Diver in vent field
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'Jacuzzi vents' model CO2 future

A UK scientist studying volcanic vents in the ocean says they hold a grave warning for future marine ecosystems.

These vents have naturally acidified waters that hint at how our seas might change if atmospheric carbon dioxide levels continue to rise.

They are conditions that would make it harder for corals and similar organisms to make the hard parts in their bodies.

Dr Jason Hall-Spencer's work suggests our oceans could lose perhaps 30% of their biodiversity this century. He described his experiments to our correspondent Jonathan Amos.