Carbon dioxide concentrations in seawater could reach levels high enough to make fish "intoxicated" and disoriented many decades earlier than previously thought.
The University of South Wales' study, published in the journal Nature, is the first global analysis of the impact of rising carbon dioxide emissions from fossil fuels on natural variations in carbon dioxide concentrations in the world's oceans.
"Our results were staggering and have massive implications for global fisheries and marine ecosystems across the planet," says lead author, Dr Ben McNeil, of the UNSW Climate Change Research Centre.
"High concentrations of carbon dioxide cause fish to become intoxicated — a phenomenon known as hypercapnia. Essentially, the fish become lost at sea. The carbon dioxide affects their brains and they lose their sense of direction and ability to find their way home. They don't even know where their predators are.
"We've shown that if atmospheric carbon dioxide pollution continues to rise, fish and other marine creatures in CO2 hotspots in the Southern, Pacific and North Atlantic oceans will experience episodes of hypercapnia by the middle of this century — much sooner than had been predicted, and with more damaging effects than thought.
"By 2100, creatures in up to half the world's surface oceans are expected to be affected by hypercapnia."
Ocean hypercapnia is predicted to occur when atmospheric carbon dioxide concentrations exceed 650 parts per million.
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