From a Hansen Testimony Critique pdf ( http://www.co2science.org/scripts/CO2ScienceB2C/education/reports/hansen/HansenTestimonyCritique.pdf ) I found this in June:

Quote:
There is the argument that CO2 will acidify the oceans thereby hampering the calcification process of reefs. "In a study of calcification rates of massive Porites coral colonies on Australia’s Great Barrier Reef (GBR), Lough and Barnes (1997) found that 'the 20th century has witnessed the second highest period [our italics] of above average calcification in the past 237 years'" pg 21