How does rising atmospheric CO2 affect marine organisms?

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Surface and Bottom Water Temperatures of the North Atlantic Current off the Coast of Europe
Eiriksson, J., Bartels-Jonsdottir, H.B., Cage, A.G., Gudmundsdottir, E.R., Klitgaard-Kristensen, D., Marret, F., Rodrigues, T., Abrantes, F., Austin, W.E.N., Jiang, H., Knutsen, K.-L. and Sejrup, H.-P. 2006. Variability of the North Atlantic Current during the last 2000 years based on shelf bottom water and sea surface temperatures along an open ocean/shallow marine transect in western Europe. The Holocene 16: 1017-1029.

What was done
The authors reconstructed the near-shore thermal history of the North Atlantic Current along the western coast of Europe over the last two millennia, based on measurements of stable isotopes, benthic and planktonic foraminifera, diatoms and dinoflagellates, as well as geochemical and sedimentological parameters, which they acquired on the Iberian margin, the West Scotland margin, the Norwegian margin and the North Icelandic shelf.

What was learned
In addition to identifying the Roman Warm Period (nominally 50 BC- AD 400), which exhibited the warmest sea surface temperatures of the last two millennia on both the Iberian margin and the North Icelandic shelf) and the following Dark Ages Cold Period (AD 400-800), Eiriksson et al. report detecting the Medieval Warm Period (AD 800-1300) and the Little Ice Age (AD 1300-1900), which was followed in some records by a strong warming to the present. However, they make a point of stating that this latter warming "does not appear to be unusual when the proxy records spanning the last two millennia are examined."

What it means
The results of Eiriksson et al.'s research once again reveal the presence of the millennial-scale climatic oscillation that has been responsible for periodically producing centennial-scale warm and cold periods throughout earth's history. It also reveals there is nothing unusual or unnatural about the Current Warm Period, which in the case of two of their four sites was found to be somewhat cooler than it was during the Roman Warm Period of 2000 years ago, when the atmosphere's CO2 concentration was over 100 ppm less than it is today.

In light of these several observations we feel there is no compelling reason to believe the climate-alarmist claims that (1) the earth has experienced unprecedented warming over the past several decades, and that (2) that warming was driven by the historical increase in the atmosphere's CO2 concentration. In fact, there is much compelling evidence that leads us to disbelieve their contentions. With respect to the specific subject matter of this review, for example, see Climate Oscillations (Millennial Variability) in our Subject Index.

Reviewed 18 July 2007