrick Crill, Niklas Rakos, Natascha Kljun, Per-Ola Olsson, Lars Eklundh, Andreas Persson, and Janne Rinne
Biogeosciences, 18, 5811–5830,Short summary
Methane emission from the subarctic mire with heterogeneous permafrost status was measured for the years 2014–2016. Lower methane emission was measured from the palsa mire sector while the thawing wet sector emitted more. Both sectors have a similar annual pattern with a gentle rise during spring and a decrease during autumn. The highest emission was observed in the late summer. Winter emissions were positive during the measurement period and have a significant impact on the annual budgets.
Balázs Grosz, Reinhard Well, Rene Dechow, Jan Reent Köster, Mohammad Ibrahim Khalil, Simone Merl, Andreas Rode, Bianca Ziehmer, Amanda Matson, and Hongxing He
Biogeosciences, 18, 5681–5697,Short summary
To assure quality predictions biogeochemical models must be current. We use data measured using novel incubation methods to test the denitrification sub-modules of three models. We aim to identify limitations in the denitrification modeling to inform next steps for development. Several areas are identified, most urgently improved denitrification control parameters and further testing with high-temporal-resolution datasets. Addressing these would significantly improve denitrification modeling.
Sarah Waldo, Jake J. Beaulieu, William Barnett, D. Adam Balz, Michael J. Vanni, Tanner Williamson, and John T. Walker
Biogeosciences, 18, 5291–5311,Short summary
Human-made reservoirs impact the carbon cycle. In particular, the breakdown of organic matter in reservoir sediments can result in large emissions of greenhouse gases (especially methane) to the atmosphere. This study takes an intensive look at the patterns in greenhouse gas emissions from a single reservoir in Ohio (United States) and the role of water temperature, precipitation, and algal blooms in emissions. We saw a "spring burst" of elevated emissions that challenged our assumptions.
Xinyu Liu, Xixi Lu, Ruihong Yu, Heyang Sun, Hao Xue, Zhen Qi, Zhengxu Cao, Zhuangzhuang Zhang, and Tingxi Liu
Biogeosciences, 18, 4855–4872,Short summary
Gradual riparian wetland drying is increasingly sensitive to global warming and contributes to climate change. We analyzed the emissions of CO2, CH4, and N2O from riparian wetlands in the Xilin River basin to understand the role of these ecosystems in greenhouse gas emissions. Our study showed that anthropogenic activities have extensively changed the hydrological characteristics of the riparian wetlands and might accelerate carbon loss, which could further affect greenhouse gas emissions.
Zhaohui Chen, Parvadha Suntharalingam, Andrew J. Watson, Ute Schuster, Jiang Zhu, and Ning Zeng
Biogeosciences, 18, 4549–4570,Short summary
As the global temperature continues to increase, carbon dioxide (CO2) is a major driver of this global warming. The increased CO2 is mainly caused by emissions from fossil fuel use and land use. At the same time, the ocean is a significant sink in the carbon cycle. The North Atlantic is a critical ocean region in reducing CO2 concentration. We estimate the CO2 uptake in this region based on a carbon inverse system and atmospheric CO2 observations.
Sirwan Yamulki, Jack Forster, Georgios Xenakis, Adam Ash, Jacqui Brunt, Mike Perks, and James I. L. Morison
Biogeosciences, 18, 4227–4241,Short summary
The effect of clear-felling on soil greenhouse gas (GHG) fluxes was assessed in a Sitka spruce forest. Measurements over 4 years showed that CO2, CH4, and N2O fluxes responded differently to clear-felling due to significant changes in soil biotic and abiotic factors and showed large variations between years. Over 3 years since felling, the soil GHG flux was reduced by 45% due to a much larger reduction in CO2 efflux than increases in N2O (up to 20%) and CH4 (changed from sink to source) fluxes.
Stefan Theodorus Johannes Weideveld, Weier Liu, Merit van den Berg, Leon Peter Maria Lamers, and Christian Fritz
Biogeosciences, 18, 3881–3902,Short summary
Raising the groundwater table (GWT) trough subsoil irrigation does not lead to a reduction of carbon emissions from drained peat meadows, even though there was a clear increase in the GWT during summer. Most likely, the largest part of the peat oxidation takes place in the top 70 cm of the soil, which stays above the GWT with the use of subsoil irrigation. We conclude that the use of subsoil irrigation is ineffective as a mitigation measure to sufficiently lower peat oxidation rates.
Yanming Gong, Ping Yue, Kaihui Li, Anwar Mohammat, and Yanyan Liu
Biogeosciences, 18, 3529–3537,Short summary
At present, data on the influence of asymmetric warming on the GHG flux on a temporal scale are scarce. GHG fluxes were measured using static chambers and a gas chromatograph. Our study showed that the effect of seasonally asymmetrical warming on CO2 flux was obvious, with the GHG flux being able to adapt to continuous warming. Warming in the non-growing season increased the temperature dependence of GHG flux.
Hella van Asperen, João Rafael Alves-Oliveira, Thorsten Warneke, Bruce Forsberg, Alessandro Carioca de Araújo, and Justus Notholt
Biogeosciences, 18, 2609–2625,Short summary
Termites are insects that are highly abundant in tropical ecosystems. It is known that termites emit CH4, an important greenhouse gas, but their absolute emission remains uncertain. In the Amazon rainforest, we measured CH4 emissions from termite nests and groups of termites. In addition, we tested a fast and non-destructive field method to estimate termite nest colony size. We found that termites play a significant role in an ecosystem's CH4 budget and probably emit more than currently assumed.
Genevieve L. Noyce and J. Patrick Megonigal
Biogeosciences, 18, 2449–2463,Short summary
Methane (CH4) is a potent greenhouse gas that contributes to global radiative forcing. A mechanistic understanding of how wetland CH4 cycling will respond to global warming is crucial for improving prognostic models. We present results from the first 4 years of a novel whole-ecosystem warming experiment in a coastal wetland, showing that warming increases CH4 emissions and identifying four potential mechanisms that can be added to future modeling efforts.
Yanan Zhao, Cathleen Schlundt, Dennis Booge, and Hermann W. Bange
Biogeosciences, 18, 2161–2179,Short summary
We present a unique and comprehensive time-series study of biogenic sulfur compounds in the southwestern Baltic Sea, from 2009 to 2018. Dimethyl sulfide is one of the key players regulating global climate change, as well as dimethylsulfoniopropionate and dimethyl sulfoxide. Their decadal trends did not follow increasing temperature but followed some algae group abundances at the Boknis Eck Time Series Station.
Ingeborg Bussmann, Irina Fedorova, Bennet Juhls, Pier Paul Overduin, and Matthias Winkel
Biogeosciences, 18, 2047–2061,Short summary
Arctic rivers, lakes, and bays are affected by a warming climate. We measured the amount and consumption of methane in waters from Siberia under ice cover and in open water. In the lake, methane concentrations under ice cover were much higher than in summer, and methane consumption was highest. The ice cover leads to higher methane concentration under ice. In a warmer Arctic, there will be more time with open water when methane is consumed by bacteria, and less methane will escape into the air.
Elisa Vainio, Olli Peltola, Ville Kasurinen, Antti-Jussi Kieloaho, Eeva-Stiina Tuittila, and Mari Pihlatie
Biogeosciences, 18, 2003–2025,Short summary
We studied forest floor methane exchange over an area of 10 ha in a boreal pine forest. The results demonstrate high spatial variability in soil moisture and consequently in the methane flux. We detected wet patches emitting high amounts of methane in the early summer; however, these patches turned to methane uptake in the autumn. We concluded that the small-scale spatial variability of the boreal forest methane flux highlights the importance of soil chamber placement in similar studies.
Matthias Koschorreck, Yves T. Prairie, Jihyeon Kim, and Rafael Marcé
Biogeosciences, 18, 1619–1627,Short summary
The concentration of carbon dioxide (CO2) in water samples is often measured using a gas chromatograph. Depending on the chemical composition of the water, this method can produce wrong results. We quantified the possible error and how it depends on water composition and the analytical procedure. We propose a method to correct wrong results by additionally analysing alkalinity in the samples. We provide an easily usable computer code to perform the correction calculations.
Julia Drewer, Melissa M. Leduning, Robert I. Griffiths, Tim Goodall, Peter E. Levy, Nicholas Cowan, Edward Comynn-Platt, Garry Hayman, Justin Sentian, Noreen Majalap, and Ute M. Skiba
Biogeosciences, 18, 1559–1575,Short summary
In Southeast Asia, oil palm plantations have largely replaced tropical forests. The impact of this shift in land use on greenhouse gas fluxes and soil microbial communities remains uncertain. We have found emission rates of the potent greenhouse gas nitrous oxide on mineral soil to be higher from oil palm plantations than logged forest over a 2-year study and concluded that emissions have increased over the last 42 years in Sabah, with the proportion of emissions from plantations increasing.
Lutz Merbold, Charlotte Decock, Werner Eugster, Kathrin Fuchs, Benjamin Wolf, Nina Buchmann, and Lukas Hörtnagl
Biogeosciences, 18, 1481–1498,Short summary
Our study investigated the exchange of the three major greenhouse gases (GHGs) over a temperate grassland prior to and after restoration through tillage in central Switzerland. Our results show that irregular management events, such as tillage, have considerable effects on GHG emissions in the year of tillage while leading to enhanced carbon uptake and similar nitrogen losses via nitrous oxide in the years following tillage to those observed prior to tillage.
Roland Vernooij, Marcos Giongo, Marco Assis Borges, Máximo Menezes Costa, Ana Carolina Sena Barradas, and Guido R. van der Werf
Biogeosciences, 18, 1375–1393,Short summary
We used drones to measure greenhouse gas emission factors from fires in the Brazilian Cerrado. We compared early-dry-season management fires and late-dry-season fires to determine if fire management can be a tool for abating emissions. Although we found some evidence of increased CO and CH4 emission factors, the seasonal effect was smaller than that found in previous studies. For N2O, the third most important greenhouse gas, we found opposite trends in grass- and shrub-dominated areas.
Filippo Vingiani, Nicola Durighetto, Marcus Klaus, Jakob Schelker, Thierry Labasque, and Gianluca Botter
Biogeosciences, 18, 1223–1240,Short summary
Flexible foil chamber design and the anchored deployment might be useful techniques to enhance the robustness and the accuracy of CO2 measurements in low-order streams. Moreover, the study demonstrates the value of analytical and numerical techniques for the estimation of gas exchange velocities. These results may contribute to the development of novel procedures for chamber data analysis which might improve the robustness and reliability of chamber-based CO2 measurements in first-order streams.
Alvarez, R. A., Zavalao-Araiza, D., Lyon, D. R., Allen, D. T., Barkley, Z. R., Brandt, A. R., Davis, K. J., Herndon, S. C., Jacob, D. J., Karion, A., Korts, E. A., Lamb, B. K., Lauvaux, T., Maasakkers, J. D., Marchese, A. J., Omara, M., Pacala, J. W., Peiachl, J., Robinson, A. J., Shepson, P. B., Sweeney, C., Townsend-Small, A., Wofsy, S. C., and Hamburg, S. P.: Assessment of methane emissions from the U.S. oil and gas supply chain, Science, 361, 186–188, https://doi.org/10.1126/science.aar7204, 2018.
Baldassare, F. J., McCaffrey, M. A., and Harper, J. A.: A geochemical context for stray gas investigations in the northern Appalachian Basin: Implications of analyses of natural gases from Neogene-through Devonian-age strata, AAPG Bull., 98, 341–372, https://doi.org/10.1306/06111312178, 2014.
Botner, E. C., Townsend-Small, A., Nash, D. B., Xu, X., Schimmelmann, A., and Miller, J. H.: Monitoring concentration and isotopic composition of methane in groundwater in the Utica Shale hydraulic fracturing region of Ohio, Environ. Monit. Assess., 190, 322–337, https://doi.org/10.1007/s10661-018-6696-1, 2018.
Burruss, R. C. and Laughrey, C. D.: Carbon and hydrogen isotopic reversals in deep basin gas: evidence for limits to the stability of hydrocarbons, Org. Geochem., 41, 1285–1296, https://doi.org/10.1016/j.orggeochem.2010.09.008, 2010.
Caulton, D. R., Shepson, P. D., Santoro, R. L., Sparks, J. P., Howarth, R. W., Ingraffea, A., Camaliza, M. O., Sweeney, C., Karion, A., Davis, K. J., Stirm, B. H., Montzka, S. A., and Miller, B.: Toward a better understanding and quantification of methane emissions from shale gas development, P. Natl. Acad. Sci. USA, 111, 6237–6242, https://doi.org/10.1073/pnas.1316546111, 2014.
EIA: Shale gas and tight oil and commercially produced in just four countries, Energy Information Administration, US Department of Energy, available at: https://www.eia.gov/todayinenergy/detail.php?id=19991 (last access: 14 September 2018), 2015.
EIA: Shale gas production drives world natural gas production growth, Energy Information Administration, US Department of Energy, available at: https://www.eia.gov/todayinenergy/detail.php?id=27512 (last access: 12 September 2018), 2016.
EIA: Table 1.2, World crude oil production 1960–2017, Monthly energy review, June 2018, Energy Information Administration, US Department of Energy, 1–244, 2018.
Golding, S. D., Boreham, C. J., and Esterle, J. S.: Stable isotope geochemistry of coal bed and shale gas and related production waters: A review, Int. J. Coal Geolog., 120, 24–40, https://doi.org/10.1016/j.coal.2013.09.001, 2013.
Hao, F. and Zou, H.: Cause of shale gas geochemical anomalies and mechanisms for gas enrichment and depletion in high-maturity shales, Mar. Petrol. Geol., 44, 1–12, https://doi.org/10.1016/j.marpetgeo.2013.03.005, 2013.
Howarth, R. W.: A bridge to nowhere: Methane emissions and the greenhouse gas footprint of natural gas, Energy Sci. Eng., 2, 47–60, https://doi.org/10.1002/ese3.35, 2014.
Howarth, R. W., Santoro, R., and Ingraffea, A.: Methane and the greenhouse gas footprint of natural gas from shale formations, Clim. Change Lett., 106, 679–690, https://doi.org/10.1007/s10584-011-0061-5, 2011.
IEA: World Energy Outlook, International Energy Agency, available at: https://webstore.iea.org/world-energy-outlook-2008 (last access: 12 September 2018), 2008.
IEA: Key World Energy Statistics, International Energy Agency, available at: https://www.iea.org/publications/freepublications/publication/KeyWorld2017.pdf (last access: 12 September 2018), 2017.
IPCC: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Intergovernmental Panel on Climate Change, chap. 8, 659–740, 2013.
IPCC: Summary for Policymakers, in: Global warming of 1.5 ∘C. An IPCC Special Report on the impacts of global warming of 1.5 ∘C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty, Intergovernmental Panel on Climate Change, available at: http://www.ipcc.ch/report/sr15/ (last access: 29 March 2019), 2018.
Jacobson, M. Z., Howarth, R. W., Delucchi, M. A., Scobies, S. R., Barth, J. M., Dvorak, M. J., Klevze, M., Katkhuda, H., Miranda, B., Chowdhury, N. A., Jones, R., Plano, L., and Ingraffea, A. R.: Examining the feasibility of converting New York State's all-purpose energy infrastructure to one using wind, water, and sunlight, Energ. Policy, 57, 585–601, https://doi.org/10.1016/j.enpol.2013.02.036, 2013.
Karion, A., Sweeney, C., Pétron, G., Frost, G., Hardesty, R. M., Kofler, J., Miller, B. R., Newberger, T., Wolter, S., Banta, R., and Brewer, A.: Methane emissions estimate from airborne measurements over a western United States natural gas field, Geophys. Res. Lett., 40, 4393–4397, https://doi.org/10.1002/grl.50811, 2013.
Lamb, B. K., Cambaliza, M. O. L., Davis, K. J., Edburg, S. L., Ferrara, T. W., Floerchinger, C., Heimburger, A. M. F., Herndon, S., Lauvaux, T., Lavoie, T., Lyon, D. R., Miles, N., Prasad, K. R., Richardson, S., Roscioli, J. R., Salmon, O. E. Shepson, P. B., Stirm, B. H., and Whetstone, J.: Direct and indirect measurements and modeling of methane emissions in Indianapolis, Indiana, Environ. Sci. Technol., 50, 8910–8917, https://doi.org/10.1021/acs.est.6b01198, 2016.
Martini, A. M., Walter, L. M., Budai, J. M., Ku, T. C. W., Kaiser, C. J., and Schoell, M.: Genetic and temporal relations between formation waters and biogenic methane: Upper Devonian Antrim Shale, Michigan Basin, USA, Geochim. Cosmochim. Ac., 62, 1699–1720, 1998.
McIntosh, J. C., Walter, L. M., and Martini, A. M.: Pleistocene recharge to mid-continent basins: effects on salinity structure and microbial gas generation, Geochim. Cosmochim. Ac., 66, 1681–1700, https://doi.org/10.1016/S0016-7037(01)00885-7, 2002.
McKain, K., Down, A., Raciti, S. M., Budney, J., Hutyra, L. R., Floerchinger, C., Herndon, S. C., Nehrkorn, T., Zahniser, M. S., Jackson, R. B., Phillips, N., and Wofsy, S. C.: Methane emissions from natural gas infrastructure and use in the urban region of Boston, Massachusetts, P. Natl. Acad. Sci. USA, 112, 1941–1946, https://doi.org/10.1073/pnas.1416261112, 2015.
Miller, S. M., Michalak, A. M., Detmers, R. R., Hasekamp, O. P., Bruhwiler, L. M. P., and Schwietezke, S.: China's coal mine methane regulations have not curbed growing emissions, Nat. Commun., 10, 1–8, https://doi.org/10.1038/s41558-019-0432-x, 2019.
Nisbet, E. G., Dlugokencky, E. J., Manning, M. R., Lowry, D., Fisher, R. E., France, J. L., Michel, S. E., Miller, J. B., White, J. W. C., Vaughn, B., Bousquet, P., Pyle, J. A., Warwick, N. J., Cain, M., Brownlow, R., Zazzeri, G., Lanoiselle, M., Manning, A. C. Gloor, E., Worthy, D. E. J., Brunke, E. G., Labuschagne, C., Wolff, E. W., and Ganesan, A. L.: Rising atmospheric methane: 2007–2014 growth and isotopic shift, Global Biogeochem. Cy., 30, 1356–1370, https://doi.org/10.1002/2016GB005406, 2016.
Nisbet, E. G., Manning, M. R., Dlugokencky, E. J., Fisher, R. E., Lowry, D., Michel, S. E., Myhre, C. L., Platt, S. M., Allen, G., Bousquet, P., Brownlow, R., Cain, M., France, J. L., Hermansen, O., Hossaini, R., Jones, A. E, Levin, I., Manning, A. C., Myhre, G., Pyle, J. A., Vaughn, B. H., Warwich, N. J., and White, J. W. C.: Very strong atmospheric methane growth in the 4 years 2014–2017: Implications for the Paris Agreement, Global Biogeochem. Cy., 33, 318–342, https://doi.org/10.1029/2018GB006009, 2019.
Osborn, S. G. and McIntosh, J. C.: Chemical and isotopic tracers of the contribution of microbial gas in Devonian organic-rich shales and reservoir sandstones, northern Appalachian Basin, Appl. Geochem., 25, 456–471, https://doi.org/10.1016/j.apgeochem.2010.01.001, 2010.
Pétron, G., Karion, A., Sweeney, C., Miller, B., Montzka, S. A., Frost, G.J., Trainer, M., Tans, P., Andrews, A., Kofler, J., Helming, D., Guenther, D., Dlugokencky, E., Lang, P., Newberger, T., Wolter, S., Hall, B., Novelli, P., Brewer, R., Conley, S., Hardesty, M., Banta, R., White, A., Noone, D., Wolfe, D., and Schnell, R.: A new look at methane and nonmethane hydrocarbon emissions from oil and natural gas operations in the Colorado Denver-Julesburg Basin, J. Geophys. Res.-Atmos., 119, 6836–6852, https://doi.org/10.1002/2013JD021272, 2014.
Rice, A. L., Butenhoff, C. L., Tema, D. G., Florian, H. R., Khalil, M. A. K., and Rasmussen, R. A.: Atmospheric methane isotopic record favors fossil sources flat in 1980s and 1990s with recent increase, P. Natl. Acad. Sci. USA, 13, 10791–10796, https://doi.org/10.1073/pnas.1522923113, 2016.
Rodriguez, N. D. and Philp, R. P.: Geochemical characterization of gases from the Mississippian Barnett shale, Fort Worth Basin, Texas, AAPG Bull., 94, 1641–56, https://doi.org/10.1306/04061009119, 2010.
Rooze, J., Egger, M., Tsandev, I., and Slomp, C. P.: Iron-dependent anaerobic oxidation of methane in coastal surface sediments: Potential controls and impact, Limnol. Oceanogr., 61, S267–S282, https://doi.org/10.1002/lno.10275, 2016.
Schaefer, H., Mikaloff-Fletcher, S. E., Veidt, C., Lassey, K. R., Brailsford, G. W., Bromley, T. M., Dlubokencky, E. J., Michel, S. E., Miller, J. B., Levin, I., Lowe, D. C., Martin, R. J., Vaugn, B. H., and White, J. W. C.: A 21st century shift from fossil-fuel to biogenic methane emissions indicated by 13CH4, Science, 352, 80–84, https://doi.org/10.1126/science.aad2705, 2016.
Schlegel, M. E., McIntosh, J. C., Bates, B. L., Kirk, M. F., and Martini, A. M.: Comparison of fluid geochemistry and microbiology of multiple organic-rich reservoirs in the Illinois Basin, USA: Evidence for controls on methanogenesis and microbial transport, Geochim. Cosmochim. Ac., 75, 1903–1919, https://doi.org/10.1016/j.gca.2011.01.016, 2011.
Schneising, O., Burrows, J. P., Dickerson, R. R., Buchwitz, M., Reuter, M., and Bovensmann, H.: Remote sensing of fugitive emissions from oil and gas production in North American tight geological formations, Earth's Future, 2, 548–558, https://doi.org/10.1002/2014EF000265, 2014.
Schoell, M., Lefever, J. A., and Dow, W.: Use of maturity-related changes in gas isotopes in production and exploration of Bakken shale plays, AAPG Search and Discovery Article no. 90122 ©2011, AAPG Hedberg Conference, 5–10 December 2010, Austin, Texas, available at: http://www.searchanddiscovery.com/abstracts/pdf/2011/hedberg-beijing/abstracts/ndx_schoell.pdf (last access: 27 June 2019), 2011.
Schwietzke, S., Sherwood, O. A., Bruhwiler, L. M. P., Miller, J. B., Etiiope, G., Dlugokencky, E. J., Michel, S. E., Arling, V. A., Vaughn, B. H., White, J. W. C., and Tans, P. P.: Upward revision of global fossil fuel methane emissions based on isotope database, Nature, 538, 88–91, https://doi.org/10.1038/nature19797, 2016.
Sherwood, O. A., Schwietzke, S., Arling, V. A., and Etiope, G.: Global Inventory of Gas Geochemistry Data from Fossil Fuel, Microbial and Burning Sources, version 2017, Earth Syst. Sci. Data, 9, 63–656, https://doi.org/10.5194/essd-9-639-2017, 2017.
Shindell, D.: The social cost of atmospheric release, Climatic Change, 130, 313–326, https://doi.org/10.1007/s10584-015-1343-0, 2015.
Shindell, D., Kuylenstierna, J. C., Vignati, E., van Dingenen, R., Amann, M., Klimont, Z., Anenberg, S. C., Muller, N., Janssens-Maenhout, G., Raes, R., Schwartz, J. Falvegi, G., Pozzoli, L., Kupiainent, K., Höglund-Isaksson, L., Emberson, L., Streets, D. Ramanathan, V., Kicks, K., Oanh, N. T., Milly., G., Williams, M., Demkine, V., and Fowler, D.: Simultaneously mitigating near-term climate change and improving human health and food security, Science, 335, 183–189, https://doi.org/10.1126/science.1210026, 2012.
Tilley, B. and Muehlenbachs, K.: Isotope reversals and universal stages and trends of gas maturation in sealed, self-contained petroleum systems, Chem. Geol., 339, 194–204, https://doi.org/10.1016/j.chemgeo.2012.08.002, 2013.
Tilley, B., McLellan, S., Hiebert, S., Quartero, B., Veilleux, B., and Muehlenbachs, K.: Gas isotope reversals in fractured gas reservoirs of the western Canadian Foothills: Mature shale gases in disguise, AAPG Bull., 95, 1399–1422, https://doi.org/10.1306/01031110103, 2011.
Townsend-Small, A., Marrero, J. E., Lyon, D. R., Simpson, I. J., Meinhardi, S., and Blake, D. R.: Integrating source apportionment tracers into a bottom-up inventory of methane emissions in the Barnett shale hydraulic fracturing region, Environ. Sci. Technol., 49, 8175–8182, https://doi.org/10.1021/acs.est.5b00057, 2015.
Turner, A. J., Jacob, D. J., Benmergui, J., Wofsy, S. C., Maasakker, J. D., Butz, A., Haekamp, O., and Biraud, S. C.: A large increase in US methane emissions over the past decade inferred from satellite data and surface observations, Geophys. Res. Lett., 43, 2218–2224, https://doi.org/10.1002/2016GL067987, 2016.
Turner, A. J., Frankenberg, C., Wennber, P. O., and Jacob, D. J.: Ambiguity in the causes for decadal trends in atmospheric methane and hydroxyl, P. Natl. Acad. Sci. USA, 114, 5367–5372, 2017.
Vaughn, T. L., Bella, C. S., Picering, C. K., Schwietzke, S., Heath, G. A., Pétron, G., Zimmerle, D. J., Schnell, R. C., and Nummedal, D.: Temporal variability largely explains top-down/bottom-up difference in methane emission estimates from a natural gas production region, P. Natl. Acad. Sci. USA, 115, 11712–11717, https://doi.org/10.1073/pnas.1805687115, 2018.
Whelan, J. K., Oremland, R., Tarata, M., Smith, R., Howarth, R., and Lee, C.: Evidence for sulfate reducing and methane producing microorganisms in sediments from sites 618, 619, and 622, Reports of the Deep-Sea Drilling Project, 47, 767–775, https://doi.org/10.2973/dsdp.proc.96.147.1986, 1986.
Worden, J. R., Bloom, A. A., Pandey, S., Jiang, Z., Worden, H. M., Walter, T. W., Houweling, S., and Röckmann, T.: Reduced biomass burning emissions reconcile conflicting estimates of the post-2006 atmospheric methane budget, Nat. Commun., 8, 2227, https://doi.org/10.1038/s41467-017-02246-0, 2017.
Wunch, D., Toon, G. C., Hedelius, J. K., Vizenor, N., Roehl, C. M., Saad, K. M., Blavier, J.-F. L., Blake, D. R., and Wennberg, P. O.: Quantifying the loss of processed natural gas within California's South Coast Air Basin using long-term measurements of ethane and methane, Atmos. Chem. Phys., 16, 14091–14105, https://doi.org/10.5194/acp-16-14091-2016, 2016.
Zumberge, J., Ferworn, K., and Brown, S.: Isotopic reversal (“rollover”) in shale gases produced from the Mississippian Barnett and Fayetteville formations, Mar. Petrol. Geol., 31, 43–52, https://doi.org/10.1016/j.marpetgeo.2011.06.009, 2012.
Atmospheric methane has risen rapidly since 2008 and has become more depleted in 13C, in contrast to the trend towards more 13C enrichment in the late 20th century. Many have used this isotopic evidence to infer an increased biogenic source. Here I analyze the 13C trend with the consideration that methane from shale gas is somewhat depleted in 13C compared to other fossil fuels. I conclude that shale gas may be responsible for a third of the global increase from all sources.
Atmospheric methane has risen rapidly since 2008 and has become more depleted in 13C, in...