Global warmingCoral, shellfish and thousands of other species are in danger because the sea is becoming increasingly acidic, scientists warned yesterday.
A British Royal Society report has said carbon dioxide (CO2) emissions are making the oceans increasingly acid and that they are now on an irreversible path which will mean that by 2100 seawater will be more acidic than for hundreds of millennia.
The report authors said it was further evidence for world leaders at the G8 to cut emissions to less than half what they are today - well beyond the scope of the Kyoto protocol.
Oceans act as a giant sponge, taking up carbon dioxide from the atmosphere which dissolves and forms an acid in seawater.
Over the next 100 years, the oceans will become more acidic by 0.5 of a Ph unit on the 14-point scale, according to the society's report.
Sea creatures such as corals, shellfish, sea urchins and starfish will suffer most because acidity levels will make it harder for them to form their skeletons and shells.
By 2050 corals could be rare on tropical and sub-tropical reefs including the Great Barrier Reef, with knock-on effects for hundreds of thousands of species and people.
The worst effects are expected to be in the Antarctic ocean where plankton which cover vast areas could be the first victims, causing problems for the animals that feed on them.
High CO2 levels may also make it harder for fish and other large marine animals to obtain oxygen from seawater.
Prof John Raven, chair of the society's working group on ocean acidification, said: "Our world leaders meeting at the G8 summit must commit to taking decisive and significant action to cut carbon dioxide emissions."