At 450 PPM CO2, World Oceans' Chemistry Would Make Coral Rebuilding Possible In Maybe 10% Of Reefs

[hatrack]

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Ocean acidification could devastate coral reefs and other marine ecosystems even if atmospheric carbon dioxide stabilizes at 450 ppm, a level well below that of many climate change forecasts, report chemical oceanographers Long Cao and Ken Caldeira of the Carnegie Institution's Department of Global Ecology in the journal Geophysical Research Letters. The researchers' conclusions are based on computer simulations of ocean chemistry stabilized at atmospheric CO2 levels ranging from 280 parts per million (pre-industrial levels) to 2000 ppm. Present levels are 380 ppm and rapidly rising due to accelerating emissions from human activities, primarily the burning of fossil fuels.

This study was initiated as a result of Caldeira's testimony before a Congressional subcommittee on Fisheries, Wildlife and Oceans in April of 2007. At that time he was asked what stabilization level would be needed to preserve the marine environment, but had to answer that no such study had yet addressed that question. Cao and Caldeira's study helps fill the gap.

Atmospheric CO2 absorbed by the oceans' surface water produces carbonic acid, the same acid that gives soft drinks their fizz, making certain carbonate minerals dissolve more readily in seawater. This is especially true for aragonite, the mineral used by corals and many other marine organisms to grow their skeletons. For corals to be able to build reefs, which requires rapid growth and strong skeletons, the surrounding water needs to be highly supersaturated with aragonite. "Before the industrial revolution, over 98% of warm water coral reefs were surrounded by open ocean waters at least 3.5 times supersaturated with aragonite" says Cao. "But even if atmospheric CO2 stabilizes at the current level of 380 ppm, fewer than half of existing coral reef will remain in such an environment. If the levels stabilize at 450 ppm, fewer than 10% of reefs would be in waters with the kind of chemistry that has sustained coral reefs in the past."

For the ecologically productive cold waters near the poles, the prospects are equally grim, says Cao. "At atmospheric CO2 levels as low as 450 ppm, large parts of the Southern Ocean, the Arctic Ocean, and the North Pacific would experience a rise in acidity that would violate US Environmental Protection Agency water quality standards." Under those conditions the shells of many marine organisms would dissolve, including those at the base of the food chain.

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http://www.terradaily.com/reports/Modest_CO2_Cutbacks_May_Be_Too_Little_Too_Late_For_Coral_Reefs_999.html

[Barrett808]

1. And if the carbonate platforms die, children, that's one big carbon sink gone

We must save the corals. And the oceans.

[GliderGuider]

2. Well, at least we won't have to worry about nasty fish bones any more

One of the other effects of ocean acidification is the inability of fish to form bones...

[hatrack]

3. So, when the package says "Ocean-Fresh Filets", it won't just be advertising copy!

Cool!