The oceanic alarm comes from:
Orr, James C. et al., 2005. Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature Vol. 437, No 7059, pp. 681-686, September 29, 2005
Abstract
Today's surface ocean is saturated with respect to calcium carbonate, but increasing atmospheric carbon dioxide concentrations are reducing ocean pH and carbonate ion concentrations, and thus the level of calcium carbonate saturation. Experimental evidence suggests that if these trends continue, key marine organisms—such as corals and some plankton—will have difficulty maintaining their external calcium carbonate skeletons. Here we use 13 models of the ocean−carbon cycle to assess calcium carbonate saturation under the IS92a 'business-as-usual' scenario for future emissions of anthropogenic carbon dioxide. In our projections, Southern Ocean surface waters will begin to become undersaturated with respect to aragonite, a metastable form of calcium carbonate, by the year 2050. By 2100, this undersaturation could extend throughout the entire Southern Ocean and into the subarctic Pacific Ocean. When live pteropods were exposed to our predicted level of undersaturation during a two-day shipboard experiment, their aragonite shells showed notable dissolution. Our findings indicate that conditions detrimental to high-latitude ecosystems could develop within decades, not centuries as suggested previously."
and
The Royal Society, 2005. Ocean acidification due to increasing atmospheric carbon dioxide. Policy document 12/05, June 2005, online http://www.royalsoc.ac.uk/displaypagedoc.asp?id=13314
..which elicited this comment:
Junkscience.com (Steven Milloy) comments July 1, 2005:
“Hmm... The Royal Society sure has a bee in its collective bonnet over anthropogenic greenhouse emissions lately.
Check out the Ordovician Mass Extinction. Note that fauna of the period included large diversity of corals, bryozoans, bivalves and gastropods (we know most about these because shells and skeletal remains fossilise best). In fact, reef builders took something of a hiding in Earth's second-most devastating mass extinction event.
Why is this significant? Well, all these shelled and reef building critters were apparently doing fine when atmospheric carbon dioxide levels were an order of magnitude greater than current and anticipated levels. If these creatures, many of whose descendants are current denizens of the seas, managed to fashion calcium carbonate shells and skeletons then it would appear that atmospheric CO2 levels are not a major determinant of the success of these marine creatures. Why would apparently insignificant levels be a problem now?”
Something like that seems so be confirmed by
Pelejero, Carles, Eva Calvo, Malcolm T. McCulloch, John F. Marshall, Michael K. Gagan, Janice M. Lough, and Bradley N. Opdyke, 2005. Preindustrial to Modern Interdecadal Variability in Coral Reef pH. Science Vol. 309, No 5744, pp. 2204-2207, September 30, 2005
The oceans are becoming more acidic due to absorption of anthropogenic carbon dioxide from the atmosphere. The impact of ocean acidification on marine ecosystems is unclear, but it will likely depend on species adaptability and the rate of change of seawater pH relative to its natural variability. To constrain the natural variability in reef-water pH, we measured boron isotopic compositions in a 300-year-old massive Porites coral from the southwestern Pacific. Large variations in pH are found over 50-year cycles that covary with the Interdecadal Pacific Oscillation of ocean-atmosphere anomalies, suggesting that natural pH cycles can modulate the impact of ocean acidification on coral reef ecosystems.
The authors developed a reconstruction of seawater pH spanning the period 1708-1988, based on the boron isotopic composition (d11B) of a long-lived massive coral (Porites) from Flinders Reef in the western Coral Sea of the southwestern Pacific.
"there is no notable trend toward lower d11B values over the 300-year period investigated.
…."the dominant feature of the coral d11B record is a clear interdecadal oscillation of pH, with d11B values ranging between 23 and 25 per mil (7.9 and 8.2 pH units)," which "is synchronous with the Interdecadal Pacific Oscillation." Furthermore, they calculated changes in aragonite saturation state from the Flinders pH record that varied between ~3 and 4.5, which values encompass "the lower and upper limits of aragonite saturation state within which corals can survive." Despite this fact, they report that "skeletal extension and calcification rates for the Flinders Reef coral fall within the normal range for Porites and are not correlated with aragonite saturation state or pH
Pelejero et al.'s 300-year record of these parameters began "well before the start of the Industrial Revolution" provides no evidence of any anthropogenic decline. They found that huge cyclical changes in the parameters had essentially no detectable effect on either coral calcification or skeletal extension rates and consequently the sensitivity of coral calcification rate to changes in pH and aragonite saturation state is much less than the alarmists claim to be.
