The East Siberian Arctic Shelf: towards further assessment of permafrost-related methane fluxes and role of sea ice

Shakhova, Natalia; Semiletov, I. P.; Сергиенко, В. И.; Lobkovsky, L. I.; Yusupov, V. I.; Salyuk, A.; Salomatin, A.; Chernykh, D.; Kosmach, Denis; Panteleev, Gleb; Nicolsky, Dmitry; Samarkin, V.; Joye, Samantha B.; Charkin, Alexander; Dudarev, Oleg V.; Meluzov, A. А.; Gustafsson, Örjan

doi:10.1098/rsta.2014.0451

Cited by 156 publications

(231 citation statements)

References 38 publications

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“…Since then, oceanographic campaigns have been organized, especially to sample bubbling areas. For instance, Shakhova et al (2010Shakhova et al ( , 2014 infer 8-17 Tg CH 4 yr −1 emissions just for the East Siberian Arctic Shelf (ESAS), based on the extrapolation of numerous but local measurements, and possibly related to melting seabed permafrost (Shakhova et al, 2015). Because of the highly heterogeneous distribution of dissolved CH 4 in coastal regions, where bubbles can reach the atmosphere, extrapolation of in situ local measurements to the global scale can be hazardous and lead to biased global estimates.…”

Section: Oceanic Sourcesmentioning

confidence: 99%

The global methane budget 2000–2012

Saunois

Bousquet

Poulter

et al. 2016

Earth Syst. Sci. Data

945

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: Oceanic Sourcesmentioning

confidence: 99%

The global methane budget 2000–2012

Saunois

Bousquet

Poulter

et al. 2016

Earth Syst. Sci. Data

945

733

View full text Add to dashboard Cite

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“…Moreover, the first results from offshore drilling (accomplished from the fast ice in April 2011) down to 52 m below the sea floor in the southeastern Laptev Sea showed that the sediment core was entirely unfrozen, and 8-12 • C warmer than an on-land sediment core obtained in the nearby Chay-Tumus borehole (Shakhova et al, 2014), confirming these authors' modeling results. Besides, a major portion (> 80 %) of the Russian Arctic shelf is underlain by subsea permafrost; this permafrost has been degrading at increasing rates during the last 30 years, releasing organic carbon (OC) and pre-formed methane (CH 4 ) stored within and beneath subsea permafrost (Shakhova et al, 2017). Seafloor erosion could start from initial ground ice melt followed by formation of a polygonal form of seafloor landscape.…”

Section: Introductionmentioning

confidence: 99%

“…Some authors suggest that it would take ∼ 5-7 millennia for subsea permafrost to reach thaw point (Romanovskii et al, 2005), meaning that the coastal subsea permafrost is still stable. Others believe that in the coastal areas of the shallow Siberian Arctic seas, where permafrost was submerged most recently, taliks (layers or columns of thawed sediments within permafrost) might form as a result of the combined effect of geothermal flux from fault zones, the warming effect of rivers and overlying seawater, and the already present thermokarst Shakhova et al, 2009Shakhova et al, , 2015Nicolsky and Shakhova, 2010; Figure 1. A view of the Arctic hydrological cycle showing key links between land, ocean, and atmosphere (modified from http://arcticchamp.…”

Section: Introductionmentioning

confidence: 99%

“…According to Shakhova et al (2017), development of taliks of different origins could lead to formation of vertical erosion channels, helping gas fronts to propagate upwards towards the seafloor. These taliks could be identified by groundwater discharge that could be manifested as large, temporally and spatially variable point sources, which could have a significant impact on the hydrological and geochemical parameters of coastal waters.…”

Section: Introductionmentioning

confidence: 99%

“…Global warming has regional effects on the Arctic, including on all cryospheric features. Energy and water fluxes shape the regional temperature regime, which is a primary factor in determining the physical state (frozen vs. thawed), trace gas fluxes, rates of productivity, and the link to regional climate (Serreze et al, 2006;Vörösmarty et al, 2001;Shakhova et al, 2010Shakhova et al, , 2014Shakhova et al, , 2017Semiletov et al, 2007Semiletov et al, , 2016Vonk et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

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Discovery and characterization of submarine groundwater discharge in the Siberian Arctic seas: a case study in the Buor-Khaya Gulf, Laptev Sea

et al. 2017

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Abstract. It has been suggested that increasing terrestrial water discharge to the Arctic Ocean may partly occur as submarine groundwater discharge (SGD), yet there are no direct observations of this phenomenon in the Arctic shelf seas. This study tests the hypothesis that SGD does exist in the Siberian Arctic Shelf seas, but its dynamics may be largely controlled by complicated geocryological conditions such as permafrost. The field-observational approach in the southeastern Laptev Sea used a combination of hydrological (temperature, salinity), geological (bottom sediment drilling, geoelectric surveys), and geochemical ( 224 Ra, 223 Ra, 228 Ra, and 226 Ra) techniques. Active SGD was documented in the vicinity of the Lena River delta with two different operational modes. In the first system, groundwater discharges through tectonogenic permafrost talik zones was registered in both winter and summer. The second SGD mechanism was cryogenic squeezing out of brine and watersoluble salts detected on the periphery of ice hummocks in the winter. The proposed mechanisms of groundwater transport and discharge in the Arctic land-shelf system is elaborated. Through salinity vs. 224 Ra and 224 Ra/ 223 Ra diagrams, the three main SGD-influenced water masses were identified and their end-member composition was constrained. Based on simple mass-balance box models, discharge rates at sites in the submarine permafrost talik zone were 1.7×10 6 m 3 d −1 or 19.9 m 3 s −1 , which is much higher than the April discharge of the Yana River. Further studies should apply these techniques on a broader scale with the objective of elucidating the relative importance of the SGD transport vector relative to surface freshwater discharge for both water balance and aquatic components such as dissolved organic carbon, carbon dioxide, methane, and nutrients.

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Dynamic simulations of potential methane release from East Siberian continental slope sediments

Stranne

O’Regan

Dickens

et al. 2016

Geochem Geophys Geosyst

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Sediments deposited along continental margins of the Arctic Ocean presumably host large amounts of methane (CH 4 ) in gas hydrates. Here we apply numerical simulations to assess the potential of gas hydrate dissociation and methane release from the East Siberian slope over the next 100 years. Simulations are based on a hypothesized bottom water warming of 38C, and an assumed starting distribution of gas hydrate. The simulation results show that gas hydrate dissociation in these sediments is relatively slow, and that CH 4 fluxes toward the seafloor are limited by low sediment permeability. The latter is true even when sediment fractures are permitted to form in response to overpressure in pore space. With an initial gas hydrate distribution dictated by present-day pressure and temperature conditions, nominally 0.35 Gt of CH 4 are released from the East Siberian slope during the first 100 years of the simulation. However, this CH 4 discharge becomes significantly smaller ($0.05 Gt) if glacial sea level changes in the Arctic Ocean are considered. This is because a lower sea level during the last glacial maximum (LGM) must result in depleted gas hydrate abundance within the most sensitive region of the modern gas hydrate stability zone. Even if all released CH 4 reached the atmosphere, the amount coming from East Siberian slopes would be trivial compared to present-day atmospheric CH 4 inputs from other sources.

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The East Siberian Arctic Shelf: towards further assessment of permafrost-related methane fluxes and role of sea ice

Cited by 156 publications

References 38 publications

The global methane budget 2000–2012

The global methane budget 2000–2012

Discovery and characterization of submarine groundwater discharge in the Siberian Arctic seas: a case study in the Buor-Khaya Gulf, Laptev Sea

Dynamic simulations of potential methane release from East Siberian continental slope sediments

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