Acidifying oceans pose danger to coral reefs

By Michael Christie

FORT LAUDERDALE, Florida (Reuters) - Like a tooth dipped in a glass of Coca-Cola, coral reefs, lobsters and other marine creatures that build calcified shells around themselves could soon dissolve as climate change turns the oceans increasingly acidic.

The carbon dioxide spewed into the atmosphere by factories, cars and power plants is not just raising temperatures. It is also causing what scientists call "ocean acidification" as around 25 percent of the excess CO2 is absorbed by the seas.

The threat to hard-bodied marine organisms, such as coral reefs already struggling with warming waters, is alarming, and possibly quite imminent, marine scientists gathered this week for a coral reef conference in Fort Lauderdale, Florida, said.

"The threshold for (corals) could be approached by the middle of this century ... when they'll reach a point where they may no longer be able to reproduce themselves as fast as they're being destroyed," said Chris Langdon, am associate professor at the University of Miami's Rosenstiel School of Marine and Atmospheric Science.

"It's not going to be instant. They're not going to disappear that year. It may take another 50 or 100 years."

It was only recently that scientists woke up to the fact that global warming would reduce the pH value of the oceans due to a chemical reaction of water with CO2. The pH scale is a measure of alkalinity or acidity, with 7 being neutral.

The pH value of the oceans has been around 8.2 for hundreds of thousands of years, but since the start of the industrial age in 1800, it has dropped by 0.1.

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