The other day I went to a lecture by one of Britain’s leading marine scientists. His talk was on the “Other CO2 Problem,” which is not the problem of rising CO2 levels in the atmosphere, but of rising acidity in the world’s oceans.

The oceans absorb about a third of the CO2 released into the atmosphere by human activities. But when the gas dissolves in sea water it alters the ocean’s delicate chemical balance.

Now new research from the Pacific backs up these concerns. Water samples collected around an island in the eastern Pacific over the past eight years showed seawater had acidified more than 20 times faster than scientists expected.

The reason this is so important – and devastating – for shellfish and other crustaceans, is that acidic waters dissolve calcium carbonate used by the organisms to make their protective shells. So these organisms will no longer be able to make hard shells.

The increasing acidification of the oceans is likely to have impacts that run throughout the marine ecosystem, because the organisms most affected are at the bottom of the foodchain.

Timothy Wootton, a biologist at the University of Chicago, led a team of researchers who analysed the acidity, salinity and temperature of water around Tatoosh Island off the northwestern coast of Washington state.

Writing in the US journal Proceedings of the National Academy of Sciences, the scientists raise concerns at how rapidly the process is happening and the impact it could have. “Acidification may be a more urgent issue than previously predicted, at least in some areas of the ocean,” the authors write.

The rise in acidity is likely to cause substantial falls in the numbers of mussels and barnacles. In turn, the changing distribution of these organisms will have effects on marine life that feed on them.

In dealing with climate change it is all too easy to just think about the atmosphere, but we need to remember the seas too.