Radiocarbon determination of atmospheric methane at Baring Head, New Zealand

Lowe, David C.; Brenninkmeijer, Carl A. M.; Manning, Martin; Sparks, R. J.; Wallace, G.

doi:10.1038/332522a0

Cited by 103 publications

(53 citation statements)

References 19 publications

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“…Emissions also show substantial differences in δD(CH 4 ) isotopic signatures: −200 ‰ for biomass burning sources vs. −360 to −250 ‰ for biogenic sources (Melton et al, 2012;Quay et al, 1999). 14 C-CH 4 measurements (Quay et al, 1991(Quay et al, , 1999Lowe et al, 1988) may also help to partition for fossil fuel contribution (radiocarbon-free source). For example, Lassey et al (2007a) used more than 200 measurements of radioactive 14 C-CH 4 (with a balanced weight between Northern and Southern hemispheres) to further constrain the fossil fuel contribution to the global methane source emission to 30 ± 2 % for the period 1986-2000.…”

Section: Methane Isotope Observationsmentioning

confidence: 99%

The global methane budget 2000–2012

Saunois

Bousquet

Poulter

et al. 2016

Earth Syst. Sci. Data

934

733

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Abstract. The global methane (CH 4 ) budget is becoming an increasingly important component for managing realistic pathways to mitigate climate change. This relevance, due to a shorter atmospheric lifetime and a stronger warming potential than carbon dioxide, is challenged by the still unexplained changes of atmospheric CH 4 over the past decade. Emissions and concentrations of CH 4 are continuing to increase, making CH 4 the second most important human-induced greenhouse gas after carbon dioxide. Two major difficulties in reducing uncertainties come from the large variety of diffusive CH 4 sources that overlap geographically, and from the destruction of CH 4 by the very short-lived hydroxyl radical (OH). To address these difficulties, we have established a consortium of multi-disciplinary scientists under the umbrella of the Global Carbon Project to synthesize and stimulate research on the methane cycle, and producing regular (∼ biennial) updates of the global methane budget. This consortium includes atmospheric physicists and chemists, biogeochemists of surface and marine emissions, and socio-economists who study anthropogenic emissions. Following Kirschke et al. (2013), we propose here the first version of a living review paper that integrates results of top-down studies (exploiting atmospheric observations within an atmospheric inverse-modelling framework) and bottom-up models, inventories and data-driven approaches (including process-based models for estimating land surface emissions and atmospheric chemistry, and inventories for anthropogenic emissions, data-driven extrapolations). . Top-down inversions consistently infer lower emissions in China (∼ 58 Tg CH 4 yr −1 , range 51-72, −14 %) and higher emissions in Africa (86 Tg CH 4 yr −1 , range 73-108, +19 %) than bottom-up values used as prior estimates. Overall, uncertainties for anthropogenic emissions appear smaller than those from natural sources, and the uncertainties on source categories appear larger for top-down inversions than for bottom-up inventories and models.The most important source of uncertainty on the methane budget is attributable to emissions from wetland and other inland waters. We show that the wetland extent could contribute 30-40 % on the estimated range for wetland emissions. Other priorities for improving the methane budget include the following: (i) the development of process-based models for inland-water emissions, (ii) the intensification of methane observations at local scale (flux measurements) to constrain bottom-up land surface models, and at regional scale (surface networks and satellites) to constrain top-down inversions, (iii) improvements in the estimation of atmospheric loss by OH, and (iv) improvements of the transport models integrated in top-down inversions.

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Section: Methane Isotope Observationsmentioning

confidence: 99%

The global methane budget 2000–2012

Saunois

Bousquet

Poulter

et al. 2016

Earth Syst. Sci. Data

934

733

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“…The National Institute for Water and Atmospheric Research (NIWA, originally INS (Institute of Nuclear Sciences) and later INGS (Institute of Nuclear and Geological Sciences) until 1992) successfully initiated systematic measurements of atmospheric δ 13 C-CH 4 by means of offline CH 4 separation and conversion followed by a DI-IRMS measurement in 1988 (Lowe et al, 1988(Lowe et al, , 1991. A suite of CO 2 working gases with δ 13 C-CH 4 values around −47 ‰ referenced to IAEA materials were utilized to calibrate the measurements.…”

Section: Niwamentioning

confidence: 99%

Interlaboratory comparison of δ13C and δD measurements of atmospheric CH4 for combined use of data sets from different laboratories

et al. 2018

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Abstract. We report results from a worldwide interlaboratory comparison of samples among laboratories that measure (or measured) stable carbon and hydrogen isotope ratios of atmospheric CH 4 (δ 13 C-CH 4 and δD-CH 4 ). The offsets among the laboratories are larger than the measurement reproducibility of individual laboratories. To disentangle plausible measurement offsets, we evaluated and critically assessed a large number of intercomparison results, some of which have been documented previously in the literature. The results indicate significant offsets of δ 13 C-CH 4 and δD-CH 4 measurements among data sets reported from different laboratories; the differences among laboratories at modern atmospheric CH 4 level spread over ranges of 0.5 ‰ for δ 13 C-CH 4 and 13 ‰ for δD-CH 4 . The intercomparison results summarized in this study may be of help in future attempts to harmonize δ 13 C-CH 4 and δD-CH 4 data sets fromPublished by Copernicus Publications on behalf of the European Geosciences Union. 1208T. Umezawa et al.: Interlaboratory comparison of δ 13 C and δD measurements of CH 4 different laboratories in order to jointly incorporate them into modelling studies. However, establishing a merged data set, which includes δ 13 C-CH 4 and δD-CH 4 data from multiple laboratories with desirable compatibility, is still challenging due to differences among laboratories in instrument settings, correction methods, traceability to reference materials and long-term data management. Further efforts are needed to identify causes of the interlaboratory measurement offsets and to decrease those to move towards the best use of available δ 13 C-CH 4 and δD-CH 4 data sets.

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“…A fossil fuel component is present in the atmospheric methane cycle and has been estimated to be in the 20-30% range by 14C measurements [Wahlen et al, 1989;Lowe et al, 1988;Manning et al, 1990;Houghton et al, 1994]. This component is attributed to loss during production, distribution, and use of petroleum products and natural gas.…”

Section: Introductionmentioning

confidence: 99%

Natural microseepage of methane to the atmosphere from the Denver‐Julesburg basin, Colorado

Klusman¹,

Jakel²

1998

J. Geophys. Res.

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Abstract. Methane fluxes were measured at locations across the Denver-Julesburg (DJ) basin of northeastern Colorado, which is in a semiarid climate. There is a potential for microseepage of thermogenically derived methane and light hydrocarbons to the atmosphere, which during drier or colder seasons may exceed the capacity for methanotrophic oxidation in the shallow soils. Triplicate measurements of methane flux in three seasons across the basin found areas of positive and negative fluxes in a patchy pattern which averaged +0.57 mg CH 4 m -2 d -1. The possibility of drier areas of the continents, which are underlain by thick sedimentary units seasonally producing positive methane fluxes to the atmosphere, represents a second-order effect in the estimation of the terrestrial sources/sinks for atmospheric methane. The chambers were operated in a static mode, shaded from the Sun, and air under the chamber mixed using an externally 28,041

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Radiocarbon determination of atmospheric methane at Baring Head, New Zealand

Cited by 103 publications

References 19 publications

The global methane budget 2000–2012

The global methane budget 2000–2012

Interlaboratory comparison of <i>δ</i><sup>13</sup>C and <i>δ</i>D measurements of atmospheric CH<sub>4</sub> for combined use of data sets from different laboratories

Natural microseepage of methane to the atmosphere from the Denver‐Julesburg basin, Colorado

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Radiocarbon determination of atmospheric methane at Baring Head, New Zealand

Cited by 103 publications

References 19 publications

The global methane budget 2000–2012

The global methane budget 2000–2012

Interlaboratory comparison of &lt;i&gt;δ&lt;/i&gt;&lt;sup&gt;13&lt;/sup&gt;C and &lt;i&gt;δ&lt;/i&gt;D measurements of atmospheric CH&lt;sub&gt;4&lt;/sub&gt; for combined use of data sets from different laboratories

Natural microseepage of methane to the atmosphere from the Denver‐Julesburg basin, Colorado

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Interlaboratory comparison of <i>δ</i><sup>13</sup>C and <i>δ</i>D measurements of atmospheric CH<sub>4</sub> for combined use of data sets from different laboratories