How does rising atmospheric CO2 affect marine organisms?

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Emerging Carbon Sinks of Antarctica
Peck, L.S., Barnes, D.K.A., Cook, A.J., Fleming, A.H. and Clarke, A. 2010. Negative feedback in the cold: ice retreat produces new carbon sinks in Antarctica. Global Change Biology 16: 2614-2623.

The authors write that the loss of glaciers and ice shelves is often thought of as something that "will predominantly increase warming of the earth because of changes in albedo and heat uptake by newly uncovered ground and ocean," but they say that an important opposing effect of this phenomenon "is the opening up of new areas for biological productivity."

What was done
Working with the database of Cook et al. (2005) that contains a detailed centennial history of change in all coastal ice fronts associated with the Antarctic Peninsula -- which was compiled from historical accounts, aerial photographs and satellite imagery -- Peck et al. developed a systematic time series of changes in the surface ice/water boundary surrounding the Antarctic Peninsula since the early 20th century. And complementing this information with a 10-year time-series of chlorophyll depth profiles (1997-2007) obtained from a near-shore location in northern Marguerite Bay that was developed by Clarke et al. (2008), they reconstructed the magnitude of new oceanic production that developed around the Antarctic Peninsula as sea ice progressively gave way to ever more open water.

What was learned
The five researchers with the British Antarctic Survey report that as the ice cover along the Antarctic Peninsula has retreated over the last 50 years, "more than 0.5 Mtonnes of carbon has been incorporated into biological standing stock that was not there previously, 3.5 Mtonnes is fixed by phytoplankton blooms and 0.7 Mtonnes deposited to the seabed." With respect to the future, they say that if only 15% of the remaining ice covered areas act in the same way, "over 50 Mtonnes of new carbon would be fixed annually and around 10 Mtonnes of this deposited to the seabed in coastal or adjacent areas," while "over 9 Mtonnes of carbon would be locked up in biological communities in the water column or on the sea bed." And over tens to hundreds of thousands of years, they suggest that "this process may act as a climate control mechanism."

What it means
Life plays a major role in determining the climate of the planet, and has for eons been able to maintain the globe's mean temperature within a range conducive to its continued existence. Peck et al. have illuminated one of the many phenomena that contribute to this grand homeostasis.

Clarke, A., Meredith, M.P., Wallace, M.I., Brandon, M.A. and Thomas, D.N. 2008. Seasonal and interannual variability in temperature, chlorophyll and macronutrients in northern Maguerite Bay, Antarctica. Deep Sea Research Part II 55: 1988-2006.

Cook, A.J., Fox, A.J., Vaughan, D.G. and Ferrigno, J.G. 2005. Retreating glacier fronts on the Antarctic Peninsula over the past half-century. Science 308: 541-544.

Reviewed 8 December 2010