Impacts of Ocean Acidification on Coral Reefs and Other Marine Calcifiers: Report released by NSF, NOAA & USGS. Extract from the executive summary: A variety of evidence indicates that [due to ocean uptake of anthropogenic CO2] calcification rates will decrease, and carbonate dissolution rates increase, as CaCO3 saturation state decreases. This evidence comes from principles of thermodynamics, the geologic record, and the evolutionary pathways of CaCO3 secreting organisms. Further evidence, from controlled experiments of biocalcification under increased CO2 conditions, confirms that calcification rates of many organisms decrease with decreasing CaCO3 saturation state.

Extrapolation of these results to the real world suggests that calcification rates will decrease up to 60% within the 21st century. We know that such extrapolations are oversimplified and do not fully consider other environmental and biological effects (e.g., rising water temperature, biological adaptation); nor do they address effects on organism fitness, community structure, and ecosystem functioning. Any of these factors could increase or decrease the laboratory-based estimates, but it is certain that net production of CaCO3 will decrease in the future.

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