Enhanced CO2 uptake at a shallow Arctic Ocean seep field overwhelms the positive warming potential of emitted methane

• Published in: Proceedings of the National Academy of Sciences
• Main Authors: Pohlman, John W., Greinert, Jens, Ruppel, Carolyn, Silyakova, Anna, Vielstädte, Lisa, Casso, Michael, Mienert, Jürgen, Bünz, Stefan
• Format: Text
• Language: English
• Published: National Academy of Sciences 2017
• Subjects: Physical Sciences; Arctic; Arctic Ocean; Global warming
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5448205/; http://www.ncbi.nlm.nih.gov/pubmed/28484018; https://doi.org/10.1073/pnas.1618926114

Methane released from the seafloor and transported to the atmosphere has the potential to amplify global warming. At an arctic site characterized by high methane flux from the seafloor, we measured methane and carbon dioxide (CO2) exchange across the sea−air interface. We found that CO2 uptake in an area of elevated methane efflux was enhanced relative to surrounding waters, such that the negative radiative forcing effect (cooling) resulting from CO2 uptake overwhelmed the positive radiative forcing effect (warming) supported by methane output. Our work suggests physical mechanisms (e.g., upwelling) that transport methane to the surface may also transport nutrient-enriched water that supports enhanced primary production and CO2 drawdown. These areas of methane seepage may be net greenhouse gas sinks.