The European Journal of Phycology doesn’t have the same ring (or distribution) as the journal Science. But last week, eclipsed by Iglesias-Rodriguez et al, a group of American and Chinese researchers published results from studies in which they tested growth of Ehux under varying conditions of temperature, pCO2, and irradiance, and their influence on each other. They write, “We documented a trend of decreased cellular PIC/POC [the ratio of particulate inorganic to organic carbon] production under greatly increased irradiance in our E. huxleyi strain. If this is the case for most calcifying strains of this ecologically dominant marine coccolithophore, then future mixed layer shallowing could potentially have a large impact on the export of PIC relative to POC into the deep ocean (the marine rain ratio) and on the whole marine carbon cycle.” [p 95]

The heightened irradiance would come from changes in ocean stratification, circulation, cloud cover and sea ice cover, brought about by warming, the influx of freshwater into oceans from melting ice, and changing rainfall patterns. (See Feng et al. “Interactive effects of increased pCO2, temperature and irradiance on the marine coccolithophore Emiliania huxleyi (Prymniesiophyceae).” European Journal of Phycology, 43:1, 87-98).

This was pointed out to me by one of the authors of the Science paper, who wrote the other day: “The evidence is not all unanimous for coccos, with some studies showing detrimental effects, others not. For instance, another large study was just published last week, and they found reduced calcification at high CO2, in line with the earlier work and contradictory to our study. And they bubbled with CO2 rather than adding acid, i.e. the ‘correct’ way.”