How does rising atmospheric CO2 affect marine organisms?

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Dimethylsulfide, Global Warming and the Arctic Ocean
Qu, B. and Gabric, A.J. 2010. Using genetic algorithms to calibrate a dimethylsulfide production model in the Arctic Ocean. Chinese Journal of Oceanology and Limnology 28: 573-582.

The authors introduce their study by stating that "dimethylsulfide (DMS) is the main volatile sulfur [species] released during the formation and decay of microbial ocean biota," and that "aerosols formed from the atmospheric conversion of DMS to sulfate and methanesulfonic acid can exert a climate cooling effect directly by scattering and absorbing solar radiation and indirectly by promoting the formation of cloud condensation nuclei and increasing the albedo of clouds, thus reflecting more solar radiation back into space."

What was done
Working with climate and DMS production data from the region of the Barents Sea (70-80°N, 30-35°E) that were obtained over the period 1998 to 2002, Qu and Gabric employed a genetic algorithm to calibrate chlorophyll-a measurements (obtained from SeaWiFS satellite data) for use in a regional DMS production model. Then, using GCM temperature outputs for the periods of 1960-1970 (pre-industry CO2 level) and 2078-2086 (triple the pre-industry CO2 level), they calculated the warming-induced enhancement of the DMS flux from the Barents Sea region.

What was learned
The two researchers report that "significantly decreasing ice coverage, increasing sea surface temperature and decreasing mixed-layer depth could lead to annual DMS flux increases of more than 100% by the time of equivalent CO2 tripling (the year 2080)."

What it means
In commenting on their results, Qu and Gabric state that "such a large change would have a great impact on the Arctic energy budget and may offset the effects of anthropogenic warming that are amplified at polar latitudes." What is more, they say that "many of these physical changes will also promote similar perturbations for other biogenic species (Leck et al., 2004), some of which are now thought to be equally influential to the aerosol climate of the Arctic Ocean." Therefore, it can be appreciated that DMS production in a warming world -- especially when augmented by analogous biogenic phenomena -- may provide a truly huge moderating influence on the primary impetus for warming that is produced by mankind's emissions of CO2 and other trace greenhouse gases.

Leck, C., Tjernstrom, M., Matrai, P., Swietlicki, E. and Bigg, E.K. 2004. Can marine micro-organisms influence melting of the Arctic pack ice? EOS, Transactions, American Geophysical Union 85: 25-36.

Reviewed 6 October 2010