Limited contribution of ancient methane to surface waters of the u.S. Beaufort sea shelf

Katy J. Sparrow; John D. Kessler; John R. Southon; Fenix Garcia-Tigreros; Kathryn M. Schreiner; Carolyn D. Ruppel; John B. Miller; Scott J. Lehman; Xiaomei Xu

doi:10.1126/sciadv.aao4842

Limited contribution of ancient methane to surface waters of the u.S. Beaufort sea shelf

Katy J. Sparrow, John D. Kessler, John R. Southon, Fenix Garcia-Tigreros, Kathryn M. Schreiner, Carolyn D. Ruppel, John B. Miller, Scott J. Lehman, Xiaomei Xu

Chemistry & Biochemistry

Research output: Contribution to journal › Article › peer-review

34 Scopus citations

Abstract

In response to warming climate, methane can be released to Arctic Ocean sediment and waters from thawing subsea permafrost and decomposing methane hydrates. However, it is unknown whether methane derived from this sediment storehouse of frozen ancient carbon reaches the atmosphere. We quantified the fraction of methane derived from ancient sources in shelf waters of the U.S. Beaufort Sea, a region that has both permafrost and methane hydrates and is experiencing significant warming. Although the radiocarbon-methane analyses indicate that ancient carbon is being mobilized and emitted as methane into shelf bottom waters, surprisingly, we find that methane in surface waters is principally derived from modern-aged carbon. We report that at and beyond approximately the 30-m isobath, ancient sources that dominate in deep waters contribute, at most, 10 ± 3% of the surface water methane. These results suggest that even if there is a heightened liberation of ancient carbon–sourced methane as climate change proceeds, oceanic oxidation and dispersion processes can strongly limit its emission to the atmosphere.

Original language	English (US)
Article number	eaao4842
Journal	Science Advances
Volume	4
Issue number	1
DOIs	https://doi.org/10.1126/sciadv.aao4842
State	Published - Jan 2018

Bibliographical note

Funding Information:
We thank B. Kopplin, M. Fleming, and A. Schwartz of the R/V Ukpik for providing skillful assistance of our science in Prudhoe Bay. We are grateful to M. Leonte for running GC-FID hydrocarbon concentration analyses in the Kessler laboratory. K.J.S. thanks A. Andersson of Stockholm University for fruitful discussions. Funding: The National Science Foundation (PLR-1417149; awarded to J.D.K.) primarily supported this work with additional support provided by the U.S. Department of Energy (DE-FE0028980; awarded to J.D.K.). Atmospheric 14C-CH4 measurements were funded by NASA via the Jet Propulsion Laboratory (Earth Ventures project “Carbon in Arctic Reservoirs Vulnerability Experiment”) to the University of Colorado under contract 1424124. K.M.S. acknowledges support from the University of Minnesota Grant-in-Aid program. Author contributions: K.J.S. and J.D.K. led

Publisher Copyright:
Copyright © 2018 The Authors.

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title = "Limited contribution of ancient methane to surface waters of the u.S. Beaufort sea shelf",

abstract = "In response to warming climate, methane can be released to Arctic Ocean sediment and waters from thawing subsea permafrost and decomposing methane hydrates. However, it is unknown whether methane derived from this sediment storehouse of frozen ancient carbon reaches the atmosphere. We quantified the fraction of methane derived from ancient sources in shelf waters of the U.S. Beaufort Sea, a region that has both permafrost and methane hydrates and is experiencing significant warming. Although the radiocarbon-methane analyses indicate that ancient carbon is being mobilized and emitted as methane into shelf bottom waters, surprisingly, we find that methane in surface waters is principally derived from modern-aged carbon. We report that at and beyond approximately the 30-m isobath, ancient sources that dominate in deep waters contribute, at most, 10 ± 3% of the surface water methane. These results suggest that even if there is a heightened liberation of ancient carbon–sourced methane as climate change proceeds, oceanic oxidation and dispersion processes can strongly limit its emission to the atmosphere.",

author = "Sparrow, {Katy J.} and Kessler, {John D.} and Southon, {John R.} and Fenix Garcia-Tigreros and Schreiner, {Kathryn M.} and Ruppel, {Carolyn D.} and Miller, {John B.} and Lehman, {Scott J.} and Xiaomei Xu",

note = "Funding Information: We thank B. Kopplin, M. Fleming, and A. Schwartz of the R/V Ukpik for providing skillful assistance of our science in Prudhoe Bay. We are grateful to M. Leonte for running GC-FID hydrocarbon concentration analyses in the Kessler laboratory. K.J.S. thanks A. Andersson of Stockholm University for fruitful discussions. Funding: The National Science Foundation (PLR-1417149; awarded to J.D.K.) primarily supported this work with additional support provided by the U.S. Department of Energy (DE-FE0028980; awarded to J.D.K.). Atmospheric 14C-CH4 measurements were funded by NASA via the Jet Propulsion Laboratory (Earth Ventures project “Carbon in Arctic Reservoirs Vulnerability Experiment”) to the University of Colorado under contract 1424124. K.M.S. acknowledges support from the University of Minnesota Grant-in-Aid program. Author contributions: K.J.S. and J.D.K. led Publisher Copyright: Copyright {\textcopyright} 2018 The Authors.",

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doi = "10.1126/sciadv.aao4842",

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AU - Kessler, John D.

AU - Southon, John R.

AU - Garcia-Tigreros, Fenix

AU - Schreiner, Kathryn M.

AU - Ruppel, Carolyn D.

AU - Miller, John B.

AU - Lehman, Scott J.

AU - Xu, Xiaomei

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N2 - In response to warming climate, methane can be released to Arctic Ocean sediment and waters from thawing subsea permafrost and decomposing methane hydrates. However, it is unknown whether methane derived from this sediment storehouse of frozen ancient carbon reaches the atmosphere. We quantified the fraction of methane derived from ancient sources in shelf waters of the U.S. Beaufort Sea, a region that has both permafrost and methane hydrates and is experiencing significant warming. Although the radiocarbon-methane analyses indicate that ancient carbon is being mobilized and emitted as methane into shelf bottom waters, surprisingly, we find that methane in surface waters is principally derived from modern-aged carbon. We report that at and beyond approximately the 30-m isobath, ancient sources that dominate in deep waters contribute, at most, 10 ± 3% of the surface water methane. These results suggest that even if there is a heightened liberation of ancient carbon–sourced methane as climate change proceeds, oceanic oxidation and dispersion processes can strongly limit its emission to the atmosphere.

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Limited contribution of ancient methane to surface waters of the u.S. Beaufort sea shelf

Abstract

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