Geoscience Reference
In-Depth Information
depending upon calcifi cation declining and the noncalcifi ers increas-
ing. There is evidence of a sharp increase in ocean CO
2
during an epi-
sode known as the Paleocene-Eocene thermal maximum (PETM), 55
million years ago. Based on data from earlier episodes of spiking CO
2
like the PETM, it appears that most species survived, but we should
expect the current increase in CO
2
to result in the extinction of some
species.
The impacts upon humans and the economy are most easily seen
for fi sheries. Those species most likely to be harmed are oysters, corals,
plankton, and shellfi sh. The magnitude of losses, and the extent to
which the losses in human consumption can be replaced by fi sh farms
or other foods, is unclear at this point. Some studies have found that
the mortality rate of fi sh increases dramatically as CO
2
concentrations
rise above three times current levels.
20
Ocean acidifi cation is one of the most troubling features of CO
2
ac-
cumulation. It is an extreme example of an unmanageable system. Hu-
mans are likely to add at least 3 to 4 trillion tons of CO
2
to the upper
layer of the oceans by 2100. There are no easy technological solutions
here. We will see later that geoengineering solutions to the climate-
change problem may slow warming, but they will do almost nothing to
address ocean acidifi cation.
Moreover, while it is reassuring that the earth has previously expe-
rienced spikes in CO
2
concentrations similar to that which humans are
causing, the distribution of species in earlier periods was different, and
we do not have reliable records of how different species fared in those
periods. Because the oceans are so complex, even with the most tal-
ented and diligent scientists trying to understand its consequences, we
are unlikely to have a full understanding of the impacts of ocean acidi-
fi cation until they are upon us.
