The Rate of Current Ocean Acidification

a. A December 2009 National Geographic report quoted Thomas Lovejoy, former chief biodiversity advisor to the World Bank on recent research suggesting "the acidity of the oceans will more than double in the next 40 years. This rate is 100 times faster than any changes in ocean acidity in the last 20 million years, making it unlikely that marine life can somehow adapt to the changes.

http://blogs.nationalgeographic.com/blogs/news/chiefeditor/2009/12/acidification.html

b. According to research, from the University of Bristol, published in the journal Nature Geoscience in February 2010, compared current rates of ocean acidification with the greenhouse event at the Paleocene-Eocene boundary, about 55 million years ago when surface ocean temperatures rose by 5-6 degrees Celsius, during which time no catastrophe is seen in surface ecosystems, yet bottom-dwelling organisms in the deep ocean experienced a major extinction. They concluded that the current acidification is on path to reach levels higher than any seen in the last 65 million years

http://www.physorg.com/news185444922.html

c. The study also found that the current rate of acidification is "ten times the rate that preceded the mass extinction 55 million years ago," and Ridgwell commented that the present rate "is an almost unprecedented geological event.

[Note that this time it's "only" 10 times but not 10 times faster than any previous normal time in that many years, but 10 times faster than the atypical and dangerous mass-extinction event 55 million of years ago]

http://e360.yale.edu/content/feature.msp?id=2241

d. A July 2010 article in Scientific American quoted marine geologist William Howard of the Antarctic Climate and Ecosystems Cooperative Research Center in Hobart, Tasmania stating that "the current rate of ocean acidification is about a hundred times faster than the most rapid events" in the geologic past.

http://www.scientificamerican.com/article.cfm?id=ancient-ocean-acidification-intimates-long-recovery-from-climate-change

"The natural pH of the ocean is determined by a need to balance the deposition and burial of CaCO₃ on the sea floor against the influx of Ca²⁺ and CO2-3 into the ocean from dissolving rocks on land, called weathering. These processes stabilize the pH of the ocean, by a mechanism called CaCO₃ compensation...The point of bringing it up again is to note that if the CO₂ concentration of the atmosphere changes more slowly than this, as it always has throughout the Vostok record, the pH of the ocean will be relatively unaffected because CaCO₃ compensation can keep up. The [present] fossil fuel acidification is much faster than natural changes, and so the acid spike will be more intense than the earth has seen in at least 800,000 years." http://www.realclimate.org/index.php/archives/2005/07/the-acid-ocean-the-other-problem-with-cosub2sub-emission/