scholarly journals What do we know about the global methane budget? Results from four decades of atmospheric CH 4 observations and the way forward

2021 ◽  
Vol 379 (2210) ◽  
pp. 20200440
Author(s):  
Xin Lan ◽  
Euan G. Nisbet ◽  
Edward J. Dlugokencky ◽  
Sylvia E. Michel
Keyword(s):  
Greenhouse Gases ◽  
Hydroxyl Radical ◽  
The State ◽  
Atmospheric Oxidation ◽  
Complete Understanding ◽  
Air Samples ◽  
Sources And Sinks ◽  
Methane Budget ◽  
Direct Measurements ◽  
Background Air

Atmospheric CH 4 is arguably the most interesting of the anthropogenically influenced, long-lived greenhouse gases. It has a diverse suite of sources, each presenting its own challenges in quantifying emissions, and while its main sink, atmospheric oxidation initiated by reaction with hydroxyl radical (OH), is well-known, determining the magnitude and trend in this and other smaller sinks remains challenging. Here, we provide an overview of the state of knowledge of the dynamic atmospheric CH 4 budget of sources and sinks determined from measurements of CH 4 and δ 13 C CH4 in air samples collected predominantly at background air sampling sites. While nearly four decades of direct measurements provide a strong foundation of understanding, large uncertainties in some aspects of the global CH 4 budget still remain. More complete understanding of the global CH 4 budget requires significantly more observations, not just of CH 4 itself, but other parameters to better constrain key, but still uncertain, processes like wetlands and sinks. This article is part of a discussion meeting issue 'Rising methane: is warming feeding warming? (part 1)'.

scholarly journals On the role of trend and variability in the hydroxyl radical (OH) in the global methane budget

2020 ◽  
Vol 20 (21) ◽  
pp. 13011-13022
Author(s):  
Yuanhong Zhao ◽  
Marielle Saunois ◽  
Philippe Bousquet ◽  
Xin Lin ◽  
Antoine Berchet ◽  
...  
Keyword(s):  
Hydroxyl Radical ◽  
El Niño ◽  
Climate Model ◽  
El Nino ◽  
Interannual Variations ◽  
Atmospheric Methane ◽  
Tropical Regions ◽  
Ch4 Emissions ◽  
Methane Budget

Abstract. Decadal trends and interannual variations in the hydroxyl radical (OH), while poorly constrained at present, are critical for understanding the observed evolution of atmospheric methane (CH4). Through analyzing the OH fields simulated by the model ensemble of the Chemistry–Climate Model Initiative (CCMI), we find (1) the negative OH anomalies during the El Niño years mainly corresponding to the enhanced carbon monoxide (CO) emissions from biomass burning and (2) a positive OH trend during 1980–2010 dominated by the elevated primary production and the reduced loss of OH due to decreasing CO after 2000. Both two-box model inversions and variational 4D inversions suggest that ignoring the negative anomaly of OH during the El Niño years leads to a large overestimation of the increase in global CH4 emissions by up to 10 ± 3 Tg yr−1 to match the observed CH4 increase over these years. Not accounting for the increasing OH trends given by the CCMI models leads to an underestimation of the CH4 emission increase by 23 ± 9 Tg yr−1 from 1986 to 2010. The variational-inversion-estimated CH4 emissions show that the tropical regions contribute most to the uncertainties related to OH. This study highlights the significant impact of climate and chemical feedbacks related to OH on the top-down estimates of the global CH4 budget.

scholarly journals Atmospheric Chemistry, Sources, and Sinks of Carbon Suboxide, C<sub>3</sub>O<sub>2</sub>

2017 ◽  
Author(s):  
Stephan Keßel ◽  
David Cabrera-Perez ◽  
Abraham Horowitz ◽  
Patrick R. Veres ◽  
Rolf Sander ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Relative Rate ◽  
Ambient Air ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Carbon Suboxide ◽  
Air Samples ◽  
Sources And Sinks

Abstract. Carbon suboxide, O = C = C = C = O, has been detected in ambient air samples and has the potential to be a noxious pollutant and oxidant precursor; however, its lifetime and fate in the atmosphere is largely unknown. In this work, we collect an extensive set of studies on the atmospheric chemistry of C3O2. Rate coefficients for the reactions of C3O2 with OH radicals and ozone were determined using relative rate techniques as k4 = (2.6 ± 0.5) × 10−12 cm3 molecule−1 s1 at 295 K (independent of pressure between ~ 25 and 1000 mbar) and k6 

scholarly journals Simultaneous shipborne measurements of CO<sub>2</sub>, CH<sub>4</sub> and CO and their application to improving greenhouse-gas flux estimates in Australia

2019 ◽  
Vol 19 (10) ◽  
pp. 7055-7072 ◽  
Author(s):  
Beata Bukosa ◽  
Nicholas M. Deutscher ◽  
Jenny A. Fisher ◽  
Dagmar Kubistin ◽  
Clare Paton-Walsh ◽  
...  
Keyword(s):  
Greenhouse Gases ◽  
Greenhouse Gas ◽  
Biomass Burning ◽  
Greenhouse Gas Emission ◽  
Anthropogenic Sources ◽  
Climate Feedback ◽  
Eastern Coast ◽  
Sources And Sinks ◽  
Australian Continent ◽  
Carbon Gases

Abstract. Quantitative understanding of the sources and sinks of greenhouse gases is essential for predicting greenhouse-gas–climate feedback processes and their impacts on climate variability and change. Australia plays a significant role in driving variability in global carbon cycling, but the budgets of carbon gases in Australia remain highly uncertain. Here, shipborne Fourier transform infrared spectrometer measurements collected around Australia are used together with a global chemical transport model (GEOS-Chem) to analyse the variability of three direct and indirect carbon greenhouse gases: carbon dioxide (CO2), methane (CH4) and carbon monoxide (CO). Using these measurements, we provide an updated distribution of these gases. From the model, we quantify their sources and sinks, and we exploit the benefits of multi-species analysis to explore co-variations to constrain relevant processes. We find that for all three gases, the eastern Australian coast is largely influenced by local anthropogenic sources, while the southern, western and northern coasts are characterised by a mixture of anthropogenic and natural sources. Comparing coincident and co-located enhancements in the three carbon gases highlighted several common sources from the Australian continent. We found evidence for 17 events with similar enhancement patterns indicative of co-emission and calculated enhancement ratios and modelled source contributions for each event. We found that anthropogenic co-enhancement events are common along the eastern coast, while co-enhancement events in the tropics primarily derive from biomass burning sources. While the GEOS-Chem model generally reproduced the timing of co-enhancement events, it was less able to reproduce the magnitude of enhancements. We used these differences to identify underestimated, overestimated and missing processes in the model. We found model overestimates of CH4 from coal burning and underestimates of all three gases from biomass burning. We identified missing sources from fossil fuel, biofuel, oil, gas, coal, livestock, biomass burning and the biosphere in the model, pointing to the need to further develop and evaluate greenhouse-gas emission inventories for the Australian continent.

scholarly journals In situ observations of greenhouse gases over Europe during the CoMet 1.0 campaign aboard the HALO aircraft

2020 ◽  
Author(s):  
Michał Gałkowski ◽  
Armin Jordan ◽  
Michael Rothe ◽  
Julia Marshall ◽  
Frank-Thomas Koch ◽  
...  
Keyword(s):  
Greenhouse Gases ◽  
Isotopic Signature ◽  
Standard Uncertainty ◽  
The European Union ◽  
Air Samples ◽  
Mixing Ratios ◽  
Regional Sources ◽  
Research Aircraft ◽  
In Situ Observations

Abstract. The intensive measurement campaign CoMet 1.0 (Carbon dioxide and Methane mission) took place during May and June 2018, with a focus on greenhouse gases over Europe. CoMet 1.0 aimed at characterising the distribution of CH4 and CO2 over significant regional sources with the use of a fleet of research aircraft, as well as validating remote sensing measurements from state-of-the-art instrumentation installed on-board against a set of independent in-situ observations. Here we present the results of over 55 hours of accurate and precise in situ measurements of CO2, CH4 and CO mixing ratios made during CoMet 1.0 flights with a cavity ring-down spectrometer aboard the German research aircraft HALO, together with results from analyses of 96 discrete air samples collected aboard the same platform. A careful in-flight calibration strategy together with post-flight quality assessment made it possible to determine both the single measurement precision as well as biases against respective WMO scales. We compare the result of greenhouse gas observations against two of the available global modelling systems, namely Jena CarboScope and CAMS (Copernicus Atmosphere Monitoring Service). We find overall good agreement between the global models and the observed mixing ratios in the free-tropospheric range, characterised by very low bias values for the CAMS CH4 and the CarboScope CO2 products, with a mean free tropospheric offset of 0 (14) ppb and 0.8 (1.3) ppm respectively, with the quoted number giving the standard uncertainty in the final digits for the numerical value. Higher bias is observed for CAMS CO2 (equal to 3.7 (1.5) ppm), and for CO the model-observation mismatch is variable with height (with offset equal to −1.0 (8.8)). We also present laboratory analyses of air samples collected throughout the flights, which include information on the isotopic composition of CH_4, and we demonstrate the potential of simultaneously measuring δ13C-CH4 and δ2H-CH4 from air to determine the sources of enhanced methane signals using even a limited amount of discrete samples. Using flasks collected during two flights over the Upper Silesian Coal Basin (USCB, southern Poland), one of the strongest methane-emitting regions in the European Union, we were able to use the Miller-Tans approach to derive the isotopic signature of the measured source, with values of δ2H equal to −224.7 (6.6) permil and δ13C to −50.9 (1.1) permil, giving significantly lower d2H values compared to previous studies in the area.

scholarly journals Comparisons of continuous atmospheric CH<sub>4</sub>, CO<sub>2</sub> and N<sub>2</sub>O measurements – results of InGOS travelling instrument campaign at Mace Head

2014 ◽  
Vol 14 (7) ◽  
pp. 10429-10462 ◽  
Author(s):  
S. N. Vardag ◽  
S. Hammer ◽  
S. O'Doherty ◽  
T. G. Spain ◽  
B. Wastine ◽  
...  
Keyword(s):  
Greenhouse Gases ◽  
Evaluation Process ◽  
Ambient Air ◽  
Measurement Campaign ◽  
Direct Measurements ◽  
Before And After ◽  
The Difference ◽  
Ch4 And N2o ◽  
And Performance ◽  
Gas Cylinders

Abstract. A two-month measurement campaign with a Fourier Transform InfraRed (FTIR) analyser as a Travelling Comparison Instrument (TCI) was performed at the AGAGE and WMO GAW station Mace Head, Ireland. The aim was to evaluate the compatibility of atmospheric CH4, CO2 and N2O measurements of the routine station instrumentation, consisting of a gas chromatograph (GC-MD) for CH4 and N2O as well as a cavity ring-down spectroscopy (CRDS) system for CH4 and CO2. The advantage of a TCI approach for quality control is that the comparison covers the entire ambient air measurement system, including the sample intake system and the data evaluation process. For initial quality and performance control the TCI was run in parallel to the Heidelberg GC (GC-HEI) before and after the measurement campaign at Mace Head. Median differences between the GC-HEI and the TCI were well within the WMO Inter Laboratory Compatibility (ILC) target for all three greenhouse gases. At Mace Head, the median difference between the GC-MD and the TCI were −0.04 nmol mol−1 for CH4 and −0.37 nmol mol−1 for N2O. For N2O a similar difference (−0.40 nmol mol−1) was found when measuring surveillance or working gas cylinders with both instruments. This suggests that the difference observed in ambient air originates from a calibration offset that could partly be due to a difference between the WMO N2O X2006a scale used for the TCI and the SIO-1998 scale used at Mace Head and in the whole AGAGE network. Median differences between the CRDS G1301 and the TCI at Mace Head were 0.12 nmol mol−1 for CH4 and 0.14 μmol mol−1 for CO2 (CRDS G1301 − TCI). The difference between both instruments for CO2 could not be explained, as direct measurements of calibration gases show no such difference. The CH4 differences between the TCI, the GC-MD and the CRDS G1301 at Mace Head are smaller than the WMO Inter Laboratory compatibility (ILC) target (WMO, 2009), while this is not the case for CO2 and N2O. During the campaign it was also demonstrated that the new optical instrumentation allows detection of very small vertical CO2 and CH4 gradients, here between 10 m a.g.l. and 25 m a.g.l. This provides a new opportunity of evaluating greenhouse gases gradients in terms of regional fluxes.

scholarly journals In situ observations of greenhouse gases over Europe during the CoMet 1.0 campaign aboard the HALO aircraft

2021 ◽  
Vol 14 (2) ◽  
pp. 1525-1544
Author(s):  
Michał Gałkowski ◽  
Armin Jordan ◽  
Michael Rothe ◽  
Julia Marshall ◽  
Frank-Thomas Koch ◽  
...  
Keyword(s):  
Greenhouse Gases ◽  
Isotopic Signature ◽  
Standard Uncertainty ◽  
The European Union ◽  
Air Samples ◽  
Regional Sources ◽  
Research Aircraft ◽  
In Situ Observations ◽  
Monitoring Service

Abstract. The intensive measurement campaign CoMet 1.0 (Carbon Dioxide and Methane Mission) took place during May and June 2018, with a focus on greenhouse gases over Europe. CoMet 1.0 aimed at characterising the distribution of CH4 and CO2 over significant regional sources with the use of a fleet of research aircraft as well as validating remote sensing measurements from state-of-the-art instrumentation installed on board against a set of independent in situ observations. Here we present the results of over 55 h of accurate and precise in situ measurements of CO2, CH4 and CO mole fractions made during CoMet 1.0 flights with a cavity ring-down spectrometer aboard the German research aircraft HALO (High Altitude and LOng Range Research Aircraft), together with results from analyses of 96 discrete air samples collected aboard the same platform. A careful in-flight calibration strategy together with post-flight quality assessment made it possible to determine both the single-measurement precision as well as biases against respective World Meteorological Organization (WMO) scales. We compare the result of greenhouse gas observations against two of the available global modelling systems, namely Jena CarboScope and CAMS (Copernicus Atmosphere Monitoring Service). We find overall good agreement between the global models and the observed mole fractions in the free tropospheric range, characterised by very low bias values for the CAMS CH4 and the CarboScope CO2 products, with a mean free tropospheric offset of 0 (14) nmol mol−1 and 0.8 (1.3) µmol mol−1 respectively, with the numbers in parentheses giving the standard uncertainty in the final digits for the numerical value. Higher bias is observed for CAMS CO2 (equal to 3.7 (1.5) µmol mol−1), and for CO the model–observation mismatch is variable with height (with offset equal to −1.0 (8.8) nmol mol−1). We also present laboratory analyses of air samples collected throughout the flights, which include information on the isotopic composition of CH4, and we demonstrate the potential of simultaneously measuring δ13C−CH4 and δ2H−CH4 from air to determine the sources of enhanced methane signals using even a limited number of discrete samples. Using flasks collected during two flights over the Upper Silesian Coal Basin (USCB, southern Poland), one of the strongest methane-emitting regions in the European Union, we were able to use the Miller–Tans approach to derive the isotopic signature of the measured source, with values of δ2H equal to −224.7 (6.6) ‰ and δ13C to −50.9 (1.1) ‰, giving significantly lower δ2H values compared to previous studies in the area.

scholarly journals Methane emissions from coal open pits in Colombia

DYNA ◽  
2020 ◽  
Vol 87 (214) ◽  
pp. 139-145
Author(s):  
Jorge Eliecer Mariño Martínez ◽  
Ruben Darío Chanci Bedoya ◽  
Angélica Julieth Gonzalez Preciado
Keyword(s):  
Climate Change ◽  
Greenhouse Gases ◽  
Open Pit ◽  
Open Pit Mining ◽  
Fugitive Emissions ◽  
Coal Beds ◽  
Direct Measurements ◽  
Co2 Equivalent ◽  
Level 1 ◽  
Level 2

From the agreements on climate change Colombia is committed to measuring and reporting emissions of greenhouse gases (GHG), and among these, the coal mining fugitive emissions. The country has been reporting emissions from international tables-Level 1 of the IPCC, but this proposal is suggesting doing so from exploration of CBM-Level 2 using canisters desorption systems. For the Colombia open pit mining (provinces of Guajira and Cesar) the analyses from international tables and from CBM studies found that emissions from tables-Level 1 (106.02 Gg of methane) exceed the content found in direct measurements-Level 2 (75.92 Gg of methane) in 40%. The levels of emissions in tons of CO2 equivalent are 2.226.420 and 1.594.320 tons respectively. These results show that since the contents of methane of Colombian coal beds are lower compared with main coal-producing countries, the fugitive emissions from the extraction of coal in Colombia should be calculated from CBM studies.

scholarly journals Improved isotopic characterisation of methane emissions from biomass burning

2020 ◽  
Author(s):  
Rebecca Fisher ◽  
Euan Nisbet ◽  
James France ◽  
Amber Riddle ◽  
David Lowry ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Biomass Burning ◽  
Plant Material ◽  
Atmospheric Methane ◽  
Regional Variability ◽  
Global Models ◽  
C3 Plant ◽  
Air Samples ◽  
Fire Emissions ◽  
Methane Budget

&lt;p&gt;Emissions of methane from combustion sources are typically distinguished by being enriched in &lt;sup&gt;13&lt;/sup&gt;C and &lt;sup&gt;2&lt;/sup&gt;H, causing a large isotopic shift to atmospheric methane &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C and &amp;#948;D measurements downwind of fires.&lt;/p&gt;&lt;p&gt;The isotopic composition of the plant material being burnt has a strong effect on the isotopic composition of methane, with combustion of C4 plant material producing methane more enriched in &lt;sup&gt;13&lt;/sup&gt;C than C3 plant combustion. Characterisation of the bulk isotopic signature of methane emitted from large areas of biomass burning is required to improve our ability to use isotopes in global models and ascertain the extent to which fire emissions influence interannual variations in the methane budget.&lt;/p&gt;&lt;p&gt;Two approaches have been used to collect air samples from large areas of biomass burning for isotopic characterisation of methane emitted from the fires. In campaigns in Senegal, Uganda, Zambia and Finland, the UK&amp;#8217;s FAAM research aircraft flew through fire plumes and onboard measurement of methane concentration allowed targeted sampling within the plumes. This work was carried out as part of the NERC highlight Global Methane Budget project (MOYA). Ground based sampling downwind of fires around Sydney, New South Wales in late 2019/early 2020 has allowed isotopic characterisation of those plumes. All air samples were measured by isotope ratio mass spectrometry at Royal Holloway University of London and Keeling plots used to identify source signatures, e.g. &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C for fires in Senegal in March 2017 was -28.5 &amp;#177; 0,8 , typical of C3 burning.&lt;/p&gt;&lt;p&gt;In this work we compare the isotopic signatures of methane from burning in these particular regions and discuss the extent to which the regional variability of the isotopic composition of fire emissions should be taken into account in global models using isotopes to constrain the global methane budget.&lt;/p&gt;

Nationalism, Citizenship, and Gender

2011 ◽  
Author(s):  
Joyce P. Kaufman ◽  
Kristen P. Williams
Keyword(s):  
Comparative Politics ◽  
The State ◽  
Future Research ◽  
Complete Understanding ◽  
Sovereign State ◽  
Feminist Literature ◽  
The Public ◽  
Socially Constructed ◽  
And Gender ◽  
Shed Light

Nationalism and the nation-state are both intimately connected to citizenship. Citizenship and nationalism are also linked to gender, as all three concepts play a key role in the process of state-building and state-maintenance as well as in the interaction between states, whether overtly or covertly. Yet women do not figure in the analysis of nationalism and citizenship in the mainstream literature, a gap that feminists have been trying to fill. By interrogating gender, along with the notions of masculinity and femininity, feminist international relations (IR) scholars shed light into the ways that gender is socially constructed. They also investigate the historical process of state formation and show where women are located in nationalist movements. Furthermore, by unpacking the sovereign state, feminist scholars have argued that while mainstream IR views the state as a rational, unitary actor, states are actually gendered entities. Two kinds of feminist literature in IR in regards to the state can be identified: women and the state (how women are excluded in terms of the public–private divide, and through citizenship), and gender and the state (gendered states). In general, feminist scholarship has led to a more complete understanding of the gender-citizenship-nationalism nexus. Nevertheless, some avenues for future research deserve consideration, such as the political and cultural exclusions of women and others in society, the inequalities that exist within states, whether there is such a thing as a “Comparative Politics of Gender,” and the concept of “global citizenship.”

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