Geologic emissions of methane to the atmosphere

Etiope, Giuseppe; Klusman, Ronald W.

doi:10.1016/s0045-6535(02)00380-6

Cited by 290 publications

(214 citation statements)

References 62 publications

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“…Studies since 2000 have shown that the natural release to the Earth's surface of methane of geological origin is an important global greenhouse gas source (Etiope and Klusman, 2002;Kvenvolden and Rogers, 2005;Etiope et al, 2008;USEPA, 2010a;Etiope, 2012Etiope, , 2015. Indeed, the geological source is in the top-three natural methane sources after wetlands (and with freshwater systems) and about 10 % of total methane emissions, of the same magnitude or exceeding other sources or sinks, such as biomass burning, termites and soil uptake, considered in recent IPCC assessment reports .…”

Section: Onshore and Offshore Geological Sourcesmentioning

confidence: 99%

The global methane budget 2000–2012

Saunois

Bousquet

Poulter

et al. 2016

Earth Syst. Sci. Data

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947

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: Onshore and Offshore Geological Sourcesmentioning

confidence: 99%

The global methane budget 2000–2012

Saunois

Bousquet

Poulter

et al. 2016

Earth Syst. Sci. Data

Self Cite

947

733

View full text Add to dashboard Cite

show abstract

“…Geologic sources of methane have received much attention in recent years (Etiope and Klusman, 2002;Etiope and Milkov, 2004;Kvenvolden and Rogers, 2005), with reported global emissions ranging between 13 and 80 Tg CH 4 yr −1 (Judd, 2004;Etiope et al, 2008). Their representation in global models is complicated by the limited number of mud volcanoes for which the emissions have been quantified.…”

Section: A Priori Fluxesmentioning

confidence: 99%

A multi-year methane inversion using SCIAMACHY, accounting for systematic errors using TCCON measurements

et al. 2014

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Abstract. This study investigates the use of total column CH 4 (XCH 4 ) retrievals from the SCIAMACHY satellite instrument for quantifying large-scale emissions of methane. A unique data set from SCIAMACHY is available spanning almost a decade of measurements, covering a period when the global CH 4 growth rate showed a marked transition from stable to increasing mixing ratios. The TM5 4DVAR inverse modelling system has been used to infer CH 4 emissions from a combination of satellite and surface measurements for the period 2003-2010. In contrast to earlier inverse modelling studies, the SCIAMACHY retrievals have been corrected for systematic errors using the TCCON network of ground-based Fourier transform spectrometers. The aim is to further investigate the role of bias correction of satellite data in inversions. Methods for bias correction are discussed, and the sensitivity of the optimized emissions to alternative bias correction functions is quantified. It is found that the use of SCIAMACHY retrievals in TM5 4DVAR increases the estimated inter-annual variability of large-scale fluxes by 22 % compared with the use of only surface observations. The difference in global methane emissions between 2-year periods before and after July 2006 is estimated at 27-35 Tg yr −1 . The use of SCIAMACHY retrievals causes a shift in the emissions from the extra-tropics to the tropics of 50 ± 25 Tg yr −1 . The large uncertainty in this value arises from the uncertainty in the bias correction functions. Using measurements from the HIPPO and BARCA aircraft campaigns, we show that systematic errors in the SCIAMACHY measurements are a main factor limiting the performance of the inversions. To further constrain tropical emissions of methane using current and future satellite missions, extended validation capabilities in the tropics are of critical importance.Published by Copernicus Publications on behalf of the European Geosciences Union.

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“…Significant natural marine methane sources are mud volcanoes (Etiope and Klusman, 2002), hydrothermal systems (Schmale et al, 2012b), and 3 cold hydrocarbon seeps (Judd and Hovland, 2007). Due to global warming, flooded permafrost (Shakhova et al, 2010) and submarine Arctic gas hydrates (Berndt et al, 2014;Westbrook et al, 2009) are currently under debate as additional drivers for increasing marine methane emissions to the atmosphere.…”

Section: Introductionmentioning

confidence: 99%