How does rising atmospheric CO2 affect marine organisms?

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The Little Ice Age in Antarctica: Conditions in the Ross Sea
Rhodes, R.H., Bertler, N.A.N., Baker, J.A., Steen-Larsen, H.C., Sneed, S.B., Morgenstern, U. and Johnsen, S.J. 2012. Little Ice Age climate and oceanic conditions of the Ross Sea, Antarctica from a coastal ice core record. Climate of the Past 8: 1223-1238.

The authors write that "increasing paleoclimatic evidence suggests that the Little Ice Age (LIA) was a global climate change event." But they say that "understanding the forcings and associated climate system feedbacks of the LIA is made difficult by the scarcity of Southern Hemisphere paleoclmate records."

What was done
Hoping to reduce this scarcity, Rhodes et al. used "a new glaciochemical record of a coastal ice core from Mt Erebus Saddle, Antarctica, to reconstruct atmospheric and oceanic conditions in the Ross Sea sector of Antarctica over the past five centuries," wherein they observed that "the LIA is identified in stable isotope (δD) and lithophile element records."

What was learned
The seven scientists report that the first of these data sets suggests that "the region experienced 1.6 1.4°C cooler average temperatures prior to 1850 AD than during the last 150 years." In addition, they say that the second data set suggests "strong (>57 m/s) prevailing katabatic winds between 1500 and 1800 AD," with three especially strong wind periods centered on about 1690, 1770 and 1840 AD. And they indicate that "these strong wind events occur coincidently with cooler temperatures." Last of all, they state that "ice core concentrations of the biogenic sulphur species MS- suggest that biological productivity in the Ross Sea polynya was ~80% higher prior to1875 AD than at any subsequent time."

What it means
In the closing words of the authors, "we conclude that during the LIA colder temperatures promoted stronger katabatic winds across the Ross Ice Shelf, causing sea ice divergence and creating a greater polynya area in the Ross Sea," which allowed for the increased marine primary productivity experienced there between 1600 and 1875 AD. And we would only add to their statement that these findings help to substantiate the fact that the LIA was indeed a global climatic event.

Reviewed 13 February 2013