Acidic seawater found along Pacific Coast
SEATTLE – Acidic water is appearing along the Pacific Coast decades earlier than expected, apparently the result of climate change as carbon dioxide turns the ocean more corrosive, scientists have reported.
In surveys from Vancouver Island in Canada to the tip of Baja California in Mexico, scientists reported finding the first evidence of acidic sea water in large quantities along the continental shelf, the shallow zone where most marine creatures live.
In some areas the water was corrosive enough to dissolve the shells of clams, coral and tiny creatures that are crucial to the food chain.
“Entire marine ecosystems are likely to be affected,” said co-author Debby Ianson, a Fisheries and Oceans Canada oceanographer at Sidney, British Columbia.
The research, led by the National Oceanic and Atmospheric Administration’s Pacific Marine Environmental Laboratory in Seattle and involving experts from Oregon, California and Canada, was reported Thursday in Science Express, the online edition of the journal Science.
“I think this is a red flag for us because it’s right at our doorstep on the West Coast,” said Victoria J. Fabry, a biological oceanographer at California State University, San Marcos, who was not involved with the study. “It’s telling us that we really need more monitoring to figure out what’s going on.”
Off Northern California, acidified water was found four miles from shore.
“What we found … was truly astonishing,” said Richard A. Feely, an oceanographer at the NOAA lab. “This means ocean acidification may be seriously impacting marine life on the continental shelf right now.”
Acidification of oceans results from the same increase in carbon dioxide in the air that has been blamed for raising temperatures worldwide.
When saltwater, normally slightly alkaline, absorbs more airborne carbon dioxide, the result is an increase in carbonic acid and a decrease in carbonate, which is critical to the formation of calcium carbonate shells by clams, oysters and other marine life.
The water is not acidic enough to threaten human health directly. “We’re not talking battery acid here,” said co-author Burke Hales, an oceanographer at Oregon State University.
Feely estimates oceans have absorbed 525 billion tons of carbon dioxide since the Industrial Revolution, blunting to some extent the rise of temperatures worldwide but causing an increase of more than 30 percent in acidity.
Feely and an NOAA colleague, Christopher L. Sabine, previously showed that areas of acidified water have been growing and moving closer to the surface.
Until now, scientists believed the most acidified water was in the ocean depths because cold water is naturally high in carbon dioxide, which is a byproduct of the decay of plankton, and can hold more of that greenhouse gas. Climate models to date indicated the levels of acidic water now found closer to shore would not occur until the end of the 21st century.
“This is another example where what’s happening in the natural world seems to be happening much faster than what our climate models predict,” said Ken Caldeira, a climate scientist in the Carnegie Institution at Stanford University.
“This is a startling result,” said Edward L. Miles, a professor with the University of Washington’s Climate Impacts Group and School of Marine Affairs who was not involved in the study. “It means the global community needs to pay much more attention to documenting what is going on in the global coastal ocean as well.”