PERILS FOR THE OCEANS - The Climate Casino - page 114

reduces atmospheric concentrations, it also causes changes in ocean
chemistry.
The chemistry is relatively straightforward. When CO 2 dissolves in
the oceans, it makes the oceans more acidic and lowers the concentra-
tions of calcium carbonate. 17 Many marine organisms form shells from
calcium carbonate, including corals, mollusks, crustaceans, and some
plankton. Because climate change and ocean acidifi cation are both
caused by increasing atmospheric CO 2 , acidifi cation is sometimes re-
ferred to as “the other CO 2 problem.”
Ocean acidifi cation has several important features. First, it depends
primarily on the carbon cycle and does not have the uncertainties as-
sociated with climate modeling. Either because the chemistry is hard
to challenge, or because the trend is clear, there is little controversy
about ocean acidifi cation. I have not yet read that ocean acidifi cation is
a hoax.
Second, the entire phenomenon was only recently recognized. The
fi rst major publications appeared over the past decade. 18 Indeed, the bio-
logical problems of acidifi cation were not even recognized in the IPCC
Third Assessment Report of 2001. This is a sobering example of what
we call “inevitable surprises.”
Third, the major predictions of the ocean acidifi cation hypothesis
have been confi rmed by measurements in the world's oceans. There is a
tight link between atmospheric and oceanic CO 2 concentrations and
the falling pH (rising acidity) of the oceans. 19
Marine scientists are just beginning to reckon with the consequ-
ences of acidifi cation on ocean organisms and ecosystems. I discussed in
Chapter 5 the warning from marine biologists about the catastrophic
decline in corals that is already beginning and is likely to become ir-
reversible if CO 2 concentrations continue their trend for two or three
decades.
Field experiments indicate a complex set of responses to ocean
acidifi cation. In many of the organisms studied (particularly corals and
mollusks), the rate of calcifi cation and reproduction slows with higher
CO 2 concentrations, and this is especially pronounced at high latitudes.
These changes will lead to a major redistribution of species, with those