By Stephen Leahy
BROOKLIN, Canada, Nov 12, 2007 (IPS)
Coral reefs face certain extinction in a few decades unless there are unprecedented reductions in carbon emissions, leading Australian scientists warn.
Corals around the world may be nothing but rubble before a child born today turns 30 years old, and almost certainly before they’re 50.
The reason? Rising carbon dioxide (CO2) levels in the atmosphere are turning the oceans acidic far faster than previously observed.
“It isn’t just the coral reefs which are affected. A large part of the plankton in the Southern Ocean, the coccolithophorids, are also affected,” said Malcolm McCulloch, an environmental research scientist at the Australian National University in Canberra.
“These (coccolithophorids) drive ocean productivity and are the base of the food web which supports krill, whales, tuna and our fisheries,” McCulloch said in a statement.
Plankton also play a vital role in removing carbon dioxide from the atmosphere and sequestering it in the deep ocean. Major declines in plankton mean atmospheric CO2 levels would rise far faster than the present forecasts and oceans would become even more acidic.
Recent research is showing that the ocean has become about one-third of a pH unit more acid over the past 50 years. This is roughly triple previous measurements.
“This is still early days for the research, and the trend is not uniform, but it certainly looks as if marine acidity is building up,” said McCulloch.
The oceans and the atmosphere are intimately connected — the quintessential yin and yang.
Changes in the atmosphere affect the oceans and vice-versa. Pump extra CO2 into the atmosphere from burning fossil fuels and some of that extra CO2 combines with carbonate ions in seawater, forming carbonic acid. The fact that CO2 is making the oceans more acid was established just three years ago. Scientists are still scrambling to determine the overall impacts.
“The effect of an acidifying ocean is that precious carbonate ions are removed,” says Ove Hoegh-Guldberg, a scientist at the Centre for Marine Studies at the University of Queensland, Australia.
“These ions are critical to the calcium carbonate production (calcification) of a range of marine organisms, including reef-building corals,” Hoegh-Guldberg told IPS.
Hoegh-Guldberg, McCulloch and more than 50 marine scientists attending a recent forum hosted by Australian Research Council Centre of Excellence for Coral Reef Studies have released a formal call to action, calling on “all societies and governments to immediately and substantially reduce greenhouse gas emissions”.
“Ocean acidification due to increased atmospheric CO2 is accelerating…Reducing CO2 emissions is the only way to prevent further damage to coral reefs,” they warn.
As carbon dioxide increases in the atmosphere, the concentration of carbonate ions declines, with the result that corals can no longer build reefs. The oceans have already absorbed nearly half of the fossil-fuel CO2 emitted into the atmosphere since pre-industrial times, causing a significant reduction in seawater pH.
“And with no reef framework, the habitat for an estimated million species is destroyed,” Hoegh-Guldberg said.
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Between a Reef and a Hard Place
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