Greenhouse effect makes acid sinks of world's oceans

California : Far from Copenhagen's turbulent climate talks, the sea lions, harbour seals and sea otters reposing along the shoreline and kelp forests of California's Monterey Bay National Marine Sanctuary stand to gain from any global deal to cut greenhouse gases.

These foragers of the protected marine area's frigid waters, flipping in and out of sight of kayakers, may not seem like obvious beneficiaries of a climate treaty crafted in the Danish capital. But reducing carbon emissions worldwide also would help mend a lesser-known environmental problem: ocean acidification.

"We're having a change in water chemistry, so 20 years from now the system we're looking at could be affected dramatically but we're not really sure how. So we see a train wreck coming," said Andrew DeVogelaere, the sanctuary's research director.

Nothing in the treaty negotiations specifically addresses the effects of carbon absorption in the oceans on marine life, which studies show is damaging key creatures' hard shells or skeletons.

Oceans absorb about 25 per cent of the world's greenhouse gases pumped into the atmosphere from human activities each year, says a new UN report released at the Copenhagen talks this week. That helps slow global warming in the atmosphere, the focus of the Copenhagen talks.

But carbon dissolving in oceans also forms carbonic acid, raising waters' acidity that damages all manner of hard-shelled creatures, and setting off a chain reaction that threatens the food chain supporting marine life, including the lumbering sea mammals along the 276-mile coast of the California sanctuary and the rest of the US West Coast.

Ocean acidity could increase 150 per cent just by mid-century, according to the report by the Secretariat of the UN Convention on Biological Diversity.

"This dramatic increase is 100 times faster than any change in acidity experienced in the marine environment over the last 20 million years, giving little time for evolutionary adaptation within biological systems," it said.

The average acidity of oceans' surface water is estimated to increase measurably by the end of the century and will affect marine life, according to Peter Brewer, a senior scientist at the Monterey Bay Aquarium Research Institute.

"The total quantity of carbon dioxide that we've put into the oceans today is around 530 billion tonnes," Brewer told journalists on a fall fellowship programme with the Honolulu-based East-West Centre. "Now, it's going up at about 1 million tonnes an hour. You can't keep doing that without it having some impact."

And Brewer, a member of the Nobel Peace Prize-winning UN scientific panel on climate change, said that's only part of the story. "The trouble is, there's more than one thing going on," he said, citing other effects of climate change that bring, for example, "milder winters, so the deep ocean is getting less oxygen down there."