CO2 could take huge toll on ocean fish by mid-century

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Can the world’s oceans survive the global warming era?

Not much time left to cut greenhouse gas pollution

Staff Report

Building levels of carbon dioxide in the atmosphere and oceans could have a widespread and devastating effect on many fish by 2050, Australian researchers warned in a new study.

“Our results were staggering and have massive implications for global fisheries and marine ecosystems across the planet,” said Dr. Ben McNeil, a researcher at the University of New South Wales 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,” McNeil said.The study found that CO2 could reach those dangerous levels many decades sooner than previously thought, with serious implications for the world’s fisheries.

“We’ve shown that, if atmospheric carbon dioxide pollution continues to rise, fish and other marine creatures in CO2 hotpots in the Southern, Pacific and North Atlantic oceans will experience episodes of hypercapnia by the middle of this century,” he said. “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. The UNSW scientists utilised a global database of seawater carbon dioxide concentrations collected during the past 30 years as part of a variety of oceanographic programs.

The modeling in the study showed the natural CO2 cycles will be amplified by up to tenfold in some regions of the ocean by the end of the century, if atmospheric carbon dioxide concentrations continue to rise.

To help accelerate this important area of research, the UNSW scientists have also offered prizes to other researchers who can improve on their results.

“Predicting the onset of hypercapnia is difficult, due to a lack of global ocean measurements of carbon dioxide concentrations,” Dr McNeil said. “We are challenging other scientists with innovative predictive approaches to download the dataset we used, employ their own numerical methods and share their final predictions, to see if they can beat our approach.”

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