Oceans Passing Critical CO2 Threshold

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By Stephen Leahy

UXBRIDGE, Canada, Nov 24 (IPS)

An apparent rapid upswing in ocean acidity in recent years is wiping out coastal species like mussels, a new study has found.

“We’re seeing dramatic changes,” said Timothy Wootton of the Department of Ecology and Evolution at the University of Chicago, lead author of the study published Monday in the Proceedings of the National Academy of Sciences. The study shows increases in ocean acidity that are more than 10 times faster than any prediction.

“It appears that we’ve crossed a threshold where the ocean can no longer buffer the effects of CO2 in the atmosphere,” Wootton told IPS.

For millions of years, the levels of carbon dioxide in the atmosphere and the ocean were in balance, but the burning of fossil fuels and deforestation has put more CO2 into the atmosphere over the last 150 years. The oceans have absorbed one-third — about 130 billion tonnes — of those human emissions and have become 30 percent more acidic as the extra CO2 combines with carbonate ions in seawater, forming carbonic acid.

Each day, the oceans absorb 30 million tonnes of CO2, gradually and inevitably increasing their acidity. There is no controversy about this basic chemistry; however, there is disagreement about the rate at which the oceans are becoming acidic and the potential impact. Continue reading