Calcifying Coccolithophores off the California Coast

Authors Grelaud et al. (2009) write that "coccolithophores are unicellular pelagic algae that represent a large part of the world ocean's nannophytoplankton and play a significant role in the carbon cycle as major producers of biogenic calcium carbonate," stating that "the inorganic fossil remains of coccolithophores consist of <20µm calcareous plates called coccoliths," the small size and large abundance of which "make it possible to sample marine sediment cores at mm to sub-mm intervals with ultra-high resolution." Against this backdrop and "in the context of modern global warming and ocean acidification due to anthropogenic CO₂ release," Grelaud et al. "investigated the morphometry (size, weight) of selected species of the order Isochrysidales (i.e., E. huxleyi, G. muellerae and G. oceanica) to understand how coccolithophores' carbonate mass is influenced by recent oceanographic global changes." This they did for sediment cores taken from "the deep center of the Santa Barbara Basin (SBB) on the North American Pacific margin in the interval from AD 1917 to 2004."

Based on their analysis, the three researchers report that "morphometric parameters measured on E. Huxleyi, G. muellerae and G. oceanica indicate increasing coccolithophore shell carbonate mass from ~1917 until 2004 concomitant with rising pCO₂ and sea surface temperature in the region of the SBB." More specifically, they say that "a >33% increase in mean coccolith weight was determined for the order Isochrysidales over 87 years from ~1917 until 2004."Given these findings, Grelaud et al. write that "the last century has witnessed an increasing net influx of atmospheric carbon dioxide into the world's oceans, a rising of pCO₂ of surface waters, and under-saturation with respect to aragonite, especially along the North American Pacific margin," which was the site of their study. These conditions, as they describe it, have been predicted by climate alarmists "to result in reduced coccolithophore carbonate mass and a concomitant decrease in size and weight of coccoliths [italics added]." As indicated by Grelaud et al.'s study, however, just the opposite appears to be the case in the real world, even in places where the predicted calcification reductions are expected to be greatest, as has also been demonstrated to be the case by the work of Iglesias-Rodriguez et al. (2008), who observed -- in the words of Grelaud et al. -- "a 40% increase in average coccolith weight across the last 220 years, as recorded in a box core from the subpoloar North Atlantic," and as has been further confirmed by the complimentary work of Halloran et al. (2008).

Additional References
Halloran, P.R., Hall, I.R., Colmenero-Hidalgo, E. and Rickaby, R.E.M. 2008. Evidence for a multi-species coccolith volume change over the past two centuries: understanding a potential ocean acidification response. Biogeosciences 5: 1651-1655.

Iglesias-Rodriguez, M.D., Halloran, P.R., Rickaby, R.E.M., Hall, I.R., Colmenero-Hidalgo, E., Gittins, J.R., Green, D.R.H., Tyrrell, T., Gibbs, S.J., von Dassow, P., Rehm, E., Armbrust, E.V. and Boessenkool, K.P. 2008. Phytoplankton calcification in a high-CO₂ world. Science 320: 336-340.