Sunday, January 11, 2009

Sea Rise Over Continental Shelves Significantly Affected Past Global Carbon Cycle

Since the Last Glacial Maximum (LGM; about 21,000 years ago) sea level has risen by 130 meters (430 feet), resulting in continental shelf submergence and a massive expansion of the surface area of shelf seas.
Although shelf seas only account for 7 percent of the oceanic surface area, recent observations demonstrate that they host significant fluxes of carbon dioxide (CO2) between the ocean and atmosphere.
Further, dissolved and particulate carbon are thought to be transported from shelf areas into sinks in the deep ocean through a mechanism called the "continental shelf pump." Through reconstructions of shelf geography stretching to the LGM, Rippeth et al. analyze the effect of sea level rise and consequent flooding of continental shelves on the growth of the continental shelf pump.
Combining these reconstructions with contemporary estimates of carbon flux between the ocean and atmosphere allows the authors to conclude that expanding shelf seas have significantly influenced the global carbon cycle via the continental shelf pump, with weaker pumping during times when shallower shelf seas were present.
Journal reference:
Tom P. Rippeth et al. Impact of sea-level rise over the last deglacial transition on the strength of the continental shelf CO2 pump. Geophysical Research Letters, DOI: 10.1029/2008GL035880
Adapted from materials provided by American Geophysical Union, via EurekAlert!, a service of AAAS.

No comments: