Increasing carbonic acid levels in the world’s oceans are due to the water absorbing carbon dioxide from the air.

The source of that greenhouse gas is the burning of fossil fuels.

The water’s pH is now dropping faster than at any other time in the past 300 million years.

When this is combined with natural upwelling of more acidic waters from the deep, at least one creature has been found to be unable to cope with the more caustic waters.

Writing in the journal Nature Geoscience, British Antarctic Survey researcher Geraint Tarling said he and colleagues have found that the free-swimming sea snails called pteropods, Limacina helicina antarctica, are being eaten away by unusual corrosion in the Southern Ocean.

The changing ocean chemistry may also eliminate the aragonite that many creatures, such as corals and molluscs need to build their shells as early as 2050 in some parts of the world, the researchers caution.

Images: Nina Bednarsek and Bernard Lézé