By Matt McGrath, Environment correspondent
13 November 2013
(BBC News) – The world's oceans are becoming acidic at an "unprecedented rate" and may be souring more rapidly than at any time in the past 300 million years.
In their strongest statement yet on this issue, scientists say acidification could increase by 170% by 2100.
They say that some 30% of ocean species are unlikely to survive in these conditions.
The researchers conclude that human emissions of CO2 are clearly to blame.
The study will be presented at global climate talks in Poland next week.
In 2012, over 500 of the world's leading experts on ocean acidification gathered in California. Led by the International Biosphere-Geosphere Programme, a review of the state of the science has now been published.
This Summary for Policymakers states with "very high confidence" that increasing acidification is caused by human activities which are adding 24 million tonnes of CO2 to oceans every day.
The addition of so much carbon has altered the chemistry of the waters.
Since the start of the industrial revolution, the waters have become 26% more acidic.
"This is the state of the art," said Prof Jean-Pierre Gattuso, from CNRS, the French national research agency.
"My colleagues have not found in the geological record, rates of change that are faster than the ones we see today."
What worries the scientists is the potential impact on many ocean species including corals.
Studies carried out at deep sea vents where the waters are naturally acidic thanks to CO2, indicate that around 30% of the ocean's biodiversity may be lost by the end of this century.
These vents may be a "window on the future" according to the researchers.
"You don't find a mollusc at the pH level expected for 2100, this is really quite a stunning fact," said Prof Gattuso. [more]