Arctic methane sources: Isotopic evidence for atmospheric inputs

Fisher, Rebecca E.; Sriskantharajah, S.; Lowry, David; Lanoisellé, M.; Fowler, C. M.; James, Rachael H.; Hermansen, Ove; Myhre, Cathrine Lund; Stohl, Andreas; Greinert, Jens; Nisbet‐Jones, P. B. R.; Mienert, Jürgen; Nisbet, E. G.

doi:10.1029/2011gl049319

Cited by 143 publications

(174 citation statements)

References 40 publications

Supporting

Mentioning

166

Contrasting

Order By: Relevance

“…Keeling plots of the d 13 C signature of atmospheric methane (Figure 9) indicate that the overall d 13 C-CH 4 signature of the methane sources to this area between 262 6 3& (2011) and 264 6 5& (2012). These values suggest that biogenic sources such as high-latitude wetlands, with d 13 C-CH 4 < 265& [Sriskantharajah et al, 2012], are the main source of atmospheric methane, but they do not preclude some (albeit small) contribution from seafloor methane seeps, which have d 13 C-CH 4 $255& [Fisher et al, 2011;Sahling et al, 2014].…”

Section: 1002/2015jc011084mentioning

confidence: 95%

“…Water was introduced to the equilibrator system on RV Heincke using the ship's underway pumped water system; the pump inlet was located 2.8 m below the sea surface. Air samples were collected as described in Fisher et al [2011], from the ship's bridge ($16 and 29 m above sea level for JR253 and MSM21/4, respectively) by directing a hose into the direction of incoming wind and pumping into 5 L Tedlar bags.…”

Section: Sample Collectionmentioning

confidence: 99%

See 1 more Smart Citation

Fluxes and fate of dissolved methane released at the seafloor at the landward limit of the gas hydrate stability zone offshore western Svalbard

et al. 2015

View full text Add to dashboard Cite

Widespread seepage of methane from seafloor sediments offshore Svalbard close to the landward limit of the gas hydrate stability zone (GHSZ) may, in part, be driven by hydrate destabilization due to bottom water warming. To assess whether this methane reaches the atmosphere where it may contribute to further warming, we have undertaken comprehensive surveys of methane in seawater and air on the upper slope and shelf region. Near the GHSZ limit at ∼400 m water depth, methane concentrations are highest close to the seabed, reaching 825 nM. A simple box model of dissolved methane removal from bottom waters by horizontal and vertical mixing and microbially mediated oxidation indicates that ∼60% of methane released at the seafloor is oxidized at depth before it mixes with overlying surface waters. Deep waters are therefore not a significant source of methane to intermediate and surface waters; rather, relatively high methane concentrations in these waters (up to 50 nM) are attributed to isopycnal turbulent mixing with shelf waters. On the shelf, extensive seafloor seepage at <100 m water depth produces methane concentrations of up to 615 nM. The diffusive flux of methane from sea to air in the vicinity of the landward limit of the GHSZ is ∼4–20 μmol m−2 d−1, which is small relative to other Arctic sources. In support of this, analyses of mole fractions and the carbon isotope signature of atmospheric methane above the seeps do not indicate a significant local contribution from the seafloor source.

show abstract

Section: 1002/2015jc011084mentioning

confidence: 95%

Section: Sample Collectionmentioning

confidence: 99%

Fluxes and fate of dissolved methane released at the seafloor at the landward limit of the gas hydrate stability zone offshore western Svalbard

et al. 2015

View full text Add to dashboard Cite

show abstract

“…For example, bubble plumes of CH 4 from the seabed have been observed in the water column but not detected in the Arctic atmosphere (Westbrook et al, 2009;Fisher et al, 2011). A large part of the seabed CH 4 production and emission is oxidized in the water column and does not reach the atmosphere (James et al, 2016).…”

Section: Oceanic Sourcesmentioning

confidence: 99%

“…Laser-based absorption spectrometers and isotope ratio mass spectrometry techniques have recently been developed to increase sampling frequency and allow in situ operation (McManus et al, 2010;Santoni et al, 2012). Measurements of δ 13 CH 4 can help to partition the different methanogenic processes of methane: biogenic (−70 to −55 ‰), thermogenic (−55 to −25 ‰) or pyrogenic (−25 to −15 ‰) sources (Quay et al, 1991;Miller et al, 2002;Fisher et al, 2011) or even the methanogenic pathway (McCalley et al, 2014). δD(CH 4 ) provides valuable information on the oxidation by the OH radicals due to a fractionation of about 300 ‰.…”

Section: Methane Isotope Observationsmentioning

confidence: 99%

The global methane budget 2000–2012

Saunois

Bousquet

Poulter

et al. 2016

Earth Syst. Sci. Data

948

733

View full text Add to dashboard Cite

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.

show abstract

“…This effect had not been recognized for more than a decade since the early years of GC-IRMS measurements (Merritt et al, 1995) and thus has not been taken into account in many data sets of atmospheric δ 13 C-CH 4 reported in the meantime (e.g. Miller et al, 2002;Morimoto et al, 2006;Fisher et al, 2011;Röckmann et al, 2011;Umezawa et al, 2012a, b). Furthermore, because the Kr effect is system dependent and variable with time , applying plausible corrections to past data may not be feasible.…”

Section: Krypton Interference In Gc-irmsmentioning

confidence: 99%

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

et al. 2018

View full text Add to dashboard Cite

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.

show abstract

Arctic methane sources: Isotopic evidence for atmospheric inputs

Cited by 143 publications

References 40 publications

Fluxes and fate of dissolved methane released at the seafloor at the landward limit of the gas hydrate stability zone offshore western Svalbard

Fluxes and fate of dissolved methane released at the seafloor at the landward limit of the gas hydrate stability zone offshore western Svalbard

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

Contact Info

Product

Resources

About

Arctic methane sources: Isotopic evidence for atmospheric inputs

Cited by 143 publications

References 40 publications

Fluxes and fate of dissolved methane released at the seafloor at the landward limit of the gas hydrate stability zone offshore western Svalbard

Fluxes and fate of dissolved methane released at the seafloor at the landward limit of the gas hydrate stability zone offshore western Svalbard

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

Contact Info

Product

Resources

About

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