Reduced methane growth rate explained by decreased Northern Hemisphere microbial sources

Kai, Fuu Ming; Tyler, S. C.; Randerson, James T.; Blake, Donald R.

doi:10.1038/nature10259

Cited by 183 publications

(162 citation statements)

References 28 publications

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“…For instance, methane emissions from rice paddies increase with organic amendments (Cai et al, 1997) but can be mitigated by applying other types of fertilizers (mineral, composts, biogas residues, wet seeding) (Wassmann et al, 2000). Some studies have suggested that decreases in microbial emissions, particularly due to changes in the practice of rice cultivation, could be responsible for a ∼ 15 Tg CH 4 yr −1 decrease over the period from 1980s to 2000s (Kai et al, 2011).…”

Section: Rice Cultivationmentioning

confidence: 99%

“…the use of urea and organic fertilizers), soil temperature, soil type (texture and aggregated size), rice variety and cultivation practices (e.g. tillage, seeding, and weeding practices) (USEPA, 2011(USEPA, , 2016Kai et al, 2011;Yan et al, 2009;Conrad et al, 2000). For instance, methane emissions from rice paddies increase with organic amendments (Cai et al, 1997) but can be mitigated by applying other types of fertilizers (mineral, composts, biogas residues, wet seeding) (Wassmann et al, 2000).…”

Section: Rice Cultivationmentioning

confidence: 99%

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The global methane budget 2000–2012

Saunois

Bousquet

Poulter

et al. 2016

Earth Syst. Sci. Data

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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: Rice Cultivationmentioning

confidence: 99%

Section: Rice Cultivationmentioning

confidence: 99%

The global methane budget 2000–2012

Saunois

Bousquet

Poulter

et al. 2016

Earth Syst. Sci. Data

Self Cite

947

733

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“…The University of California Irvine (UCI) measured atmospheric δ 13 C-CH 4 by offline DI-IRMS and δD-CH 4 by GC-IRMS (Tyler et al, 1999(Tyler et al, , 2007Kai et al, 2011). The UCI GC-IRMS system for both δ 13 C-CH 4 and δD-CH 4 has been described in detail by Rice et al (2001).…”

Section: Ucimentioning

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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“…Over the past several decades, the atmospheric CH 4 growth rate has varied considerably, with changes in fossil fuel emissions (Khalil and Shearer, 2000;Bousquet et al, 2006), atmospheric sinks (Dentener et al, 2003;Karlsdottir and Isaksen, 2000), and fertilizer and W. J. Riley et al: Barriers to predicting changes in global terrestrial methane fluxes irrigation management in rice agriculture (Kai et al, 2010) proposed as explanations.…”

Section: Introductionmentioning

confidence: 99%

Barriers to predicting changes in global terrestrial methane fluxes: analyses using CLM4Me, a methane biogeochemistry model integrated in CESM

et al. 2011

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Abstract. Terrestrial net CH 4 surface fluxes often represent the difference between much larger gross production and consumption fluxes and depend on multiple physical, biological, and chemical mechanisms that are poorly understood and represented in regional-and global-scale biogeochemical models. To characterize uncertainties, study feedbacks between CH 4 fluxes and climate, and to guide future model development and experimentation, we developed and tested a new CH 4 biogeochemistry model (CLM4Me) integrated in the land component (Community Land Model; CLM4) of the Community Earth System Model (CESM1). CLM4Me includes representations of CH 4 production, oxidation, aerenchyma transport, ebullition, aqueous and gaseous diffusion, and fractional inundation. As with most global models, CLM4 lacks important features for predicting current and future CH 4 fluxes, including: vertical representation of soil organic matter, accurate subgrid scale hydrology, realistic representation of inundated system vegetation, anaerobic decomposition, thermokarst dynamics, and aqueous chemistry. We compared the seasonality and magnitude of predicted CH 4 emissions to observations from 18 sites and three global atmospheric inversions. Simulated net CH 4 emissions using our baseline parameter set were 270, 160, 50, and 70 Tg CH 4 yr −1 globally, in the tropics, in the temperate zone, and north of 45 • N, respectively; these values are within the range of previous estimates. We then used the model to characterize the sensitivity of regional and global CH 4 emission estimates to uncertainties in model paCorrespondence to: W. J. Riley (wjriley@lbl.gov) rameterizations. Of the parameters we tested, the temperature sensitivity of CH 4 production, oxidation parameters, and aerenchyma properties had the largest impacts on net CH 4 emissions, up to a factor of 4 and 10 at the regional and gridcell scales, respectively. In spite of these uncertainties, we were able to demonstrate that emissions from dissolved CH 4 in the transpiration stream are small (<1 Tg CH 4 yr −1 ) and that uncertainty in CH 4 emissions from anoxic microsite production is significant. In a 21st century scenario, we found that predicted declines in high-latitude inundation may limit increases in high-latitude CH 4 emissions. Due to the high level of remaining uncertainty, we outline observations and experiments that would facilitate improvement of regional and global CH 4 biogeochemical models.

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Reduced methane growth rate explained by decreased Northern Hemisphere microbial sources

Cited by 183 publications

References 28 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

Barriers to predicting changes in global terrestrial methane fluxes: analyses using CLM4Me, a methane biogeochemistry model integrated in CESM

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Reduced methane growth rate explained by decreased Northern Hemisphere microbial sources

Cited by 183 publications

References 28 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

Barriers to predicting changes in global terrestrial methane fluxes: analyses using CLM4Me, a methane biogeochemistry model integrated in CESM

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Product

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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