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Enhanced CO2 uptake at a shallow Arctic Ocean seep field overwhelms the positive warming potential of emitted methane.
- Source :
- Proceedings of the National Academy of Sciences of the United States of America; 5/23/2017, Vol. 114 Issue 21, p5355-5360, 6p
- Publication Year :
- 2017
-
Abstract
- Continued warming of the Arctic Ocean in coming decades is projected to trigger the release of teragrams (1 Tg = 10<superscript>6</superscript> tons) of methane from thawing subsea permafrost on shallow continental shelves and dissociation of methane hydrate on upper continental slopes. On the shallow shelves (<100 m water depth), methane released from the seafloor may reach the atmosphere and potentially amplify global warming. On the other hand, biological uptake of carbon dioxide (CO<subscript>2</subscript>) has the potential to offset the positive warming potential of emitted methane, a process that has not received detailed consideration for these settings. Continuous sea-air gas flux data collected over a shallow ebullitive methane seep field on the Svalbard margin reveal atmospheric CO<subscript>2</subscript> uptake rates (-33,300 ± 7,900 µmol m<superscript>-2</superscript>d<superscript>-1</superscript>) twice that of surrounding waters and ~1,900 times greater than the diffusive sea-air methane efflux (17.3 ± 4.8 µmol m<superscript>-2</superscript>d<superscript>-1</superscript>). The negative radiative forcing expected from this CO<subscript>2</subscript> uptake is up to 231 times greater than the positive radiative forcing from the methane emissions. Surface water characteristics (e.g., high dissolved oxygen, high pH, and enrichment of <superscript>13</superscript>C in CO<subscript>2</subscript>) indicate that upwelling of cold, nutrient-rich water from near the seafloor accompanies methane emissions and stimulates CO<subscript>2</subscript> consumption by photosynthesizing phytoplankton. These findings challenge the widely held perception that areas characterized by shallow-water methane seeps and/or strongly elevated sea-air methane flux always increase the global atmospheric greenhouse gas burden. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00278424
- Volume :
- 114
- Issue :
- 21
- Database :
- Complementary Index
- Journal :
- Proceedings of the National Academy of Sciences of the United States of America
- Publication Type :
- Academic Journal
- Accession number :
- 123264113
- Full Text :
- https://doi.org/10.1073/pnas.1618926114