Acid seas huge threat to coral reefs: study|
By Jim Loney
Thu Dec 13, 2007 7:31pm EST
MIAMI (Reuters) - In less than 50 years, oceans may be too acidic for coral
reefs to grow because of carbon emissions from the burning of fossil fuels by
humans, according to research released on Thursday.
And unless still rising carbon dioxide emissions fall in the near future,
existing reefs could all be dying by 2100, scientists said.
Australia's Great Barrier Reef, the world's largest coral expanse, and
Caribbean reefs will be among the first casualties, according to the scientists
who worked on a major coral project worldwide.
The study, to be published in Friday's issue of the journal Science, should
serve as a warning to delegates to a U.N. climate conference in Bali, Indonesia,
this week, the researchers said.
"We need rapid reductions in carbon dioxide levels," said Ove Hoegh-Guldberg,
a marine science professor at Australia's University of Queensland and a lead
author of the study.
"The impact of climate change on coral reefs is much closer than we
appreciated," he said in a telephone interview from Australia. "It's just around
The study found emissions of carbon dioxide, the main "greenhouse" gas
contributing to global warming, are boosting acidity so much that sea water
covering 98 percent of all coral reefs may be too acidic by 2050 for some corals
to live, and while others may survive they would be unable to build reefs.
"Unless we take action soon there is a real possibility that coral reefs, and
everything that depends on them, will not survive this century," researcher Ken
Coral reefs, delicate undersea structures resembling rocky gardens that are
made by tiny animals called coral polyps, are important nurseries and shelters
for fish and other sea life.
They are also considered valuable protection for coastlines from high
Reefs are a critical source of food for millions of people and are important
for tourism from Australia to the islands of the Caribbean and the Florida Keys.
They produce $375 billion a year in economic value worldwide, according to
The Nature Conservancy environmental group, and are considered a storehouse of
potential 21st century medicines for cancer and other diseases.
The polyps secrete calcium carbonate to build the stony base of the reef.
Corals grow slowly, as little as half an inch
per year and the fragile structures they create are easily damaged by ship
groundings, storms and other threats.
The researchers, who based their work on computer simulations of ocean
chemistry, said about one-third of carbon dioxide, or CO2, put into the
atmosphere is absorbed by the ocean, slowing global warming but polluting the
The CO2 produces carbonic acid, the substance that gives soft drinks their
fizz. The acid reduces concentrations of carbonate-ions, which are critical to
Current levels of CO2 in the atmosphere are 380 parts per million,
researchers said, but rising quickly as humans increase their emissions by
burning fossil fuels.
If trends hold, the concentration could rise to 880 ppm by 2100. But even if
atmospheric CO2 stabilized at 550 ppm, which would take a concerted
international effort, no existing coral reef could survive, the researchers
"We have the world at stake here. It's a global emergency," said
Hoegh-Guldberg. "We've got to have (CO2) levels falling by 2015."
Australian and Caribbean reefs are at the greatest risk because they already
have lower carbonate-ion concentrations and therefore would "reach critical
levels sooner," he said.
The research should serve as a warning to those who look after reefs to ramp
up the fight against other threats to them, which include overfishing, pollution
from nearby land and a host of diseases, the researchers said.
"We need to think of this as the straw that broke the camel's back," said
Peter Sale of the United Nations University.
(Editing by Michael Christie and Richard Meares)
Original article: Reuters
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