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ENVIRONMENT: Ailing Reefs Face New Threat of Acidity

Stephen Leahy

BROOKLIN, Canada, Jul 5 2006 (IPS) - Climate change is making the world’s oceans more acidic, seriously endangering marine ecosystems, including coral reefs.

Carbon dioxide emissions from the burning of fossil fuels have already made the oceans 30 percent more acidic than they have been in millions of years, according to a new report by leading scientists. And the rate of acidification is accelerating as the oceans absorb more than two billion tonnes of carbon each year from the atmosphere.

“This is a dramatic change in the world’s oceans, a change that marine organisms have never dealt with before,” said Joan Kleypas, the report’s lead author and a scientist at the National Centre for Atmospheric Research (NCAR) in Boulder, Colorado.

“The oceans have changed and they are becoming more acidic. There is no debate about this,” Kleypas told IPS.

Before the end of this century, the oceans may be 150 percent more acidic than they were before the era of industrialisation. That spells doom for many sea creatures, especially those that take carbonate minerals from the sea to form their skeleton shells, including coral reefs.

It is impossible to know the full impacts on fish and marine ecosystems species without further study, she said.

Experiments with tiny shell-forming species such as pteropods and coccolithophores – key food sources for many fish – reveal that they are unable to form their shells as oceans become more acid.

Other experiments show coral reefs forming much less dense skeletons, a process similar to osteoporosis in humans, said Chris Langdon of the University of Miami.

About 25 percent of all marine species spend all or part of their lives in the worlds’ reefs.

“AZT, the most important drug for HIV treatment, is derived from coral sponges,” Langdon noted.

Reefs also protect shorelines from storms and erosion while providing a source of food for many people. Their loss would mean mass migration of people inland, he said.

“This threat is hitting coral reefs at the same time that they are being hit by warming-induced mass bleaching events,” said Langdon.

Every day, the average person on the planet burns enough fossil fuel to emit 24 pounds of carbon dioxide (CO2) into the atmosphere, out of which about nine pounds is then taken up by the ocean. As this CO2 combines with seawater, it increases its acidity.

It is just like the simple children’s science experiment of adding vinegar to baking soda, which produces fizzy CO2 bubbles – except in reverse, explains Chris Sabine of the U.S. National Oceanographic and Atmospheric Administration’s Pacific Marine Environmental Laboratory (PMEL) in Seattle, Washington State.

Up until the 1800s, the CO2 in the atmosphere and the oceans were in balance, said Sabine, one of the co-authors. Since that time, humans have pumped 142 billion additional tonnes of carbon into the oceans. Had all that carbon remained in the atmosphere, global temperatures would be much higher than they are presently.

Only in the past few years have scientists studied the affects of the additional CO2 in the oceans. The report, “Impacts of Ocean Acidification on Coral Reefs and Other Marine Calcifiers,” represents a consensus summary of 50 of the world’s leading experts.

Large areas of the Pacific have already become less hospitable to shell-form organisms, says Dick Feely of PMEL. Fifteen years of ocean surveys document changes in the ocean chemistry in the North Pacific around Alaska, Feely told IPS.

“Species are being squeezed into narrower areas of the ocean,” he said.

The Arctic Ocean will be in trouble by 2050 and the entire South Pacific and much of the North Pacific will be too before the end of the century. It will take hundreds of thousands of years for the oceans to return to normal even if all CO2 emissions stopped today, said Sabine.

“But what we can do is halt the rate of increase of CO2 into the atmosphere,” he said, adding that slowing the rate at which the oceans grow more acidic may give some species time to adapt – and it may provide more time to understand what the potential impacts may be.

A major international scientific effort needs to be made now before it is too late, he stressed.

“We don’t know what the effects will be on fish eggs, larvae or non-shell forming organisms,” said Kleypas. “This is a serious issue that needs immediate attention.”