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Major
international study warns global warming is destroying coral reefs and calls for
'drastic actions'
December 13, 2007 Cornell University By Susan Lang
If world leaders do not immediately engage in a race against time to save the
Earth's coral reefs, these vital ecosystems will not survive the global warming
and acidification predicted for later this century. That is the conclusion of a
group of marine scientists from around the world in a major new study published
in the journal Science on Dec. 13.
It's vital that the public
understands that the lack of sustainability in the world's carbon emissions is
causing the rapid loss of coral reefs, the world's most biodiverse marine
ecosystem," said Drew Harvell, Cornell professor of ecology and
evolutionary biology and head of the Coral Disease Research Team, which is part
of the international Coral Reef Targeted Research (CRTR) group that wrote the
new study.
The rise of carbon dioxide
emissions and the resultant climate warming from the burning of fossil fuels are
making oceans warmer and more acidic, said co-author Harvell, which is
triggering widespread coral disease and stifling coral growth toward "a
tipping point for functional collapse."
The 17 marine scientists who
authored the new study argue that "drastic action" is needed from
world leaders to turn around the trend in rising levels of atmospheric carbon
dioxide (CO2) to protect coral reefs. They based their conclusions on the
forecasts for rising global temperatures and levels of CO2 announced recently by
the Intergovernmental Panel on Climate Change, a United Nations body.
"Coral reefs have already
taken a big hit from recent warm temperatures, but rapid rises in carbon dioxide
cause acidification, which adds a new threat: the inability of corals to create
calcareous skeletons," said Harvell. "Acidification actually threatens
all marine animals and plants with calcareous skeletons, including corals,
snails, clams and crabs. Our study shows that levels of CO2 could become
unsustainable for coral reefs in as little as five decades."
Pictured at left is
the typical coral reef today on the southern Great Barrier Reef, which has
endured a rise of 1 degree C and 375 parts per million of atmospheric carbon
dioxide concentration. The middle frame shows what a reef would look like if
global temperatures rise one more degree and CO2 concentrations increase, as
predicted. The right frame shows what a reef would like if temperatures and CO2
levels rise even more.
In the short term, better
management of overfishing and local stressors may increase resilience of reefs
to climate threats, but rising global CO2 emissions will rapidly outstrip the
capacity of local coastal managers and policy-makers to maintain the health of
these critical ecosystems if the emissions continue unchecked, the authors
stress.
At stake, added Ove
Hoegh-Guldberg, director of the Center for Marine Studies at the University of
Queensland, Australia, and the study's senior author, are ecosystems that play
vital roles in providing habitats for a vast array of marine species that are
essential to the oceans' complex food chain. They also provide livelihoods to
100 million people who live along the coasts of tropical developing countries.
Diving tourism in the Caribbean alone is estimated to generate more than $100
billion a year. The loss of coral reef ecosystems also is exposing people to
flooding, coastal erosion and the loss of food and income from reef-based
fisheries and tourism, he added.
The CRTR is a leading
international coral reef research initiative that provides a coordinated
approach to credible, factual and scientifically proven knowledge for improved
coral reef management. It is a partnership of the Global Environment Facility,
the World Bank, the University of Queensland, Australia, the U.S. National
Oceanic and Atmospheric Administration and approximately 40 research institutes
and other third parties around the world.
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