The world’s oceans are
becoming more acid, with potentially devastating consequences for corals and
the marine organisms that build reefs and provide much of the Earth’s
breathable oxygen.
The acidity is caused by the
gradual buildup of carbon dioxide (CO2) in the atmosphere, dissolving into the
oceans. Scientists fear it could be lethal for animals with chalky skeletons
which make up more than a third of the planet’s marine life….
Corals and plankton with
chalky skeletons are at the base of the marine food web. They rely on sea water
saturated with calcium carbonate to form their skeletons. However, as acidity
intensifies, the saturation declines, making it harder for the animals to form
their skeletal structures (calcify).
“Analysis of coral cores shows
a steady drop in calcification over the last 20 years,” says Professor Ove
Hoegh-Guldberg of CoECRS and the University of Queensland. “There’s not much
debate about how it happens: put more CO2 into the air above and it dissolves
into the oceans.
“When CO2 levels in the
atmosphere reach about 500 parts per million, you put calcification out of
business in the oceans.”
(Atmospheric CO2 levels are presently 385 ppm, up from 305 in 1960.)
