It can be said that there isa consensus in scientific knowledge that ocean acidification already havinghigh impacts on many ocean species and ecosystems.1 Manymarine photosynthetic organisms and animals, such as molluscs, corals,echinoderms, foraminifera and calcareous algae, make shells and plates out ofcalcium carbonate.2 It could happened when the seawater contains asufficient concentration of calcium carbonate.
Increased concentrations of CO2 will increase acidity which impedes the process ofcalcification. Calcifying organisms will be negatively affected in the presentcentury, with estimates suggesting that calcification rates will decrease by asmuch as 50 percent by 2100 due to the fall in calcium carbonate concentration.3Calcium carbonate is employed as aconstruction material for organisms in several crystalline forms, such asaragonite and calcite. All calcifying organisms are likely to be adverselyaffected by ocean acidification, but those that use aragonite will be affectedfirst as aragonite dissolves more readily due to its crystalline structure.4 At most risk are coral organisms that require aragonite to bedeposited in excess of erosion to build coral reefs and if oceanic pH falls by as much as 0.4 pH units by 2100,carbonate levels could potentially drop below those required to sustain coralreef accretion by 2050.
51 See, G. De’ath et al.,”Declining coral calcification on the Great Barrier Reef”, 323 Science (2009),116. 2 Royal Society, Oceanacidification due to increasing atmospheric carbon dioxide (2005), in Rachel Baird, op cit, 5.3 OSPAR Commission, Effects on the marine environment of oceanacidification resulting from elevated levels of CO2 in theatmosphere (2006). See also, M.Sakashita, “Petition to regulate carbon dioxide pollution under the FederalClean Water Act”, 2007 4 WGBU, Special Report 2006: The future oceans, warming up, risinghigh, turning sour (2006) 5 W.
Burns, “Anthropogenic carbon dioxide emissions and oceanacidification”, in R.A. Askins et al. (eds), Saving Biological Diversity (Berlin:Springer, 2008), 187. See also, Hoegh-Guldberg, loc cit.