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Oceans Turning Acid at ‘Unparalleled’ Rate

The world’s oceans are turning acidic at what could be the fastest pace of any time in the past 300 million years. That’s the conclusion of a new study published in the journal Science.

The reason lies in the amount of carbon dioxide being absorbed by the seas.

The last time anything like this happened was during a major period of planet-warming carbon 56 million years ago. But this time it’s happening even faster.

A research team studied 300 million years’ worth of data on global warming and acidifying oceans, and found the current rate of acidification is also greater than three other major periods of climate change in the Earth’s history, including the the impact of the asteroid which wiped out the dinosaurs, and the Permian mass-extinction 252 million years ago, when 95 per cent of life on Earth was destroyed.

Coral reefs are especially endangered by ocean acidification. (Photo by Ko Sasaki.)

As seawater becomes more acid, it eats away at coral reefs, which which are homes for other animals and plants, and makes it harder for creatures with shells to form those shells, as well as interfering with sea life all up and down the food chain.

“This raises the possibility that we are entering an unknown territory of marine ecosystem change,” said Professor Andy Ridgwell or Bristol University.

Human activities, including the burning of fossil fuels, have increased the level of atmospheric carbon to 392 parts per million from about 280 parts per million at the start of the industrial revolution. 350 parts per million is considered the highest level before irreversible climate change kicks in.

“Given that the rate of change [56 million years ago] was an order of magnitude smaller compared to what we’re doing today, and still there were these big ecosystem changes, that gives us concern for what is going to happen in the future,” said study author Baerbel Hoenisch.

Richard Feely, an oceanographer at the U.S. National Oceanic and Atmospheric Administration who was not involved in the study, said looking at that distant past was a good way to foresee the future.

“These studies give you a sense of the timing involved in past ocean acidification events – they did not happen quickly,” he said in a statement. “The decisions we make over the next few decades could have significant implications on a geologic timescale.”