Human carbon emissions make oceans corrosive - study

By Deborah Zabarenko, Environment Correspondent

WASHINGTON (Reuters) - Carbon dioxide spewed by human activities has made ocean water so acidic that it is eating away at the shells and skeletons of starfish, coral, clams and other sea creatures, scientists said on Thursday.

Marine researchers knew that ocean acidification, as it's called, was occurring in deep water far from land. What they called "truly astonishing" was the appearance of this damaging phenomenon on the Pacific North American continental shelf, stretching from Mexico to Canada.

"This means that ocean acidification may be seriously impacting our marine life on our continental shelf right now, today," said Richard Feely of the Pacific Marine Environmental Laboratory, part of the U.S. National Oceanic and Atmospheric Administration.

Other continental shelf regions around the world are likely to face the same fate, he said.

Plenty of natural activities, including human breath, send the greenhouse gas carbon dioxide into the atmosphere, but for the last 200 years or so, industrial processes that involve the burning of fossil fuels such as coal and petroleum have pushed emissions higher.

Oceans have long been repositories for the carbon dioxide, absorbing some 525 billion tonnes of the climate-warming substance over the last two centuries -- about one-third of all human-generated carbon dioxide for that period.

But the daily absorption of 22 million tonnes of the stuff has changed the chemistry and biology of the oceans, turning it corrosive and making it difficult or impossible for some animals to produce their calcium carbonate shells and skeletons, the researchers said.