Physical and chemical changes in the ocean over basin-wide zones and decadal or longer time-scales: perspectives on current and future conditions - Ocean Sustainability in the 21st Century - page 96

The dissolution of carbonate from the ocean floor will increase. Ecological changes
due to acidification can be severe for corals, for pelagic ecosystems, and for the marine
food web at higher trophic levels. Acidification may lead to shifts in ocean ecosystem
structure and dynamics, which may alter the biological production and export from the sur-
face of organic carbon and calcium carbonate. Models suggest that the overall effect of
carbon-climate interactions is a positive feedback, giving higher CO 2 than models not in-
cluding coupling or interactions.
Acidification of the ocean has occurred throughout geological periods, possibly
mainly due to volcanic activity. However, recent reviews, such as that of Zeebe ( 2012 ) ,
conclude that none of the mass extinctions in the last 450 million years is a good analogue
of what we might expect over the next century, primarily because the ongoing ocean
acidification is occurring faster than any that is documented in the paleo-record. Past
catastrophic-type activities have lasted thousands of years. Human activities have gener-
ated a serious acidification over decadal time-scales, and there is little indication that we
are yet doing anything effective to reduce fossil fuel emissions.