How does rising atmospheric CO2 affect marine organisms?

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A Tempering of Thought on CO2-Induced Ocean Acidification
Volume 13, Number 7: 17 February 2010

Concerns about the viability of earth's corals and other calcifying organisms in a CO2-accreting atmosphere were brought to the forefront of the climate-alarmist attack on anthropogenic CO2 emissions with the publication of the papers of Kleypas et al. (1999) and Langdon et al. (2000), wherein it was claimed that the ongoing rise in the air's CO2 content was slowly but surely lowering oceanic pH, making it ever harder for calcifying organisms to produce their calcium carbonate skeletons and possibly leading to their extinction. As more and more pertinent studies have been conducted, however, this extreme view has been greatly tempered, as indicated by the recent review of the subject by Doney et al. (2008).

The four marine science researchers -- of whom Kleypas herself is one -- report that many calcifying species do indeed "exhibit reduced calcification and growth rates in laboratory experiments under high-CO2 conditions," but they also report that "some photosynthetic organisms (both calcifying and non-calcifying) have higher carbon fixation rates under high CO2." And as Idso et al. (2000) have noted in the case of corals, the "photosynthetic activity of zooxanthellae is the chief source of energy for the energetically-expensive process of calcification," and much evidence suggests, in their words, that "long-term reef calcification rates generally rise in direct proportion to increases in rates of reef primary production."

Due to these divergent observations, plus the fact that most of what we know about the topic "stems largely from short-term laboratory and mesocosm experiments," as Doney et al. describe them, the latter scientists conclude that the ultimate long-term response of "individual organisms, populations, and communities to more realistic gradual changes [in atmospheric CO2 concentration] is largely unknown." Additionally acknowledging, therefore, that "the broader implications for ocean ecosystems are not well known," they state that "the impact of rising CO2 on marine biota will be more varied than previously thought." That is to say, it will not be one grand catastrophe for earth's calcifying marine life. Rather, there may well be both "winners and losers," as they put it, with the vast bulk of species likely sandwiched somewhere in between these two extremes. In fact, when real-world evidence for rapid adaptation and evolution is considered, the future actually looks quite bright for earth's aquatic (and terrestrial) life (Idso, 2009; Idso and Idso, 2009).

Sherwood, Keith and Craig Idso

Doney, S.C., Fabry, V.J., Feely, R.A. and Kleypas, J.A. 2008. Ocean acidification: the other CO2 problem. Annual Review of Marine Science 1: 169-192.

Idso, C.D. 2009. CO2, Global Warming and Coral Reefs: Prospects for the Future. Vales Lake Publishing, LLC, Pueblo West, Colorado, USA.

Idso, C.D. and Idso, S.B. 2009. CO2, Global Warming, and Species Extinctions: Prospects for the Future. Vales Lake Publishing, LLC, Pueblo West, Colorado, USA.

Idso, S.B., Idso, C.D. and Idso, K.E. 2000. CO2, global warming and coral reefs: Prospects for the future. Technology 7S: 71-94.

Kleypas, J.A., Buddemeier, R.W., Archer, D., Gattuso, J-P., Langdon, C., and Opdyke, B.N. 1999. Geochemical consequences of increased atmospheric carbon dioxide on coral reefs. Science 284: 118-120.

Langdon, C., Takahashi, T., Sweeney, C., Chipman, D., Goddard, J., Marubini, F., Aceves, H., Barnett, H. and Atkinson, M.J. 2000. Effect of calcium carbonate saturation state on the calcification rate of an experimental coral reef. Global Biogeochemical Cycles 14: 639-654.