The term ocean acidification is used to describe the ongoing
decrease in ocean pH caused by human CO2 emissions, such
as the burning of fossil fuels. It is the little known consequence
of living in a high CO2 world, dubbed at the
2009 United Nations Climate Change Conference
(COP15) as the “evil twin of climate change”.
The oceans currently absorb approximately half of the
CO2 produced by burning fossil fuel; put simply,
climate change would be far worse if it were not for the oceans.
However, there is a cost to the oceans - when CO2
dissolves in seawater it forms carbonic acid and as more
CO2 is taken up by the oceans surface, the pH
decreases, moving towards a less alkaline and therefore more acidic
state.
Already ocean pH has decreased by about 30%
and if we continue emitting CO2 at the same rate by
2100 ocean acidity will increase by about 150%, a rate that
has not been experienced for at least 400,000 years. Such a
monumental alteration in basic ocean chemistry is likely to have
wide implications for ocean life, especially for those organisms
that require calcium carbonate to build shells or skeletons.
Ocean acidification is a relatively new field
of research, with most of the studies having been conducted over
the last decade. While it is gaining some attention among policy
makers, international leaders and the media, scientists find there
is still a lack of understanding.