Factors controlling large scale variations in methane emissions from wetlands

Christensen, Torben R.; Ekberg, Anna; Ström, Lena; Mastepanov, Mikhail; Panikov, N. S.; Öquist, Mats; Svensson, Bo; Nykänen, Hannu; Martikainen, Pertti J.; Óskarsson, Hlynur

doi:10.1029/2002gl016848

Cited by 353 publications

(322 citation statements)

References 33 publications

(42 reference statements)

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“…This is probably due to the important role of precipitation for the wetland emissions in southern Europe, while for temperate and boreal regions the seasonal variation of wetland emissions is mainly driven by temperature (e.g. Christensen et al, 2003;Hodson et al, 2011). In contrast to the discussed four models, NAME derives much smaller seasonal variations, and for western Europe, eastern Europe, and EU-28 with the opposite phase (small maximum in winter).…”

Section: European Ch 4 Emissionsmentioning

confidence: 75%

Inverse modelling of European CH4 emissions during 2006–2012 using different inverse models and reassessed atmospheric observations

et al. 2018

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Abstract. We present inverse modelling (top down) estimates of European methane (CH 4 The hypothesis of significant natural emissions is supported by the finding that several inverse models yield significant seasonal cycles of derived CH 4 emissions with maxima in summer, while anthropogenic CH 4 emissions are assumed to have much lower seasonal variability. Taking into account the wetland emissions from the WETCHIMP ensemble, the top-down estimates are broadly consistent with the sum of anthropogenic and natural bottom-up inventories. However, the contribution of natural sources and their regional distribution remain rather uncertain.Furthermore, we investigate potential biases in the inverse models by comparison with regular aircraft profiles at four European sites and with vertical profiles obtained during the Infrastructure for Measurement of the European Carbon Cycle (IMECC) aircraft campaign. We present a novel approach to estimate the biases in the derived emissions, based on the comparison of simulated and measured enhancements of CH 4 compared to the background, integrated over the entire boundary layer and over the lower troposphere. The estimated average regional biases range between −40 and 20 % at the aircraft profile sites in France, Hungary and Poland.

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Section: European Ch 4 Emissionsmentioning

confidence: 75%

Inverse modelling of European CH4 emissions during 2006–2012 using different inverse models and reassessed atmospheric observations

et al. 2018

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“…Root exudates lead to an increase in substrate availability in the form of easily decomposable organic compounds, which can be used by methanogens to produce CH 4 (Aulakh et al, 2001;Christensen et al, 2003). There are studies that found positive correlations between radiation or net ecosystem production and CH 4 flux (Whiting and Chanton, 1993;Joabsson and Christensen, 2001), although there are also studies that found the opposite (Mikkelä et al, 1995;Ström et al, 2005).…”

Section: Effect Of Other Environmental Factors On Chmentioning

confidence: 96%

The role of Phragmites in the CH4 and CO2 fluxes in a minerotrophic peatland in southwest Germany

et al. 2016

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Abstract. Peatlands are interesting as a carbon storage option, but are also natural emitters of the greenhouse gas methane (CH 4 ). Phragmites peatlands are particularly interesting due to the global abundance of this wetland plant (Phragmites australis) and the highly efficient internal gas transport mechanism, which is called humidity-induced convection (HIC). The research aims were to (1) clarify how this plant-mediated gas transport influences the CH 4 fluxes, (2) which other environmental variables influence the CO 2 and CH 4 fluxes, and (3) whether Phragmites peatlands are a net source or sink of greenhouse gases. CO 2 and CH 4 fluxes were measured with the eddy covariance technique within a Phragmites-dominated fen in southwest Germany. One year of flux data (March 2013-February 2014 shows very clear diurnal and seasonal patterns for both CO 2 and CH 4 . The diurnal pattern of CH 4 fluxes was only visible when living, green reed was present. In August the diurnal cycle of CH 4 was the most distinct, with 11 times higher midday fluxes (15.7 mg CH 4 m −2 h −1 ) than night fluxes (1.41 mg CH 4 m −2 h −1 ). This diurnal cycle has the highest correlation with global radiation, which suggests a high influence of the plants on the CH 4 flux. But if the cause were the HIC, it would be expected that relative humidity would correlate stronger with CH 4 flux. Therefore, we conclude that in addition to HIC, at least one additional mechanism must be involved in the creation of the convective flow within the Phragmites plants. Overall, the fen was a sink for carbon and greenhouse gases in the measured year, with a total carbon uptake of 221 g C m −2 yr −1 (26 % of the total assimilated carbon). The net uptake of greenhouse gases was 52 g CO 2 eq. m −2 yr −1 , which is obtained from an uptake of CO 2 of 894 g CO 2 eq. m −2 yr −1 and a release of CH 4 of 842 g CO 2 eq. m −2 yr −1 .

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“…Globally, wetlands are the largest natural source of CH 4 emissions to the atmosphere (IPCC, 2013). Because wetland CH 4 emissions are highly sensitive to soil temperature and moisture conditions (Saarnio et al, 1997;Friborg et al, 2003;Christensen et al, 2003;Moore et al, 2011;Glagolev et al, 2011;Sabrekov et al, 2014), there is concern that they will provide positive feedback to future climate warming (Gedney et al, 2004;Eliseev et al, 2008;Ringeval et al, 2011). This risk is particularly important in the world's high latitudes because they contain nearly half of the world's wetlands (Lehner and Döll, 2004) and because the high latitudes have been and are forecast to continue experiencing more rapid warming than elsewhere (Serreze et al, 2000;IPCC, 2013).…”

Section: Introductionmentioning

confidence: 99%

WETCHIMP-WSL: intercomparison of wetland methane emissions models over West Siberia

et al. 2015

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Abstract. Wetlands are the world's largest natural source of methane, a powerful greenhouse gas. The strong sensitivity of methane emissions to environmental factors such as soil temperature and moisture has led to concerns about potential positive feedbacks to climate change. This risk is particularly relevant at high latitudes, which have experienced pronounced warming and where thawing permafrost could potentially liberate large amounts of labile carbon over the next 100 years. However, global models disagree as to the magnitude and spatial distribution of emissions, due to uncertainties in wetland area and emissions per unit area and a scarcity of in situ observations. Recent intensive field campaigns across the West Siberian Lowland (WSL) make this an ideal region over which to assess the perPublished by Copernicus Publications on behalf of the European Geosciences Union. T. J. Bohn et al.: Intercomparison of wetland methane emissions modelsformance of large-scale process-based wetland models in a high-latitude environment. Here we present the results of a follow-up to the Wetland and Wetland CH 4 Intercomparison of Models Project (WETCHIMP), focused on the West Siberian Lowland (WETCHIMP-WSL). We assessed 21 models and 5 inversions over this domain in terms of total CH 4 emissions, simulated wetland areas, and CH 4 fluxes per unit wetland area and compared these results to an intensive in situ CH 4 flux data set, several wetland maps, and two satellite surface water products. We found that (a) despite the large scatter of individual estimates, 12-year mean estimates of annual total emissions over the WSL from forward models (5.34 ± 0.54 Tg CH 4 yr −1 ), inversions (6.06 ± 1.22 Tg CH 4 yr −1 ), and in situ observations (3.91 ± 1.29 Tg CH 4 yr −1 ) largely agreed; (b) forward models using surface water products alone to estimate wetland areas suffered from severe biases in CH 4 emissions; (c) the interannual time series of models that lacked either soil thermal physics appropriate to the high latitudes or realistic emissions from unsaturated peatlands tended to be dominated by a single environmental driver (inundation or air temperature), unlike those of inversions and more sophisticated forward models; (d) differences in biogeochemical schemes across models had relatively smaller influence over performance; and (e) multiyear or multidecade observational records are crucial for evaluating models' responses to long-term climate change.

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Factors controlling large scale variations in methane emissions from wetlands

Cited by 353 publications

References 33 publications

Inverse modelling of European CH<sub>4</sub> emissions during 2006–2012 using different inverse models and reassessed atmospheric observations

Inverse modelling of European CH<sub>4</sub> emissions during 2006–2012 using different inverse models and reassessed atmospheric observations

The role of <i>Phragmites</i> in the CH<sub>4</sub> and CO<sub>2</sub> fluxes in a minerotrophic peatland in southwest Germany

WETCHIMP-WSL: intercomparison of wetland methane emissions models over West Siberia

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Factors controlling large scale variations in methane emissions from wetlands

Cited by 353 publications

References 33 publications

Inverse modelling of European CH&lt;sub&gt;4&lt;/sub&gt; emissions during 2006–2012 using different inverse models and reassessed atmospheric observations

Inverse modelling of European CH&lt;sub&gt;4&lt;/sub&gt; emissions during 2006–2012 using different inverse models and reassessed atmospheric observations

The role of &lt;i&gt;Phragmites&lt;/i&gt; in the CH&lt;sub&gt;4&lt;/sub&gt; and CO&lt;sub&gt;2&lt;/sub&gt; fluxes in a minerotrophic peatland in southwest Germany

WETCHIMP-WSL: intercomparison of wetland methane emissions models over West Siberia

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Inverse modelling of European CH<sub>4</sub> emissions during 2006–2012 using different inverse models and reassessed atmospheric observations

Inverse modelling of European CH<sub>4</sub> emissions during 2006–2012 using different inverse models and reassessed atmospheric observations

The role of <i>Phragmites</i> in the CH<sub>4</sub> and CO<sub>2</sub> fluxes in a minerotrophic peatland in southwest Germany