Articles | Volume 19, issue 16
https://doi.org/10.5194/amt-19-5387-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/amt-19-5387-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
19 Aug 2026
Research article |
| 19 Aug 2026
| 19 Aug 2026
A machine learning method for estimating atmospheric trace gas concentration baselines
Atmospheric Chemistry Research Group, School of Chemistry, University of Bristol, Bristol, UK
Earth Sciences New Zealand, Private Bag 14901, Kilbirnie, Wellington, New Zealand
Elena Fillola
Atmospheric Chemistry Research Group, School of Chemistry, University of Bristol, Bristol, UK
School of Engineering Mathematics, University of Bristol, Bristol, UK
Alistair J. Manning
Hadley Centre, Met Office, Exeter, UK
Atmospheric Chemistry Research Group, School of Chemistry, University of Bristol, Bristol, UK
Jgor Arduini
Department of Pure and Applied Sciences, University of Urbino, Urbino, 61029, Italy
Paul B. Krummel
CSIRO Environment, Aspendale, VIC, Australia
Chris R. Lunder
NILU, Kjeller, Norway
Jens Mühle
Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA
Simon O'Doherty
Atmospheric Chemistry Research Group, School of Chemistry, University of Bristol, Bristol, UK
Sunyoung Park
Department of Oceanography, Kyungpook National University, Daegu, Republic of Korea
Ronald G. Prinn
Center for Sustainability Science and Strategy, Massachusetts Institute of Technology, Cambridge, MA, USA
Stefan Reimann
Laboratory for Air Pollution/Environmental Technology, Empa, Dübendorf, Switzerland
Dickon Young
Atmospheric Chemistry Research Group, School of Chemistry, University of Bristol, Bristol, UK
Atmospheric Chemistry Research Group, School of Chemistry, University of Bristol, Bristol, UK
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Nawid Keshtmand, Elena Fillola, Jeff Clark, Raul Santos-Rodriguez, and Matthew Rigby
EGUsphere, https://doi.org/10.5194/egusphere-2026-3361, https://doi.org/10.5194/egusphere-2026-3361, 2026
This preprint is open for discussion and under review for Geoscientific Model Development (GMD).
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Scientists track greenhouse gases by measuring them in the air and working backwards to find their sources. This requires powerful computer models that are slow and expensive to run. We built an AI model called GATESBackground that quickly estimates how much gas drifts into a region from outside its borders. Tested over South America, it matched the traditional model closely while running far faster, helping make pollution tracking from satellites quicker, cheaper, and more practical worldwide.
Clara M. Nussbaumer, Colette L. Heald, Teresa Campos, Eric A. Kort, Paul B. Krummel, Ray L. Langenfelds, Monica Madronich, Kathryn McKain, Gabrielle Pétron, Ann Stavert, and Steven C. Wofsy
EGUsphere, https://doi.org/10.5194/egusphere-2026-5476, https://doi.org/10.5194/egusphere-2026-5476, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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Changes in emissions and climate increasingly impact the remote Southern Hemisphere and we know little about the consequences for the atmospheric composition. We investigate if rapid increases in the greenhouse gas methane since 2008 have led to increases in carbon monoxide. A global model confirms this hypothesis and shows that enhanced emissions from plants and rising temperatures also contribute to the trend. Observations are inconsistent and highlight the need for more accurate measurements.
Alice E. Ramsden, Anita L. Ganesan, Matthew Rigby, Chris Rennick, Tim Arnold, Emmal Safi, Edward Chung, Dafina Kikaj, Cameron Yeo, Dave Lowry, Pete Levy, Simon O'Doherty, Kieran M. Stanley, Dickon Young, Joe Pitt, Damien Martin, Morgan Lopez, Michel Ramonet, Grant L. Forster, Arnoud Frumau, and Alistair J. Manning
Atmos. Chem. Phys., 26, 11421–11448, https://doi.org/10.5194/acp-26-11421-2026, https://doi.org/10.5194/acp-26-11421-2026, 2026
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Methane is emitted from a range of anthropogenic and natural sources, each with a characteristic isotope ratio signature. We present a method for estimating emissions from multiple sources using isotopic signatures and observations of atmospheric methane isotope ratios. We show the importance of considering isotopic signature uncertainty and demonstrate how our current understanding of these signatures may be limiting this method’s ability to reduce uncertainties in emissions estimates.
Ben Adam, Rayne Holland, Daniel Van Hoomissen, James B. Burkholder, M. Anwar H. Khan, Paul Griffiths, Jens Mühle, Dudley Shallcross, and Matt Rigby
Atmos. Chem. Phys., 26, 10979–10996, https://doi.org/10.5194/acp-26-10979-2026, https://doi.org/10.5194/acp-26-10979-2026, 2026
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Some man-made gases emitted into the atmosphere can break down to form a powerful greenhouse gas called HFC-23 (hydrofluorocarbons). In this study, we use a full three-dimensional model of the atmosphere and its chemistry to improve on previous work and determine how much HFC-23 is produced from this route. Our model estimates HFC-23 production ten times lower than previously suggested, confirming that this source is a very small contributor to the total amount of HFC-23 in the atmosphere.
Kane Stone, Candice Chen, Susan Solomon, Luke M. Western, Paul B. Krummel, Gabrielle Pétron, Jens Mühle, and Simon O'Doherty
Atmos. Chem. Phys., 26, 10241–10253, https://doi.org/10.5194/acp-26-10241-2026, https://doi.org/10.5194/acp-26-10241-2026, 2026
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There is growing interest in hydrogens impact on atmospheric chemistry and climate. Here, the seasonality of hydrogen oxidation and loss to microbial activity in soils are investigated using information from the hydrofluorocarbon, HFC-152a. A large seasonal range of the soil sink, over twice that of hydroxyl loss, is seen in the Northern latitudes peaking in the late summer, while the Southern latitudes show a much lower range. This will be useful for validating model hydrogen cycles.
Joseph R. Pitt, Dominique Rust, Anita Ganesan, Luke M. Western, Martin K. Vollmer, Jens Mühle, Tobias Bühlmann, Christina M. Harth, Stephen A. Montzka, Brad D. Hall, Isaac J. Vimont, Alistair J. Manning, Alison L. Redington, Stephan Henne, Daniela B. Melo, Saurabh Annadate, Lionel Constantin, Brendan M. Murphy, Matthew Rigby, Dickon Young, Simon O'Doherty, Angelina Wenger, Chris R. Lunder, Ove Hermansen, Thomas Wagenhäuser, Andreas Engel, Jgor Arduini, Michela Maione, Jaegeun Yun, Blagoj Mitrevski, Paul B. Krummel, Paul J. Fraser, Jooil Kim, Ray H. J. Wang, Tae Siek Rhee, Peter K. Salameh, T. Gerard Spain, Stefan Reimann, Ronald G. Prinn, Ray F. Weiss, and Kieran M. Stanley
Atmos. Chem. Phys., 26, 10167–10195, https://doi.org/10.5194/acp-26-10167-2026, https://doi.org/10.5194/acp-26-10167-2026, 2026
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1,2‑Dichloroethane (DCE) can contribute to the depletion of the stratospheric ozone layer. Whether DCE reaches the stratosphere depends on where and when it is emitted. We present the ongoing measurements of DCE from the Advanced Global Atmospheric Gases Experiment (AGAGE) and National Oceanic and Atmospheric Administration (NOAA) global monitoring networks. For the period 2017–2023, our modelled average global emissions based on these observations align with another study, while regional estimates differ. This suggests remaining uncertainty in the geographical distribution of emissions.
Julian Weng, Yufang Hao, Benjamin T. Brem, Tianqu Cui, Peeyush Khare, Lubna Dada, Kaspar R. Daellenbach, Sophie Darfeuil, Gaëlle Uzu, Jean-Luc Jaffrezo, Martin Steinbacher, Stefan Reimann, Thaleia Gkraikou, Konstantina Oikonomou, Jean Sciare, Martine Collaud Coen, Claudia Mohr, Andre S. H. Prévôt, Martin Gysel-Beer, Imad El Haddad, and Patrik Winiger
EGUsphere, https://doi.org/10.5194/egusphere-2026-3660, https://doi.org/10.5194/egusphere-2026-3660, 2026
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Long-term observations at the Jungfraujoch High Altitude Research Station show that, alongside air mass transport, sustained oxidative processing shaped by atmospheric water vapor plays a central role in driving aerosol loading and composition. Combining detailed aerosol chemical characterization with process-level insights, we provide important observational benchmarks for improving atmospheric model performance in the remote free troposphere, where uncertainties remain particularly high.
Wenche Aas, Thérèse Salameh, Robert Wegener, Heidi Hellén, Jean-Luc Jaffrezo, Pontus Roldin, Elisabeth Alonso-Blanco, Andres Alastuey, Crist Amelynck, Jgor Arduini, Benjamin Bergmans, Marie Bertrand, Agnes Borbon, Efstratios Bourtsoukidis, Laetitia Bouvier, David Butterfield, Iris Buxbaum, Darius Ceburnis, Anja Claude, Augustin Colette, Aurélie Colomb, Sophie Darfeuil, James Dernie, Maximilien Desservettaz, Elías Díaz-Ramiro, Marvin Dufresne, René Dubus, Mario Duval, Marie Dury, Anna Font, Kirsten N. Fossum, Evelyn Freney, Gotzon Gangoiti, Yao Ge, Maria Carmen Gomez, Francisco J. Gómez-Moreno, Marie Gohy, Valérie Gros, Paul Hamer, Bryan Hellack, Hartmut Herrmann, Robert Holla, Adéla Holubová, Niels R. Jensen, Tuija Jokinen, Matthew Jones, Uwe Käfer, Lukas Kesper, Dieter Klemp, Dagmar Kubistin, Angela Marinoni, Martina Mazzini, Vy Ngoc Thuy Dinh, Jurgita Ovadnevaite, Tuukka Petäjä, Miguel Portillo-Estrada, Jitka Přívozníková, Jean-Philippe Putaud, Stefan Reimann, Laura Renzi, Veronique Riffault, Stuart Ritchie, Chris Robins, Begoña Artíñano Rodríguez de Torres, Laurent Poulain, Julian Rüdiger, Agnieszka Sanocka, Estibaliz Saez de Camara Oleaga, Niels Schoon, Roger Seco, Ivan Simmons, Leïla Simon, David Simpson, Sverre Solberg, Emmanuel Tison, August Thomasson, Svetlana Tsyro, Marsailidh Twigg, Toni Tykkä, Bert Verreyken, Ågot Watne, Katie Williams, Ana Maria Yáñez-Serrano, Karen Yeung, Ilona Ylivinkka, and Karl Espen Yttri
Atmos. Chem. Phys., 26, 8717–8751, https://doi.org/10.5194/acp-26-8717-2026, https://doi.org/10.5194/acp-26-8717-2026, 2026
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A one-week intensive measurement campaign during the 2022 European heatwave included monitoring of ozone, volatile organic compounds, aerosol chemical composition, and organic tracers to investigate air pollution sources. Results showed that emissions from vegetation and human activities contributed to peaks in ozone and secondary organic aerosol particles. Differences between measurements and model simulations underline the need for better characterization of sources and formation pathways.
Piers M. Forster, Tristram Walsh, Chris Smith, William F. Lamb, Robin Lamboll, Christophe Cassou, Mathias Hauser, Zeke Hausfather, June-Yi Lee, Matthew D. Palmer, Karina von Schuckmann, Aimée B. A. Slangen, Sophie Szopa, Blair Trewin, Jeongeun Yun, Nathan P. Gillett, Stuart Jenkins, H. Damon Matthews, Krishnan Raghavan, Aurélien Ribes, Joeri Rogelj, Debbie Rosen, Xuebin Zhang, Myles Allen, Robbie M. Andrew, Chris Atkinson, Richard A. Betts, Antonio Bombelli, Samantha N. Burgess, Lijing Cheng, Helen E. Claxton, Pierre Friedlingstein, Thomas L. Frölicher, Catia M. Domingues, Thomas Gasser, Catherine H. Gregory, Rachel M. Hoesly, Daniel Huppmann, Masayoshi Ishii, Christopher Kadow, Alexia Karwat, John Kennedy, Rachel E. Killick, Mahesh V. M. Kovilakam, Paul B. Krummel, Xin Lan, Jean-François Lamarque, Aurélien Liné, Belén Martín-Míguez, Didier P. Monselesan, Colin Morice, Jens Mühle, Pino Mussak, Glen P. Peters, Anna Pirani, Julia Pongratz, Matthew Rigby, Robert Rohde, Abhishek Savita, Sonia I. Seneviratne, Steven J. Smith, Ghassan Taha, Caterina Tassone, Peter Thorne, Christopher Wells, Luke M. Western, Guido R. van der Werf, Susan E. Wijffels, Marco Zecchetto, Junting Zhong, Xiao-Ye Zhang, Valérie Masson-Delmotte, and Panmao Zhai
Earth Syst. Sci. Data, 18, 3889–3933, https://doi.org/10.5194/essd-18-3889-2026, https://doi.org/10.5194/essd-18-3889-2026, 2026
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We give our annual update of key climate indicators. Our work quantifies the human contribution to global warming and the pace of climate change. This represents a large effort by the international community akin to an Intergovernmental Panel on Climate Change (IPCC) report.
Hélène De Longueville, Daniela B. Melo, Alison L. Redington, Alice Ramsden, Alexandre Danjou, Peter Andrews, Joseph Pitt, Brendan Murphy, Lionel Constantin, Kieran M. Stanley, Simon O'Doherty, Angelina Wenger, Dickon Young, Andreas Engel, Tanja Schuck, Katharina Meixner, Thomas Wagenhaeuser, Fides Gad, Martin K. Vollmer, Stefan Reimann, Michela Maoine, Jgor Arduini, Chris Lunder, Norbert Schmidtbauer, László Haszpra, Mihály Molnár, Arnoud Frumau, Cedric Couret, Matthew Rigby, Stephan Henne, Alistair Manning, and Anita L. Ganesan
Atmos. Chem. Phys., 26, 7647–7675, https://doi.org/10.5194/acp-26-7647-2026, https://doi.org/10.5194/acp-26-7647-2026, 2026
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This study estimates emissions of hydrofluorocarbons, potent greenhouse gases, in north-western Europe using atmospheric observations and atmospheric modelling. The estimates are compared with nationally reported emissions submitted to the United Nations. Overall, our results are consistent with reported values, although differences are found for some gases and countries. The findings indicate that emissions in north-western Europe are declining, reflecting the effects of climate regulations.
Paul D. Hamer, Miha Markelj, Oscar Rojas-Munoz, Bertrand Bonan, Jean-Christophe Calvet, Virginie Marécal, Alex Guenther, Heidi Trimmel, Islen Vallejo, Sabine Eckhardt, Gabriela Sousa Santos, Katerina Sindelarova, David Simpson, Norbert Schmidbauer, Heidi Hellén, Pascal Rubli, Stefan Reimann, Anja Claude, Dagmar Kubistin, Julie Cozic, James Dernie, and Leonor Tarrasón
Earth Syst. Sci. Data, 18, 3635–3669, https://doi.org/10.5194/essd-18-3635-2026, https://doi.org/10.5194/essd-18-3635-2026, 2026
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Plants release gases like isoprene that can form ozone and affect air quality. Using models and satellite data, we mapped the emissions of isoprene from plants across Europe and found that droughts can reduce leaf growth, leading to lower emissions. This shows that to understand and predict air quality, we must also understand how drought impacts vegetation. Our findings highlight the value of linking extreme weather, plant health, and pollution in models of the Earth system as a whole.
Emmal Safi, Joe Pitt, Grant Forster, Chris Rennick, Simon O’Doherty, Dickon Young, Kanokrat Charoenpornpukdee, Nick Garrard, Dafina Kikaj, Andrew Manning, Gerard Spain, Damien Martin, Morgan Lopez, Michel Ramonet, and Kieran Stanely
EGUsphere, https://doi.org/10.5194/egusphere-2026-1802, https://doi.org/10.5194/egusphere-2026-1802, 2026
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We compared whole and synthetic-air reference materials (RMs) for investigating offsets in greenhouse gas measurements so data from different sites/networks can be trusted when combined. By sending whole and synthetic-air (RMs) to six sites and measuring under routine field conditions, we found whole-air gives the most precise results, especially for carbon dioxide and nitrous oxide. Synthetic-air worked fairly well for methane but synthetic-air RMs needs lower uncertainty before wide use.
Martin K. Vollmer, Joseph R. Pitt, Dickon Young, Stephan Henne, Blagoj Mitrevski, Jens Mühle, Anita Ganesan, Jgor Arduini, Alistair J. Manning, Thomas Wagenhäuser, Alison L. Redington, Daniela B. Melo, Brendan Murphy, Ray Gluckmann, Kieran M. Stanley, Paul B. Krummel, Chris R. Lunder, Jaegeun Yun, Dominique Rust, Angelina Wenger, Myriam Guillevic, Jooil Kim, Ray H. J. Wang, Tae Siek Rhee, Lionel Constantin, Arnoud Frumau, Christina M. Harth, Peter K. Salameh, Ove Hermansen, Matthew Rigby, Luke M. Western, Andreas Engel, Simon O'Doherty, Sunyoung Park, Michela Maione, Paul J. Fraser, Ronald G. Prinn, Ray F. Weiss, and Stefan Reimann
Atmos. Chem. Phys., 26, 6993–7012, https://doi.org/10.5194/acp-26-6993-2026, https://doi.org/10.5194/acp-26-6993-2026, 2026
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Halogenated olefins (HFOs) are newly emerging compounds in the atmosphere. They are in reach of the definition of PFAS (Per- and polyfluoroalkyl substances) and some decay to the eternal chemical trifluoroacetate (TFA). We provide atmospheric measurements of three HFOs from the large Advanced Global Atmospheric Gases Experiment (AGAGE) network and estimate emissions for Northwest Europe for the first time. We find a quasi-ubiquitous presence in the atmosphere and rapidly increasing emissions.
Elinor C. Tuffnell, Emma Leedham-Elvidge, William T. Sturges, Harald Bönisch, Karina E. Adcock, Paul J. Fraser, Paul B. Krummel, David E. Oram, Ray L. Langenfelds, Thomas Röckmann, Luke M. Western, Jens Mühle, and Johannes C. Laube
Atmos. Chem. Phys., 26, 4583–4599, https://doi.org/10.5194/acp-26-4583-2026, https://doi.org/10.5194/acp-26-4583-2026, 2026
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The greater the stratospheric lifetime of chlorofluorocarbons (CFCs), the longer they will deplete ozone. This paper investigates four longer-lived CFCs, and discovers two of them have much shorter lifetimes than previously believed. Demonstrating emissions of these compounds are higher than assumed, to account for their abundance. Unusually this paper uses stratospheric whole-air samples, rather than models or lab-based experiments, to derive policy-relevant metrics for these compounds.
Enrico Mancinelli, Saurabh Annadate, Paolo Cristofanelli, Umberto Giostra, Michela Maione, Stefan Reimann, and Jgor Arduini
Atmos. Chem. Phys., 26, 4105–4129, https://doi.org/10.5194/acp-26-4105-2026, https://doi.org/10.5194/acp-26-4105-2026, 2026
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Propane is the second most abundant non-methane hydrocarbon in the atmosphere and is mainly emitted by anthropogenic activities. Despite playing a significant role in atmospheric chemistry, propane emission sources are poorly defined. Analysis of high-frequency long-term measurements at the GAW-WMO (Global Atmosphere Watch-World Meteorological Organization) station of Monte Cimone Italy make some improvements in identifications of different contributions at the regional scale.
Elena Fillola, Raul Santos-Rodriguez, Rachel Tunnicliffe, Jeffrey N. Clark, Nawid Keshtmand, Anita Ganesan, and Matthew Rigby
Geosci. Model Dev., 19, 1893–1915, https://doi.org/10.5194/gmd-19-1893-2026, https://doi.org/10.5194/gmd-19-1893-2026, 2026
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Satellite-based greenhouse gas measurements can be used in “inverse models” to improve emissions reporting, but one of the key components, the simulations of atmospheric transport, struggle to scale to large datasets. We introduce the model GATES, an AI-driven emulator that outputs transport plumes 1000× faster than traditional models. Applied to Brazil’s methane emissions, GATES produces estimates consistent with physics-based methods, offering a scalable path for timely emissions monitoring.
Rebecca H. Ward, Luke M. Western, Rachel L. Tunnicliffe, Elena Fillola, Aki Tsuruta, Tuula Aalto, and Anita L. Ganesan
Atmos. Meas. Tech., 19, 813–837, https://doi.org/10.5194/amt-19-813-2026, https://doi.org/10.5194/amt-19-813-2026, 2026
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We studied methane emissions in Arctic Alaska using satellite observations to assess how well they can monitor this important greenhouse gas. We found that emission estimates varied depending on the satellite data product and were strongly affected by assumptions in the model. Our results highlight the need for careful interpretation of emissions from Arctic satellite data and thorough testing of models, with implications for reliable climate monitoring.
Zoé Le Bras, Pascal Rubli, Christoph Hueglin, and Stefan Reimann
Atmos. Chem. Phys., 26, 869–878, https://doi.org/10.5194/acp-26-869-2026, https://doi.org/10.5194/acp-26-869-2026, 2026
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Since 1994, harmful air pollutants called BTEX (benzene, toluene, ethylbenzene and xylene) have declined by up to 89 % in the suburban area of Zurich thanks to the introduction of various air quality directives in Switzerland and in Europe. Although their contribution to ozone formation became less abundant, they still significantly contribute to the formation of airborne particles. While this study shows clear improvements in air quality, it also highlights the need for further efforts.
Benjamin Püschel, Martin Vojta, Luise Kandler, Molly Crotwell, Andreas Engel, Paul B. Krummel, Chris R. Lunder, Jens Mühle, Simon O'Doherty, Ronald G. Prinn, Kieran M. Stanley, Isaac Vimont, Martin K. Vollmer, Thomas Wagenhäuser, Ray F. Weiss, Dickon Young, and Andreas Stohl
EGUsphere, https://doi.org/10.5194/egusphere-2025-5656, https://doi.org/10.5194/egusphere-2025-5656, 2025
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We present global and regionally resolved emissions of the two highly potent greenhouse gases CF4 and C2F6 from 2006 to 2023, based on atmospheric measurements and transport modeling. In nearly all regions studied, our results show that national reports and industry-based data underestimate emissions. While emissions in Europe and the U.S. declined, we find rising emissions in South, Southeast, and East Asia. China and India are the major contributors to global emissions in recent years.
Stephan Henne, Florian R. Storck, Henry Wöhrnschimmel, Markus Leuenberger, Martin K. Vollmer, and Stefan Reimann
Atmos. Chem. Phys., 25, 18157–18186, https://doi.org/10.5194/acp-25-18157-2025, https://doi.org/10.5194/acp-25-18157-2025, 2025
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We observed the persistent, man-made trifluoroacetate (TFA) in precipitation and surface waters. Atmospheric simulations attributed TFA to precursor gases in the atmosphere. Although recently increasing concentrations could be followed, gaps in the budget indicate limited understanding of the atmospheric degradation of widely used fluorocarbons. Without additional regulation, environmental TFA concentrations are expected to rise strongly, necessitating continued monitoring and risk assessment.
Luke M. Western, Stephen Bourguet, Molly Crotwell, Lei Hu, Paul B. Krummel, Hélène De Longueville, Alistair J. Manning, Jens Mühle, Dominique Rust, Isaac Vimont, Martin K. Vollmer, Minde An, Jgor Arduini, Andreas Engel, Paul J. Fraser, Anita L. Ganesan, Christina M. Harth, Chris Lunder, Michela Maione, Stephen A. Montzka, David Nance, Simon O'Doherty, Sunyoung Park, Stefan Reimann, Peter K. Salameh, Roland Schmidt, Kieran M. Stanley, Thomas Wagenhäuser, Dickon Young, Matt Rigby, Ronald G. Prinn, and Ray F. Weiss
Atmos. Chem. Phys., 25, 17761–17778, https://doi.org/10.5194/acp-25-17761-2025, https://doi.org/10.5194/acp-25-17761-2025, 2025
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We used atmospheric measurements to estimate emissions of two hydrochlorofluorocarbon (HCFC) gases, called HCFC-123 and HCFC-124, that harm the ozone layer. Despite international regulation to stop their production, their emissions have not fallen. This may be linked to how they are used to make other chemicals. Our findings show that some banned substances are still reaching the atmosphere, likely through leaks during chemical production, which could slow the recovery of the ozone layer.
Luke M. Western, Matthew Rigby, Jens Mühle, Paul B. Krummel, Chris R. Lunder, Simon O'Doherty, Stefan Reimann, Martin K. Vollmer, Dickon Young, Ben Adam, Paul J. Fraser, Anita L. Ganesan, Christina M. Harth, Ove Hermansen, Jooil Kim, Ray L. Langenfelds, Zoë M. Loh, Blagoj Mitrevski, Joseph R. Pitt, Peter K. Salameh, Roland Schmidt, Kieran Stanley, Ann R. Stavert, Hsiang-Jui Wang, Ray F. Weiss, and Ronald G. Prinn
Earth Syst. Sci. Data, 17, 6557–6582, https://doi.org/10.5194/essd-17-6557-2025, https://doi.org/10.5194/essd-17-6557-2025, 2025
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We used global measurements and an atmospheric model to estimate how emissions and abundances of 42 chemically and radiatively important trace gases have changed over time. These gases affect the Earth's radiative balance and the ozone layer. Our data sets help track progress in reducing emissions of these gases to the atmosphere. This work supports international efforts to protect the environment by providing clear, long-term, consistent data on how these gases are changing in the atmosphere.
Martin Vojta, Andreas Plach, Rona L. Thompson, Pallav Purohit, Kieran Stanley, Simon O'Doherty, Dickon Young, Joe Pitt, Jgor Arduini, Xin Lan, and Andreas Stohl
Atmos. Chem. Phys., 25, 15197–15243, https://doi.org/10.5194/acp-25-15197-2025, https://doi.org/10.5194/acp-25-15197-2025, 2025
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We determine European emissions of the highly potent greenhouse gas sulfur hexafluoride from 2005 to 2021 – focusing on high-emitting countries and the aggregated EU-27 emissions. Emissions declined in most regions, likely due to EU F-gas regulations. However, our results reveal that most studied countries underestimate their emissions in their national reports. Our sensitivity tests highlight the importance of dense observational networks for reliable inversion-based emission estimates.
Fabian Maier, Eva Falge, Maksym Gachkivskyi, Stephan Henne, Ute Karstens, Dafina Kikaj, Ingeborg Levin, Alistair Manning, Christian Rödenbeck, and Christoph Gerbig
Atmos. Chem. Phys., 25, 12779–12809, https://doi.org/10.5194/acp-25-12779-2025, https://doi.org/10.5194/acp-25-12779-2025, 2025
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The radioactive noble gas radon (222Rn) is a suitable natural tracer for atmospheric transport and mixing processes that can be used to validate and calibrate atmospheric transport models. However, this requires accurate estimates of the 222Rn flux from the soil into the atmosphere. In our study, we evaluate the reliability of process-based 222Rn flux maps for Europe using a 222Rn inversion. Our inversion results can give some indications on how to improve the process-based 222Rn flux maps.
Piers M. Forster, Chris Smith, Tristram Walsh, William F. Lamb, Robin Lamboll, Christophe Cassou, Mathias Hauser, Zeke Hausfather, June-Yi Lee, Matthew D. Palmer, Karina von Schuckmann, Aimée B. A. Slangen, Sophie Szopa, Blair Trewin, Jeongeun Yun, Nathan P. Gillett, Stuart Jenkins, H. Damon Matthews, Krishnan Raghavan, Aurélien Ribes, Joeri Rogelj, Debbie Rosen, Xuebin Zhang, Myles Allen, Lara Aleluia Reis, Robbie M. Andrew, Richard A. Betts, Alex Borger, Jiddu A. Broersma, Samantha N. Burgess, Lijing Cheng, Pierre Friedlingstein, Catia M. Domingues, Marco Gambarini, Thomas Gasser, Johannes Gütschow, Masayoshi Ishii, Christopher Kadow, John Kennedy, Rachel E. Killick, Paul B. Krummel, Aurélien Liné, Didier P. Monselesan, Colin Morice, Jens Mühle, Vaishali Naik, Glen P. Peters, Anna Pirani, Julia Pongratz, Jan C. Minx, Matthew Rigby, Robert Rohde, Abhishek Savita, Sonia I. Seneviratne, Peter Thorne, Christopher Wells, Luke M. Western, Guido R. van der Werf, Susan E. Wijffels, Valérie Masson-Delmotte, and Panmao Zhai
Earth Syst. Sci. Data, 17, 2641–2680, https://doi.org/10.5194/essd-17-2641-2025, https://doi.org/10.5194/essd-17-2641-2025, 2025
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In a rapidly changing climate, evidence-based decision-making benefits from up-to-date and timely information. Here we compile monitoring datasets to track real-world changes over time. To make our work relevant to policymakers, we follow methods from the Intergovernmental Panel on Climate Change (IPCC). Human activities are increasing the Earth's energy imbalance and driving faster sea-level rise compared to the IPCC assessment.
Marielle Saunois, Adrien Martinez, Benjamin Poulter, Zhen Zhang, Peter A. Raymond, Pierre Regnier, Josep G. Canadell, Robert B. Jackson, Prabir K. Patra, Philippe Bousquet, Philippe Ciais, Edward J. Dlugokencky, Xin Lan, George H. Allen, David Bastviken, David J. Beerling, Dmitry A. Belikov, Donald R. Blake, Simona Castaldi, Monica Crippa, Bridget R. Deemer, Fraser Dennison, Giuseppe Etiope, Nicola Gedney, Lena Höglund-Isaksson, Meredith A. Holgerson, Peter O. Hopcroft, Gustaf Hugelius, Akihiko Ito, Atul K. Jain, Rajesh Janardanan, Matthew S. Johnson, Thomas Kleinen, Paul B. Krummel, Ronny Lauerwald, Tingting Li, Xiangyu Liu, Kyle C. McDonald, Joe R. Melton, Jens Mühle, Jurek Müller, Fabiola Murguia-Flores, Yosuke Niwa, Sergio Noce, Shufen Pan, Robert J. Parker, Changhui Peng, Michel Ramonet, William J. Riley, Gerard Rocher-Ros, Judith A. Rosentreter, Motoki Sasakawa, Arjo Segers, Steven J. Smith, Emily H. Stanley, Joël Thanwerdas, Hanqin Tian, Aki Tsuruta, Francesco N. Tubiello, Thomas S. Weber, Guido R. van der Werf, Douglas E. J. Worthy, Yi Xi, Yukio Yoshida, Wenxin Zhang, Bo Zheng, Qing Zhu, Qiuan Zhu, and Qianlai Zhuang
Earth Syst. Sci. Data, 17, 1873–1958, https://doi.org/10.5194/essd-17-1873-2025, https://doi.org/10.5194/essd-17-1873-2025, 2025
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Methane (CH4) is the second most important human-influenced greenhouse gas in terms of climate forcing after carbon dioxide (CO2). A consortium of multi-disciplinary scientists synthesise and update the budget of the sources and sinks of CH4. This edition benefits from important progress in estimating emissions from lakes and ponds, reservoirs, and streams and rivers. For the 2010s decade, global CH4 emissions are estimated at 575 Tg CH4 yr-1, including ~65 % from anthropogenic sources.
Timur Cinay, Dickon Young, Nazaret Narváez Jimenez, Cristina Vintimilla-Palacios, Ariel Pila Alonso, Paul B. Krummel, William Vizuete, and Andrew R. Babbin
Atmos. Chem. Phys., 25, 4703–4718, https://doi.org/10.5194/acp-25-4703-2025, https://doi.org/10.5194/acp-25-4703-2025, 2025
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We present the initial 15 months of nitrous oxide measurements from the Galapagos Emissions Monitoring Station. The observed variability in atmospheric mole fractions during this period can be linked to several factors: seasonal variations in trade wind speed and direction across the eastern Pacific, differences in the transport history of air masses sampled, and spatiotemporal heterogeneity in regional marine nitrous oxide emissions from the coastal upwelling systems of Peru and Chile.
Tahereh Alinejadtabrizi, Yi Huang, Francisco Lang, Steven Siems, Michael Manton, Luis Ackermann, Melita Keywood, Ruhi Humphries, Paul Krummel, Alastair Williams, and Greg Ayers
Atmos. Chem. Phys., 25, 2631–2648, https://doi.org/10.5194/acp-25-2631-2025, https://doi.org/10.5194/acp-25-2631-2025, 2025
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Clouds over the Southern Ocean are crucial to Earth's energy balance, but understanding the factors that control them is complex. Our research examines how weather patterns affect tiny particles called cloud condensation nuclei (CCN), which influence cloud properties. Using data from Kennaook / Cape Grim, we found that winter air from Antarctica brings cleaner conditions with lower CCN, while summer patterns from Australia transport more particles. Precipitation also helps reduce CCN in winter.
Maitane Iturrate-Garcia, Thérèse Salameh, Paul Schlauri, Annarita Baldan, Martin K. Vollmer, Evdokia Stratigou, Sebastien Dusanter, Jianrong Li, Stefan Persijn, Anja Claude, Rupert Holzinger, Christophe Sutour, Tatiana Macé, Yasin Elshorbany, Andreas Ackermann, Céline Pascale, and Stefan Reimann
Atmos. Meas. Tech., 18, 371–403, https://doi.org/10.5194/amt-18-371-2025, https://doi.org/10.5194/amt-18-371-2025, 2025
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Accurate and comparable measurements of oxygenated organic compounds (OVOCs) are crucial in assessing tropospheric ozone burdens and trends. However, the monitoring of many OVOCs remains challenging because of their low atmospheric abundance and lack of stable and traceable calibration standards. This paper describes the calibration standards developed for OVOCs at a low amount of substance fractions (<100 nmol mol-1) to transfer traceability of the International System of Units to the field.
Xiansheng Liu, Xun Zhang, Marvin Dufresne, Tao Wang, Lijie Wu, Rosa Lara, Roger Seco, Marta Monge, Ana Maria Yáñez-Serrano, Marie Gohy, Paul Petit, Audrey Chevalier, Marie-Pierre Vagnot, Yann Fortier, Alexia Baudic, Véronique Ghersi, Grégory Gille, Ludovic Lanzi, Valérie Gros, Leïla Simon, Heidi Héllen, Stefan Reimann, Zoé Le Bras, Michelle Jessy Müller, David Beddows, Siqi Hou, Zongbo Shi, Roy M. Harrison, William Bloss, James Dernie, Stéphane Sauvage, Philip K. Hopke, Xiaoli Duan, Taicheng An, Alastair C. Lewis, James R. Hopkins, Eleni Liakakou, Nikolaos Mihalopoulos, Xiaohu Zhang, Andrés Alastuey, Xavier Querol, and Thérèse Salameh
Atmos. Chem. Phys., 25, 625–638, https://doi.org/10.5194/acp-25-625-2025, https://doi.org/10.5194/acp-25-625-2025, 2025
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This study examines BTEX (benzene, toluene, ethylbenzene, xylenes) pollution in urban areas across seven European countries. Analyzing data from 22 monitoring sites, we found traffic and industrial activities significantly impact BTEX levels, with peaks during rush hours. The risk from BTEX exposure remains moderate, especially in high-traffic and industrial zones, highlighting the need for targeted air quality management to protect public health and improve urban air quality.
Dafina Kikaj, Edward Chung, Alan D. Griffiths, Scott D. Chambers, Grant Forster, Angelina Wenger, Penelope Pickers, Chris Rennick, Simon O'Doherty, Joseph Pitt, Kieran Stanley, Dickon Young, Leigh S. Fleming, Karina Adcock, Emmal Safi, and Tim Arnold
Atmos. Meas. Tech., 18, 151–175, https://doi.org/10.5194/amt-18-151-2025, https://doi.org/10.5194/amt-18-151-2025, 2025
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We present a protocol to improve confidence in atmospheric radon measurements, enabling site comparisons and integration with greenhouse gas data. As a natural tracer, radon provides an independent check of transport model performance. This standardized method enhances radon’s use as a metric for model evaluation. Beyond UK observatories, it can support broader networks like ICOS and WMO/GAW, advancing global atmospheric research.
Martin Vojta, Andreas Plach, Saurabh Annadate, Sunyoung Park, Gawon Lee, Pallav Purohit, Florian Lindl, Xin Lan, Jens Mühle, Rona L. Thompson, and Andreas Stohl
Atmos. Chem. Phys., 24, 12465–12493, https://doi.org/10.5194/acp-24-12465-2024, https://doi.org/10.5194/acp-24-12465-2024, 2024
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We constrain the global emissions of the very potent greenhouse gas sulfur hexafluoride (SF6) between 2005 and 2021. We show that SF6 emissions are decreasing in the USA and in the EU, while they are substantially growing in China, leading overall to an increasing global emission trend. The national reports for the USA, EU, and China all underestimated their SF6 emissions. However, stringent mitigation measures can successfully reduce SF6 emissions, as can be seen in the EU emission trend.
Gabrielle Pétron, Andrew M. Crotwell, John Mund, Molly Crotwell, Thomas Mefford, Kirk Thoning, Bradley Hall, Duane Kitzis, Monica Madronich, Eric Moglia, Donald Neff, Sonja Wolter, Armin Jordan, Paul Krummel, Ray Langenfelds, and John Patterson
Atmos. Meas. Tech., 17, 4803–4823, https://doi.org/10.5194/amt-17-4803-2024, https://doi.org/10.5194/amt-17-4803-2024, 2024
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Hydrogen (H2) is a gas in trace amounts in the Earth’s atmosphere with indirect impacts on climate and air quality. Renewed interest in H2 as a low- or zero-carbon source of energy may lead to increased production, uses, and supply chain emissions. NOAA measurements of weekly air samples collected between 2009 and 2021 at over 50 sites in mostly remote locations are now available, and they complement other datasets to study the H2 global budget.
Yao Ge, Sverre Solberg, Mathew R. Heal, Stefan Reimann, Willem van Caspel, Bryan Hellack, Thérèse Salameh, and David Simpson
Atmos. Chem. Phys., 24, 7699–7729, https://doi.org/10.5194/acp-24-7699-2024, https://doi.org/10.5194/acp-24-7699-2024, 2024
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Atmospheric volatile organic compounds (VOCs) constitute many species, acting as precursors to ozone and aerosol. Given the uncertainties in VOC emissions, lack of evaluation studies, and recent changes in emissions, this work adapts the EMEP MSC-W to evaluate emission inventories in Europe. We focus on the varying agreement between modelled and measured VOCs across different species and underscore potential inaccuracies in total and sector-specific emission estimates.
Haklim Choi, Alison L. Redington, Hyeri Park, Jooil Kim, Rona L. Thompson, Jens Mühle, Peter K. Salameh, Christina M. Harth, Ray F. Weiss, Alistair J. Manning, and Sunyoung Park
Atmos. Chem. Phys., 24, 7309–7330, https://doi.org/10.5194/acp-24-7309-2024, https://doi.org/10.5194/acp-24-7309-2024, 2024
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We analyzed with an inversion model the atmospheric abundance of hydrofluorocarbons (HFCs), potent greenhouse gases, from 2008 to 2020 at Gosan station in South Korea and revealed a significant increase in emissions, especially from eastern China and Japan. This increase contradicts reported data, underscoring the need for accurate monitoring and reporting. Our findings are crucial for understanding and managing global HFCs emissions, highlighting the importance of efforts to reduce HFCs.
Hanqin Tian, Naiqing Pan, Rona L. Thompson, Josep G. Canadell, Parvadha Suntharalingam, Pierre Regnier, Eric A. Davidson, Michael Prather, Philippe Ciais, Marilena Muntean, Shufen Pan, Wilfried Winiwarter, Sönke Zaehle, Feng Zhou, Robert B. Jackson, Hermann W. Bange, Sarah Berthet, Zihao Bian, Daniele Bianchi, Alexander F. Bouwman, Erik T. Buitenhuis, Geoffrey Dutton, Minpeng Hu, Akihiko Ito, Atul K. Jain, Aurich Jeltsch-Thömmes, Fortunat Joos, Sian Kou-Giesbrecht, Paul B. Krummel, Xin Lan, Angela Landolfi, Ronny Lauerwald, Ya Li, Chaoqun Lu, Taylor Maavara, Manfredi Manizza, Dylan B. Millet, Jens Mühle, Prabir K. Patra, Glen P. Peters, Xiaoyu Qin, Peter Raymond, Laure Resplandy, Judith A. Rosentreter, Hao Shi, Qing Sun, Daniele Tonina, Francesco N. Tubiello, Guido R. van der Werf, Nicolas Vuichard, Junjie Wang, Kelley C. Wells, Luke M. Western, Chris Wilson, Jia Yang, Yuanzhi Yao, Yongfa You, and Qing Zhu
Earth Syst. Sci. Data, 16, 2543–2604, https://doi.org/10.5194/essd-16-2543-2024, https://doi.org/10.5194/essd-16-2543-2024, 2024
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Atmospheric concentrations of nitrous oxide (N2O), a greenhouse gas 273 times more potent than carbon dioxide, have increased by 25 % since the preindustrial period, with the highest observed growth rate in 2020 and 2021. This rapid growth rate has primarily been due to a 40 % increase in anthropogenic emissions since 1980. Observed atmospheric N2O concentrations in recent years have exceeded the worst-case climate scenario, underscoring the importance of reducing anthropogenic N2O emissions.
Piers M. Forster, Chris Smith, Tristram Walsh, William F. Lamb, Robin Lamboll, Bradley Hall, Mathias Hauser, Aurélien Ribes, Debbie Rosen, Nathan P. Gillett, Matthew D. Palmer, Joeri Rogelj, Karina von Schuckmann, Blair Trewin, Myles Allen, Robbie Andrew, Richard A. Betts, Alex Borger, Tim Boyer, Jiddu A. Broersma, Carlo Buontempo, Samantha Burgess, Chiara Cagnazzo, Lijing Cheng, Pierre Friedlingstein, Andrew Gettelman, Johannes Gütschow, Masayoshi Ishii, Stuart Jenkins, Xin Lan, Colin Morice, Jens Mühle, Christopher Kadow, John Kennedy, Rachel E. Killick, Paul B. Krummel, Jan C. Minx, Gunnar Myhre, Vaishali Naik, Glen P. Peters, Anna Pirani, Julia Pongratz, Carl-Friedrich Schleussner, Sonia I. Seneviratne, Sophie Szopa, Peter Thorne, Mahesh V. M. Kovilakam, Elisa Majamäki, Jukka-Pekka Jalkanen, Margreet van Marle, Rachel M. Hoesly, Robert Rohde, Dominik Schumacher, Guido van der Werf, Russell Vose, Kirsten Zickfeld, Xuebin Zhang, Valérie Masson-Delmotte, and Panmao Zhai
Earth Syst. Sci. Data, 16, 2625–2658, https://doi.org/10.5194/essd-16-2625-2024, https://doi.org/10.5194/essd-16-2625-2024, 2024
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This paper tracks some key indicators of global warming through time, from 1850 through to the end of 2023. It is designed to give an authoritative estimate of global warming to date and its causes. We find that in 2023, global warming reached 1.3 °C and is increasing at over 0.2 °C per decade. This is caused by all-time-high greenhouse gas emissions.
Yiming Xu, Qianlai Zhuang, Bailu Zhao, Michael Billmire, Christopher Cook, Jeremy Graham, Nancy French, and Ronald Prinn
EGUsphere, https://doi.org/10.5194/egusphere-2024-1324, https://doi.org/10.5194/egusphere-2024-1324, 2024
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We use a process-based model to simulate the fire impacts on soil thermal and hydrological dynamics and carbon budget of forest ecosystems in Northern Eurasia based on satellite-derived burn severity data. We find that fire severity generally increases in this region during the study period. Simulations indicate that fires increase soil temperature and water runoff. Fires lead the forest ecosystems to lose 2.3 Pg C, shifting the forests from a carbon sink to a source in this period.
Hannah Chawner, Eric Saboya, Karina E. Adcock, Tim Arnold, Yuri Artioli, Caroline Dylag, Grant L. Forster, Anita Ganesan, Heather Graven, Gennadi Lessin, Peter Levy, Ingrid T. Luijkx, Alistair Manning, Penelope A. Pickers, Chris Rennick, Christian Rödenbeck, and Matthew Rigby
Atmos. Chem. Phys., 24, 4231–4252, https://doi.org/10.5194/acp-24-4231-2024, https://doi.org/10.5194/acp-24-4231-2024, 2024
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The quantity of atmospheric potential oxygen (APO), derived from coincident measurements of carbon dioxide (CO2) and oxygen (O2), has been proposed as a tracer for fossil fuel CO2 emissions. In this model sensitivity study, we examine the use of APO for this purpose in the UK and compare our model to observations. We find that our model simulations are most sensitive to uncertainties relating to ocean fluxes and boundary conditions.
Emily Dowd, Alistair J. Manning, Bryn Orth-Lashley, Marianne Girard, James France, Rebecca E. Fisher, Dave Lowry, Mathias Lanoisellé, Joseph R. Pitt, Kieran M. Stanley, Simon O'Doherty, Dickon Young, Glen Thistlethwaite, Martyn P. Chipperfield, Emanuel Gloor, and Chris Wilson
Atmos. Meas. Tech., 17, 1599–1615, https://doi.org/10.5194/amt-17-1599-2024, https://doi.org/10.5194/amt-17-1599-2024, 2024
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We provide the first validation of the satellite-derived emission estimates using surface-based mobile greenhouse gas surveys of an active gas leak detected near Cheltenham, UK. GHGSat’s emission estimates broadly agree with the surface-based mobile survey and steps were taken to fix the leak, highlighting the importance of satellite data in identifying emissions and helping to reduce our human impact on climate change.
Rona L. Thompson, Stephen A. Montzka, Martin K. Vollmer, Jgor Arduini, Molly Crotwell, Paul B. Krummel, Chris Lunder, Jens Mühle, Simon O'Doherty, Ronald G. Prinn, Stefan Reimann, Isaac Vimont, Hsiang Wang, Ray F. Weiss, and Dickon Young
Atmos. Chem. Phys., 24, 1415–1427, https://doi.org/10.5194/acp-24-1415-2024, https://doi.org/10.5194/acp-24-1415-2024, 2024
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The hydroxyl radical determines the atmospheric lifetimes of numerous species including methane. Since OH is very short-lived, it is not possible to directly measure its concentration on scales relevant for understanding its effect on other species. Here, OH is inferred by looking at changes in hydrofluorocarbons (HFCs). We find that OH levels have been fairly stable over our study period (2004 to 2021), suggesting that OH is not the main driver of the recent increase in atmospheric methane.
Tanja J. Schuck, Johannes Degen, Eric Hintsa, Peter Hoor, Markus Jesswein, Timo Keber, Daniel Kunkel, Fred Moore, Florian Obersteiner, Matt Rigby, Thomas Wagenhäuser, Luke M. Western, Andreas Zahn, and Andreas Engel
Atmos. Chem. Phys., 24, 689–705, https://doi.org/10.5194/acp-24-689-2024, https://doi.org/10.5194/acp-24-689-2024, 2024
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We study the interhemispheric gradient of sulfur hexafluoride (SF6), a strong long-lived greenhouse gas. Its emissions are stronger in the Northern Hemisphere; therefore, mixing ratios in the Southern Hemisphere lag behind. Comparing the observations to a box model, the model predicts air in the Southern Hemisphere to be older. For a better agreement, the emissions used as model input need to be increased (and their spatial pattern changed), and we need to modify north–south transport.
Douglas E. J. Worthy, Michele K. Rauh, Lin Huang, Felix R. Vogel, Alina Chivulescu, Kenneth A. Masarie, Ray L. Langenfelds, Paul B. Krummel, Colin E. Allison, Andrew M. Crotwell, Monica Madronich, Gabrielle Pétron, Ingeborg Levin, Samuel Hammer, Sylvia Michel, Michel Ramonet, Martina Schmidt, Armin Jordan, Heiko Moossen, Michael Rothe, Ralph Keeling, and Eric J. Morgan
Atmos. Meas. Tech., 16, 5909–5935, https://doi.org/10.5194/amt-16-5909-2023, https://doi.org/10.5194/amt-16-5909-2023, 2023
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Network compatibility is important for inferring greenhouse gas fluxes at global or regional scales. This study is the first assessment of the measurement agreement among seven individual programs within the World Meteorological Organization community. It compares co-located flask air measurements at the Alert Observatory in Canada over a 17-year period. The results provide stronger confidence in the uncertainty estimation while using those datasets in various data interpretation applications.
John D. Patterson, Murat Aydin, Andrew M. Crotwell, Gabrielle Pétron, Jeffery P. Severinghaus, Paul B. Krummel, Ray L. Langenfelds, Vasilii V. Petrenko, and Eric S. Saltzman
Clim. Past, 19, 2535–2550, https://doi.org/10.5194/cp-19-2535-2023, https://doi.org/10.5194/cp-19-2535-2023, 2023
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Atmospheric levels of molecular hydrogen (H2) can impact climate and air quality. Constraining past changes to atmospheric H2 is useful for understanding how H2 cycles through the Earth system and predicting the impacts of increasing anthropogenic emissions under the
hydrogen economy. Here, we use the aging air found in the polar snowpack to reconstruct H2 levels over the past 100 years. We find that H2 levels increased by 30 % over Greenland and 60 % over Antarctica during the 20th century.
Ioannis Katharopoulos, Dominique Rust, Martin K. Vollmer, Dominik Brunner, Stefan Reimann, Simon J. O'Doherty, Dickon Young, Kieran M. Stanley, Tanja Schuck, Jgor Arduini, Lukas Emmenegger, and Stephan Henne
Atmos. Chem. Phys., 23, 14159–14186, https://doi.org/10.5194/acp-23-14159-2023, https://doi.org/10.5194/acp-23-14159-2023, 2023
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The effectiveness of climate change mitigation needs to be scrutinized by monitoring greenhouse gas (GHG) emissions. Countries report their emissions to the UN in a bottom-up manner. By combining atmospheric observations and transport models someone can independently validate emission estimates in a top-down fashion. We report Swiss emissions of synthetic GHGs based on kilometer-scale transport and inverse modeling, highlighting the role of appropriate resolution in complex terrain.
Hyeri Park, Jooil Kim, Haklim Choi, Sohyeon Geum, Yeaseul Kim, Rona L. Thompson, Jens Mühle, Peter K. Salameh, Christina M. Harth, Kieran M. Stanley, Simon O'Doherty, Paul J. Fraser, Peter G. Simmonds, Paul B. Krummel, Ray F. Weiss, Ronald G. Prinn, and Sunyoung Park
Atmos. Chem. Phys., 23, 9401–9411, https://doi.org/10.5194/acp-23-9401-2023, https://doi.org/10.5194/acp-23-9401-2023, 2023
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Based on atmospheric HFC-23 observations, the first estimate of post-CDM HFC-23 emissions in eastern Asia for 2008–2019 shows that these emissions contribute significantly to the global emissions rise. The observation-derived emissions were much larger than the bottom-up estimates expected to approach zero after 2015 due to national abatement activities. These discrepancies could be attributed to unsuccessful factory-level HFC-23 abatement and inaccurate quantification of emission reductions.
Emily Dowd, Chris Wilson, Martyn P. Chipperfield, Emanuel Gloor, Alistair Manning, and Ruth Doherty
Atmos. Chem. Phys., 23, 7363–7382, https://doi.org/10.5194/acp-23-7363-2023, https://doi.org/10.5194/acp-23-7363-2023, 2023
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Surface observations of methane show that the seasonal cycle amplitude (SCA) of methane is decreasing in the northern high latitudes (NHLs) but increased globally (1995–2020). The NHL decrease is counterintuitive, as we expect the SCA to increase with increasing concentrations. We use a chemical transport model to investigate changes in SCA in the NHLs. We find well-mixed methane and changes in emissions from Canada, the Middle East, and Europe are the largest contributors to the SCA in NHLs.
Alison L. Redington, Alistair J. Manning, Stephan Henne, Francesco Graziosi, Luke M. Western, Jgor Arduini, Anita L. Ganesan, Christina M. Harth, Michela Maione, Jens Mühle, Simon O'Doherty, Joseph Pitt, Stefan Reimann, Matthew Rigby, Peter K. Salameh, Peter G. Simmonds, T. Gerard Spain, Kieran Stanley, Martin K. Vollmer, Ray F. Weiss, and Dickon Young
Atmos. Chem. Phys., 23, 7383–7398, https://doi.org/10.5194/acp-23-7383-2023, https://doi.org/10.5194/acp-23-7383-2023, 2023
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Chlorofluorocarbons (CFCs) were used in Europe pre-1990, damaging the stratospheric ozone layer. Legislation has controlled production and use, and global emissions have decreased sharply. The global rate of decline in CFC-11 recently slowed and was partly attributed to illegal emission in eastern China. This study concludes that emissions of CFC-11 in western Europe have not contributed to the unexplained part of the global increase in CFC-11 observed in the last decade.
Elena Fillola, Raul Santos-Rodriguez, Alistair Manning, Simon O'Doherty, and Matt Rigby
Geosci. Model Dev., 16, 1997–2009, https://doi.org/10.5194/gmd-16-1997-2023, https://doi.org/10.5194/gmd-16-1997-2023, 2023
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Lagrangian particle dispersion models are used extensively for the estimation of greenhouse gas (GHG) fluxes using atmospheric observations. However, these models do not scale well as data volumes increase. Here, we develop a proof-of-concept machine learning emulator that can produce outputs similar to those of the dispersion model, but 50 000 times faster, using only meteorological inputs. This works demonstrates the potential of machine learning to accelerate GHG estimations across the globe.
Ana Maria Roxana Petrescu, Chunjing Qiu, Matthew J. McGrath, Philippe Peylin, Glen P. Peters, Philippe Ciais, Rona L. Thompson, Aki Tsuruta, Dominik Brunner, Matthias Kuhnert, Bradley Matthews, Paul I. Palmer, Oksana Tarasova, Pierre Regnier, Ronny Lauerwald, David Bastviken, Lena Höglund-Isaksson, Wilfried Winiwarter, Giuseppe Etiope, Tuula Aalto, Gianpaolo Balsamo, Vladislav Bastrikov, Antoine Berchet, Patrick Brockmann, Giancarlo Ciotoli, Giulia Conchedda, Monica Crippa, Frank Dentener, Christine D. Groot Zwaaftink, Diego Guizzardi, Dirk Günther, Jean-Matthieu Haussaire, Sander Houweling, Greet Janssens-Maenhout, Massaer Kouyate, Adrian Leip, Antti Leppänen, Emanuele Lugato, Manon Maisonnier, Alistair J. Manning, Tiina Markkanen, Joe McNorton, Marilena Muntean, Gabriel D. Oreggioni, Prabir K. Patra, Lucia Perugini, Isabelle Pison, Maarit T. Raivonen, Marielle Saunois, Arjo J. Segers, Pete Smith, Efisio Solazzo, Hanqin Tian, Francesco N. Tubiello, Timo Vesala, Guido R. van der Werf, Chris Wilson, and Sönke Zaehle
Earth Syst. Sci. Data, 15, 1197–1268, https://doi.org/10.5194/essd-15-1197-2023, https://doi.org/10.5194/essd-15-1197-2023, 2023
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This study updates the state-of-the-art scientific overview of CH4 and N2O emissions in the EU27 and UK in Petrescu et al. (2021a). Yearly updates are needed to improve the different respective approaches and to inform on the development of formal verification systems. It integrates the most recent emission inventories, process-based model and regional/global inversions, comparing them with UNFCCC national GHG inventories, in support to policy to facilitate real-time verification procedures.
Sourish Basu, Xin Lan, Edward Dlugokencky, Sylvia Michel, Stefan Schwietzke, John B. Miller, Lori Bruhwiler, Youmi Oh, Pieter P. Tans, Francesco Apadula, Luciana V. Gatti, Armin Jordan, Jaroslaw Necki, Motoki Sasakawa, Shinji Morimoto, Tatiana Di Iorio, Haeyoung Lee, Jgor Arduini, and Giovanni Manca
Atmos. Chem. Phys., 22, 15351–15377, https://doi.org/10.5194/acp-22-15351-2022, https://doi.org/10.5194/acp-22-15351-2022, 2022
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Atmospheric methane (CH4) has been growing steadily since 2007 for reasons that are not well understood. Here we determine sources of methane using a technique informed by atmospheric measurements of CH4 and its isotopologue 13CH4. Measurements of 13CH4 provide for better separation of microbial, fossil, and fire sources of methane than CH4 measurements alone. Compared to previous assessments such as the Global Carbon Project, we find a larger microbial contribution to the post-2007 increase.
Peter Bergamaschi, Arjo Segers, Dominik Brunner, Jean-Matthieu Haussaire, Stephan Henne, Michel Ramonet, Tim Arnold, Tobias Biermann, Huilin Chen, Sebastien Conil, Marc Delmotte, Grant Forster, Arnoud Frumau, Dagmar Kubistin, Xin Lan, Markus Leuenberger, Matthias Lindauer, Morgan Lopez, Giovanni Manca, Jennifer Müller-Williams, Simon O'Doherty, Bert Scheeren, Martin Steinbacher, Pamela Trisolino, Gabriela Vítková, and Camille Yver Kwok
Atmos. Chem. Phys., 22, 13243–13268, https://doi.org/10.5194/acp-22-13243-2022, https://doi.org/10.5194/acp-22-13243-2022, 2022
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We present a novel high-resolution inverse modelling system, "FLEXVAR", and its application for the inverse modelling of European CH4 emissions in 2018. The new system combines a high spatial resolution of 7 km x 7 km with a variational data assimilation technique, which allows CH4 emissions to be optimized from individual model grid cells. The high resolution allows the observations to be better reproduced, while the derived emissions show overall good consistency with two existing models.
Angharad C. Stell, Michael Bertolacci, Andrew Zammit-Mangion, Matthew Rigby, Paul J. Fraser, Christina M. Harth, Paul B. Krummel, Xin Lan, Manfredi Manizza, Jens Mühle, Simon O'Doherty, Ronald G. Prinn, Ray F. Weiss, Dickon Young, and Anita L. Ganesan
Atmos. Chem. Phys., 22, 12945–12960, https://doi.org/10.5194/acp-22-12945-2022, https://doi.org/10.5194/acp-22-12945-2022, 2022
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Nitrous oxide is a potent greenhouse gas and ozone-depleting substance, whose atmospheric abundance has risen throughout the contemporary record. In this work, we carry out the first global hierarchical Bayesian inversion to solve for nitrous oxide emissions. We derive increasing global nitrous oxide emissions over 2011–2020, which are mainly driven by emissions between 0° and 30°N, with the highest emissions recorded in 2020.
Maria Paula Pérez-Peña, Jenny A. Fisher, Dylan B. Millet, Hisashi Yashiro, Ray L. Langenfelds, Paul B. Krummel, and Scott H. Kable
Atmos. Chem. Phys., 22, 12367–12386, https://doi.org/10.5194/acp-22-12367-2022, https://doi.org/10.5194/acp-22-12367-2022, 2022
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We used two atmospheric models to test the implications of previously unexplored aldehyde photochemistry on the atmospheric levels of molecular hydrogen (H2). We showed that the new photochemistry from aldehydes produces more H2 over densely forested areas. Compared to the rest of the world, it is over these forested regions where the produced H2 is more likely to be removed. The results highlight that other processes that contribute to atmospheric H2 levels should be studied further.
Megan Jeramaz Lickley, John S. Daniel, Eric L. Fleming, Stefan Reimann, and Susan Solomon
Atmos. Chem. Phys., 22, 11125–11136, https://doi.org/10.5194/acp-22-11125-2022, https://doi.org/10.5194/acp-22-11125-2022, 2022
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Halocarbons contained in equipment continue to be emitted after production has ceased. These
banksmust be carefully accounted for in evaluating compliance with the Montreal Protocol. We extend a Bayesian model to the suite of regulated chemicals subject to banking. We find that banks are substantially larger than previous estimates, and we identify banks by chemical and equipment type whose future emissions will contribute to global warming and delay ozone-hole recovery if left unrecovered.
Luke M. Western, Alison L. Redington, Alistair J. Manning, Cathy M. Trudinger, Lei Hu, Stephan Henne, Xuekun Fang, Lambert J. M. Kuijpers, Christina Theodoridi, David S. Godwin, Jgor Arduini, Bronwyn Dunse, Andreas Engel, Paul J. Fraser, Christina M. Harth, Paul B. Krummel, Michela Maione, Jens Mühle, Simon O'Doherty, Hyeri Park, Sunyoung Park, Stefan Reimann, Peter K. Salameh, Daniel Say, Roland Schmidt, Tanja Schuck, Carolina Siso, Kieran M. Stanley, Isaac Vimont, Martin K. Vollmer, Dickon Young, Ronald G. Prinn, Ray F. Weiss, Stephen A. Montzka, and Matthew Rigby
Atmos. Chem. Phys., 22, 9601–9616, https://doi.org/10.5194/acp-22-9601-2022, https://doi.org/10.5194/acp-22-9601-2022, 2022
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The production of ozone-destroying gases is being phased out. Even though production of one of the main ozone-depleting gases, called HCFC-141b, has been declining for many years, the amount that is being released to the atmosphere has been increasing since 2017. We do not know for sure why this is. A possible explanation is that HCFC-141b that was used to make insulating foams many years ago is only now escaping to the atmosphere, or a large part of its production is not being reported.
Guus J. M. Velders, John S. Daniel, Stephen A. Montzka, Isaac Vimont, Matthew Rigby, Paul B. Krummel, Jens Muhle, Simon O'Doherty, Ronald G. Prinn, Ray F. Weiss, and Dickon Young
Atmos. Chem. Phys., 22, 6087–6101, https://doi.org/10.5194/acp-22-6087-2022, https://doi.org/10.5194/acp-22-6087-2022, 2022
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The emissions of hydrofluorocarbons (HFCs) have increased significantly in the past as a result of the phasing out of ozone-depleting substances. Observations indicate that HFCs are used much less in certain refrigeration applications than previously projected. Current policies are projected to reduce emissions and the surface temperature contribution of HFCs from 0.28–0.44 °C to 0.14–0.31 °C in 2100. The Kigali Amendment is projected to reduce the contributions further to 0.04 °C in 2100.
Haklim Choi, Mi-Kyung Park, Paul J. Fraser, Hyeri Park, Sohyeon Geum, Jens Mühle, Jooil Kim, Ian Porter, Peter K. Salameh, Christina M. Harth, Bronwyn L. Dunse, Paul B. Krummel, Ray F. Weiss, Simon O'Doherty, Dickon Young, and Sunyoung Park
Atmos. Chem. Phys., 22, 5157–5173, https://doi.org/10.5194/acp-22-5157-2022, https://doi.org/10.5194/acp-22-5157-2022, 2022
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We observed 12-year continuous CH3Br pollution signals at Gosan and estimated anthropogenic CH3Br emissions in eastern China. The analysis revealed a significant discrepancy between top-down estimates and the bottom-up emissions from the fumigation usage reported to the United Nations Environment Programme, likely due to unreported or inaccurately reported fumigation usage. This result provides information to monitor international compliance with the Montreal Protocol.
Alice E. Ramsden, Anita L. Ganesan, Luke M. Western, Matthew Rigby, Alistair J. Manning, Amy Foulds, James L. France, Patrick Barker, Peter Levy, Daniel Say, Adam Wisher, Tim Arnold, Chris Rennick, Kieran M. Stanley, Dickon Young, and Simon O'Doherty
Atmos. Chem. Phys., 22, 3911–3929, https://doi.org/10.5194/acp-22-3911-2022, https://doi.org/10.5194/acp-22-3911-2022, 2022
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Quantifying methane emissions from different sources is a key focus of current research. We present a method for estimating sectoral methane emissions that uses ethane as a tracer for fossil fuel methane. By incorporating variable ethane : methane emission ratios into this model, we produce emissions estimates with improved uncertainty characterisation. This method will be particularly useful for studying methane emissions in areas with complex distributions of sources.
Peter Sperlich, Gordon W. Brailsford, Rowena C. Moss, John McGregor, Ross J. Martin, Sylvia Nichol, Sara Mikaloff-Fletcher, Beata Bukosa, Magda Mandic, C. Ian Schipper, Paul Krummel, and Alan D. Griffiths
Atmos. Meas. Tech., 15, 1631–1656, https://doi.org/10.5194/amt-15-1631-2022, https://doi.org/10.5194/amt-15-1631-2022, 2022
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We tested an in situ analyser for carbon and oxygen isotopes in atmospheric CO2 at Baring Head, New Zealand’s observatory for Southern Ocean baseline air. The analyser was able to resolve regional signals of the terrestrial carbon cycle, although the analysis of small events was limited by analytical uncertainty. Further improvement of the instrument performance would be desirable for the robust analysis of distant signals and to resolve the small variability in Southern Ocean baseline air.
Eric Saboya, Giulia Zazzeri, Heather Graven, Alistair J. Manning, and Sylvia Englund Michel
Atmos. Chem. Phys., 22, 3595–3613, https://doi.org/10.5194/acp-22-3595-2022, https://doi.org/10.5194/acp-22-3595-2022, 2022
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Continuous measurements of atmospheric methane concentrations and its carbon-13 isotope have been made in central London since early 2018. These measurements were used to evaluate methane emissions reported in global and UK-specific emission inventories for the London area. Compared to atmospheric methane measurements from March 2018 to October 2020, both inventories are under-reporting natural gas leakage for the London area.
Jens Mühle, Lambert J. M. Kuijpers, Kieran M. Stanley, Matthew Rigby, Luke M. Western, Jooil Kim, Sunyoung Park, Christina M. Harth, Paul B. Krummel, Paul J. Fraser, Simon O'Doherty, Peter K. Salameh, Roland Schmidt, Dickon Young, Ronald G. Prinn, Ray H. J. Wang, and Ray F. Weiss
Atmos. Chem. Phys., 22, 3371–3378, https://doi.org/10.5194/acp-22-3371-2022, https://doi.org/10.5194/acp-22-3371-2022, 2022
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Emissions of the strong greenhouse gas perfluorocyclobutane (c-C4F8) into the atmosphere have been increasing sharply since the early 2000s. These c-C4F8 emissions are highly correlated with the amount of hydrochlorofluorocarbon-22 produced to synthesize polytetrafluoroethylene (known for its non-stick properties) and related chemicals. From this process, c-C4F8 by-product is vented to the atmosphere. Avoiding these unnecessary c-C4F8 emissions could reduce the climate impact of this industry.
Dominique Rust, Ioannis Katharopoulos, Martin K. Vollmer, Stephan Henne, Simon O'Doherty, Daniel Say, Lukas Emmenegger, Renato Zenobi, and Stefan Reimann
Atmos. Chem. Phys., 22, 2447–2466, https://doi.org/10.5194/acp-22-2447-2022, https://doi.org/10.5194/acp-22-2447-2022, 2022
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Artificial halocarbons contribute to ozone layer depletion and to global warming. We measured the atmospheric concentrations of halocarbons at the Beromünster tower, modelled the Swiss emissions, and compared the results to the internationally reported Swiss emissions inventory. For most of the halocarbons, we found good agreement, whereas one refrigerant might be overestimated in the inventory. In addition, we present first emission estimates of the newest types of halocarbons.
Andrew Zammit-Mangion, Michael Bertolacci, Jenny Fisher, Ann Stavert, Matthew Rigby, Yi Cao, and Noel Cressie
Geosci. Model Dev., 15, 45–73, https://doi.org/10.5194/gmd-15-45-2022, https://doi.org/10.5194/gmd-15-45-2022, 2022
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We present a framework for estimating the sources and sinks (flux) of carbon dioxide from satellite data. The framework is statistical and yields measures of uncertainty alongside all estimates of flux and other parameters in the underlying model. It also allows us to generate other insights, such as the size of errors and biases in the data. The primary aim of this research was to develop a fully statistical flux inversion framework for use by atmospheric scientists.
Jan C. Minx, William F. Lamb, Robbie M. Andrew, Josep G. Canadell, Monica Crippa, Niklas Döbbeling, Piers M. Forster, Diego Guizzardi, Jos Olivier, Glen P. Peters, Julia Pongratz, Andy Reisinger, Matthew Rigby, Marielle Saunois, Steven J. Smith, Efisio Solazzo, and Hanqin Tian
Earth Syst. Sci. Data, 13, 5213–5252, https://doi.org/10.5194/essd-13-5213-2021, https://doi.org/10.5194/essd-13-5213-2021, 2021
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We provide a synthetic dataset on anthropogenic greenhouse gas (GHG) emissions for 1970–2018 with a fast-track extension to 2019. We show that GHG emissions continued to rise across all gases and sectors. Annual average GHG emissions growth slowed, but absolute decadal increases have never been higher in human history. We identify a number of data gaps and data quality issues in global inventories and highlight their importance for monitoring progress towards international climate goals.
Mark F. Lunt, Alistair J. Manning, Grant Allen, Tim Arnold, Stéphane J.-B. Bauguitte, Hartmut Boesch, Anita L. Ganesan, Aoife Grant, Carole Helfter, Eiko Nemitz, Simon J. O'Doherty, Paul I. Palmer, Joseph R. Pitt, Chris Rennick, Daniel Say, Kieran M. Stanley, Ann R. Stavert, Dickon Young, and Matt Rigby
Atmos. Chem. Phys., 21, 16257–16276, https://doi.org/10.5194/acp-21-16257-2021, https://doi.org/10.5194/acp-21-16257-2021, 2021
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We present an evaluation of the UK's methane emissions between 2013 and 2020 using a network of tall tower measurement sites. We find emissions that are consistent in both magnitude and trend with the UK's reported emissions, with a declining trend driven by a decrease in emissions from England. The impact of various components of the modelling set-up on these findings are explored through a number of sensitivity studies.
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Fillola, E., Santos-Rodriguez, R., Manning, A., O'Doherty, S., and Rigby, M.: A machine learning emulator for Lagrangian particle dispersion model footprints: a case study using NAME, Geosci. Model Dev., 16, 1997–2009, https://doi.org/10.5194/gmd-16-1997-2023, 2023. a, b, c, d
Fillola, E., Santos-Rodriguez, R., Tunnicliffe, R., Clark, J. N., Keshtmand, N., Ganesan, A., and Rigby, M.: Enabling fast greenhouse gas emissions inference from satellites with GATES: a Graph-Neural-Network Atmospheric Transport Emulation System, Geosci. Model Dev., 19, 1893–1915, https://doi.org/10.5194/gmd-19-1893-2026, 2026. a
Gerrand, K., Fillola Mayoral, E., and Rigby, M.: A Machine Learning Method for Estimating Atmospheric Trace Gas Concentration Baselines: Code repository, Zenodo [computer software], https://doi.org/10.5281/zenodo.20484075, 2026a. a
Gerrand, K., Fillola Mayoral, E., Manning, A., and Rigby, M.: A Machine Learning Method for Estimating Atmospheric Trace Gas Concentration Baselines: Training Data, Zenodo [data set], https://doi.org/10.5281/zenodo.20483977, 2026b a
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Henne, S., Klausen, J., Junkermann, W., Kariuki, J. M., Aseyo, J. O., and Buchmann, B.: Representativeness and climatology of carbon monoxide and ozone at the global GAW station Mt. Kenya in equatorial Africa, Atmos. Chem. Phys., 8, 3119–3139, https://doi.org/10.5194/acp-8-3119-2008, 2008. a
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Lunt, M. F., Rigby, M., Ganesan, A. L., and Manning, A. J.: Estimation of trace gas fluxes with objectively determined basis functions using reversible-jump Markov chain Monte Carlo, Geosci. Model Dev., 9, 3213–3229, https://doi.org/10.5194/gmd-9-3213-2016, 2016. a
Lunt, M. F., Manning, A. J., Allen, G., Arnold, T., Bauguitte, S. J.-B., Boesch, H., Ganesan, A. L., Grant, A., Helfter, C., Nemitz, E., O'Doherty, S. J., Palmer, P. I., Pitt, J. R., Rennick, C., Say, D., Stanley, K. M., Stavert, A. R., Young, D., and Rigby, M.: Atmospheric observations consistent with reported decline in the UK's methane emissions (2013–2020), Atmos. Chem. Phys., 21, 16257–16276, https://doi.org/10.5194/acp-21-16257-2021, 2021. a
Lööv, J. M. B., Henne, S., Legreid, G., Staehelin, J., Reimann, S., Prévôt, A. S., Steinbacher, M., and Vollmer, M. K.: Estimation of background concentrations of trace gases at the Swiss Alpine site Jungfraujoch (3580 m asl), J. Geophys. Res.-Atmos., 113, D22305, https://doi.org/10.1029/2007JD009751, 2008. a
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Prinn, R. G., Weiss, R. F., Arduini, J., Arnold, T., DeWitt, H. L., Fraser, P. J., Ganesan, A. L., Gasore, J., Harth, C. M., Hermansen, O., Kim, J., Krummel, P. B., Li, S., Loh, Z. M., Lunder, C. R., Maione, M., Manning, A. J., Miller, B. R., Mitrevski, B., Mühle, J., O'Doherty, S., Park, S., Reimann, S., Rigby, M., Saito, T., Salameh, P. K., Schmidt, R., Simmonds, P. G., Steele, L. P., Vollmer, M. K., Wang, R. H., Yao, B., Yokouchi, Y., Young, D., and Zhou, L.: History of chemically and radiatively important atmospheric gases from the Advanced Global Atmospheric Gases Experiment (AGAGE), Earth Syst. Sci. Data, 10, 985–1018, https://doi.org/10.5194/essd-10-985-2018, 2018. a, b
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Short summary
To analyse long-term trends in atmospheric trace gas concentrations, it is important to identify data points minimally affected by local pollution sources or air masses carried from other latitudes or altitudes. Traditional methods for detecting these “baselines” are computationally expensive or lack a basis in physical principles. This paper introduces a machine-learning method that uses meteorological data and offers significantly lower computational costs compared to physics-based techniques.
To analyse long-term trends in atmospheric trace gas concentrations, it is important to identify...
