How does rising atmospheric CO2 affect marine organisms?

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Modelling Southern Ocean Climate
Bodas-Salcedo, A., Williams, K.D., Ringer, M.A., Beau, I., Cole, J.N.S., Dufresne, J.-L., Koshiro, T., Stevens, B., Wang, Z. and Yokohata, T. 2014. Origins of the solar radiation biases over the Southern Ocean in CFMIP2 models. Journal of Climate 27: 41-56.

The authors write that "the Southern Ocean plays an important role in the earth's climate," as it is "a region of upwelling of intermediate waters and also of formation of deep waters farther south, connecting the ocean interior with the surface (e.g., Marshall and Speer, 2012)," which facts, as they continue, make it "an important part of the meridional overturning circulation." And as "one of the few areas where the deep ocean is connected to the surface," they say "it also plays a key role in CO2 and heat uptake (Calderia and Duffy, 2000; Kuhlbrodt and Gregory, 2012)," while noting that "details of the circulation in the Southern Ocean play a crucial role in determining the evolution of the Antarctic ice sheets and sea level," citing Holland et al. (2010) and Bouttes et al. (2012).

What was done
In an attempt to promote progress in modelling these important aspects of earth's climate system, Bodas-Salcedo et al. "studied the role of clouds in the Southern Ocean's solar radiation budget in the atmosphere-only simulations of the Cloud Feedback Model Intercomparison Project phase 2 (CFMIP2)," noting that the clouds of this region "may have a leading role in controlling the solar radiation that is absorbed by the climate system in those latitudes."

What was learned
The international team of ten researchers from six different countries concluded from their several analyses that the midlevel cloud regime "is the main contributor to reflected shortwave radiation biases." And, therefore, they suggest that "improving the simulation of these cloud types should help reduce the biases in the simulation of the solar radiation budget in the Southern Ocean in climate models."

What it means
The final conclusions of Bodas-Salcedo et al. are that (1) future work should "focus on quantifying the role of these clouds in the radiation budget over the Southern Ocean," and that (2) "this should help elucidate the relative contribution of these situations to the solar radiation budget over the Southern Ocean." And these statements clearly indicate that we are still not at the point where we have an acceptable working model of the Southern Ocean that adequately portrays its impact on earth's global climate.

Bouttes, N., Gregory, J.M., Kuhlbrodt, T. and Suzuki, T. 2012. The effect of wind-stress change on future sea level change in the Southern Ocean. Geophysical Research Letters 39: 10.1029/2012GL054207.

Caldeira, K. and Duffy, P.B. 2000. The role of the Southern Ocean in uptake and storage of anthropogenic carbon dioxide. Science 287: 620-622.

Holland, P.R., Jenkins, A. and Holland, D.M. 2010. Ice and ocean processes in the Bellingshausen Sea, Antarctica. Journal of Geophysical Research 115: 10.1029/2008JC005219.

Kuhlbrodt, T. and Gregory, J.M. 2012. Ocean heat uptake and its consequences for the magnitude of sea level rise and climate change. Geophysical Research Letters 39: 10.1029/2012GL052952.

Marshall, J. and Speer, K. 2012. Closure of the meridional overturning circulation through Southern Ocean upwelling. Nature Geoscience 5: 171-180.

Reviewed 26 March 2014