Abundant pre-industrial carbon detected in Canadian Arctic headwaters: implications for the permafrost carbon feedback

Dean, Joshua; Velde, Ype van der; Garnett, Mark H.; Dinsmore, Kerry J.; Baxter, Robert C.; Lessels, J. S.; Smith, Pete; Street, Lorna E.; Subke, Jens‐Arne; Tetzlaff, Doerthe; Washbourne, Ian; Wookey, Philip A.; Billett, Michael F.

doi:10.1088/1748-9326/aaa1fe

Cited by 31 publications

(61 citation statements)

References 46 publications

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“…This C is increasingly vulnerable to destabilization and release due to permafrost thaw driven by rising Arctic air temperatures [2][3][4] . Inland waters in stable permafrost landscapes primarily receive terrestrial C from contemporary biological turnover within seasonally thawed topsoils [5][6][7] . As these landscapes warm, it is likely more contemporary C will be released to inland waters from sustained and enhanced biological turnover and event-based vegetation die-off (Arctic greening versus browning) 8,9 .…”

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East Siberian Arctic inland waters emit mostly contemporary carbon

et al. 2020

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Inland waters (rivers, lakes and ponds) are important conduits for the emission of terrestrial carbon in Arctic permafrost landscapes. These emissions are driven by turnover of contemporary terrestrial carbon and additional pre-aged (Holocene and late-Pleistocene) carbon released from thawing permafrost soils, but the magnitude of these source contributions to total inland water carbon fluxes remains unknown. Here we present unique simultaneous radiocarbon age measurements of inland water CO 2 , CH 4 and dissolved and particulate organic carbon in northeast Siberia during summer. We show that >80% of total inland water carbon was contemporary in age, but pre-aged carbon contributed >50% at sites strongly affected by permafrost thaw. CO 2 and CH 4 were younger than dissolved and particulate organic carbon, suggesting emissions were primarily fuelled by contemporary carbon decomposition. Our findings reveal that inland water carbon emissions from permafrost landscapes may be more sensitive to changes in contemporary carbon turnover than the release of pre-aged carbon from thawing permafrost.

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East Siberian Arctic inland waters emit mostly contemporary carbon

et al. 2020

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“…An effective identifier of old C (i.e., C sequestered in organic matter prior to 1955) is radiocarbon (Dean et al, ). This has been applied to permafrost C stores that are converted to CH 4 and other forms of mobile C (Dean et al, ; Hilton et al, ; Raymond et al, ; Schell, ; Schuur et al, ; Walter Anthony et al, ). A recent study applied this method to estimate a direct permafrost CH 4 climate feedback of 0.1 to 0.3 Pg C via ebullition from thermokarst lake expansion in the Alaskan and Siberian yedoma region over the past 60 years (Walter Anthony et al, ).…”

Section: Permafrostmentioning

confidence: 99%

Methane Feedbacks to the Global Climate System in a Warmer World

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et al. 2018

Reviews of Geophysics

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Methane (CH4) is produced in many natural systems that are vulnerable to change under a warming climate, yet current CH4 budgets, as well as future shifts in CH4 emissions, have high uncertainties. Climate change has the potential to increase CH4 emissions from critical systems such as wetlands, marine and freshwater systems, permafrost, and methane hydrates, through shifts in temperature, hydrology, vegetation, landscape disturbance, and sea level rise. Increased CH4 emissions from these systems would in turn induce further climate change, resulting in a positive climate feedback. Here we synthesize biological, geochemical, and physically focused CH4 climate feedback literature, bringing together the key findings of these disciplines. We discuss environment‐specific feedback processes, including the microbial, physical, and geochemical interlinkages and the timescales on which they operate, and present the current state of knowledge of CH4 climate feedbacks in the immediate and distant future. The important linkages between microbial activity and climate warming are discussed with the aim to better constrain the sensitivity of the CH4 cycle to future climate predictions. We determine that wetlands will form the majority of the CH4 climate feedback up to 2100. Beyond this timescale, CH4 emissions from marine and freshwater systems and permafrost environments could become more important. Significant CH4 emissions to the atmosphere from the dissociation of methane hydrates are not expected in the near future. Our key findings highlight the importance of quantifying whether CH4 consumption can counterbalance CH4 production under future climate scenarios.

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“… 14 C values for dissolved organic carbon exported from peatland catchments that have been heavily disturbed (e.g., by drainage; Moore et al, ), semidisturbed (e.g., by long‐term impacts from minor human activity; Billett et al, ), or relatively undisturbed by human activity (Aiken et al, ; Dean, van der Velde, et al, ; Campeau et al, ; Hulatt, Kaartokallio, Oinonen, et al, ; Hulatt, Kaartokallio, Asmala, et al, ; Ledesma et al, ; Leith et al, ; Marwick et al, ; Müller et al, ; Stimson et al, , ). Modern DO 14 C values plot above the dotted line; the number of modern values for each catchment type is shown in blue, and the number of values older than modern is shown in red (total n = 209; see supporting information for data sources).…”

Section: Introductionmentioning

confidence: 99%

The Potential Hidden Age of Dissolved Organic Carbon Exported by Peatland Streams

et al. 2019

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Radiocarbon ( 14 C) is a key tracer for detecting the mobilization of previously stored terrestrial organic carbon (C) into aquatic systems. Old C (>1,000 years BP) may be "masked" by postbomb C (fixed from the atmosphere post-1950 CE), potentially rendering bulk aquatic dissolved organic C (DOC) 14 C measurements insensitive to old C. We collected DOC with a modern 14 C signature from a temperate Scottish peatland stream and decomposed it to produce CO 2 under simulated natural conditions over 140 days. We measured the 14 C of both DOC and CO 2 at seven time points and found that while DOC remained close to modern in age, the resultant CO 2 progressively increased in age up to 2,356 ± 767 years BP. The results of this experiment demonstrate that the bulk DO 14 C pool can hide the presence of old C within peatland stream DOC export, demonstrating that bulk DO 14 C measurements can be an insensitive indicator of peatland disturbance. Our experiment also demonstrates that this old C component is biologically and photochemically available for conversion to the greenhouse gas CO 2 , and as such, bulk DO 14 C measurements do not reflect the 14 C signature of the labile organic C pool exported by inland water systems more broadly. Moreover, our experiment suggests that old C may be an important component of CO 2 emissions to the atmosphere from peatland aquatic systems, with implications for tracing and modeling interactions between the hydrological and terrestrial C cycles.

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Abundant pre-industrial carbon detected in Canadian Arctic headwaters: implications for the permafrost carbon feedback

Cited by 31 publications

References 46 publications

East Siberian Arctic inland waters emit mostly contemporary carbon

East Siberian Arctic inland waters emit mostly contemporary carbon

Methane Feedbacks to the Global Climate System in a Warmer World

The Potential Hidden Age of Dissolved Organic Carbon Exported by Peatland Streams

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