New climate change signal: oceans turning acidic

“Some organisms were very sensitive,” Anne Cohen, a researcher at WHOI who took part in the study, said. "But there were a couple that didn’t respond to CO2 or didn’t respond till it was sky-high – about 2,800 parts per million. We’re not expecting to see that anytime soon.” One of the seven stoics was coral.

The team cautions that the animals were well fed and were not subject to any other environmental stresses. So the results don't shed much light on the synergystic effects acidification might have on the seven survivors. That's for another round of experiments. Still, “we can’t assume that elevated CO2 causes a proportionate decline in calcification of all calcifying organisms,” says Cohen.

No complex computer models here

The science behind the ocean acidification process is far more straightforward than climate science – needing little more than a high-school grasp of chemistry to understand, says Richard Feeley, a researchers at NOAA's Pacific Marine Environmental Laboratory in Seattle, Wash.

He says that the oceans are soaking up CO2 at a rate that matches the rate at which atmospheric CO2 concentrations are rising. The link between rising human emissions and rising uptake is unequivocal, he says, adding that the ocean is growing acidic at a pace 100 times faster than at any time in at least 20 million years. And no matter which ocean researchers examine, "we get the same changes everywhere we look," he says.

While the basic mechanism is easy to grasp, scientists are finding it more difficult to determine the long-term biological effects. Much depends on the animals involved, as well as natural cycles of ocean circulation that bring carbonate-poor waters to the surface.

Scientists in Australia, for instance, have projected that rising acidity may start eating into populations of tiny plankton in the Southern Ocean far sooner than previously believed. The reason: natural upwellings of carbonate-poor water combines with acidification to deprive the creatures of carbonates at a critical time in their development. They had adapted to deal with upwelling part of the equation. But they are unprepared to handle the additional reduction in carbonate caused by the industrial CO2 being added to the oceans.

Others have found evidence of shellfish losing their ability to grip rocks in increasingly acidic waters, as well as signs of shell erosion.

Filmmaker Sven Husbey, who along with his wife produced a documentary on the subject, says that as they've toured the world showing the film they have won converts. Many of the viewers are self-described skeptics about global warming. Yet "again and again and again, they get ocean acidification," he says. "Even if we could cope with global warming without reducing emissions, we would still lose the oceans."

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