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

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


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 languageEnglish (US)
Article numbereaao4842
JournalScience Advances
Issue number1
StatePublished - 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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