How does rising atmospheric CO2 affect marine organisms?

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Changes in Coccolith Calcification in Stable Ocean CO2 Conditions
Berger, C., Meier, K.J.S., Kinkel, H. and Baumann, K.-H. 2014. Changes in calcification of coccoliths under stable atmospheric CO2. Biogeosciences 11: 929-944.

The authors write that "the response of coccolithophore calcification to ocean acidification has been studied in culture experiments as well as in present and past oceans," noting that responses have varied among different species and strains. They also report that "for the relatively small carbonate chemistry changes observed in natural environments, a uniform response of the entire coccolithophore community has not been documented." In addition, they say that "previous palaeo-studies basically focus on changes in coccolith weight due to increasing CO2 and the resulting changes in the carbonate system," while only a few studies "focus on the influence of other environmental factors."

What was done
Working with the coccolith family Noelaerhabdaceae - which constitutes the majority of the coccolith assemblage inhabiting the North Atlantic Ocean - Berger et al. analyzed average coccolith weights obtained from three Holocene sediment cores extracted along a north-south North Atlantic transect.

What was learned
The four researchers documented the occurrence of "weight changes during the Holocene of the same amplitude as previously reported for the CO2 increase of the last glacial to interglacial change, but with opposing trends in different regions." And in this regard, they suggest that "differences in nutrient or productivity settings between the sites are likely influencing the response of Noelaerhabdaceae coccolith weight," or that weight increases could be due to "an abundance shift to heavily calcifying morphotypes, such as the increase of an over-calcified type of E. huxleyi, even during times of decreasing carbonate ion concentration."

What it means
In their last words on the subject, Berger et al. write that "the high natural variability of coccolith weight during the Holocene raises the question as to whether future changes in the carbonate system of the oceans will have a positive or negative effect on coccolithophore calcification," which is something that most climate alarmists likely have never even considered.

Reviewed 16 July 2014