Oceans choking on CO2, face deadly changes: study

Michael Perry, Reuters 18 Jun 10;

SYDNEY (Reuters) - The world's oceans are virtually choking on rising greenhouse gases, destroying marine ecosystems and breaking down the food chain -- irreversible changes that have not occurred for several million years, a new study says.

The changes could have dire consequences for hundreds of millions of people around the globe who rely on oceans for their livelihoods.

"It's as if the Earth has been smoking two packs of cigarettes a day", said the report's lead-author Australian marine scientist Professor Ove Hoegh-Guldberg.

The Australia-U.S. report published in Science magazine on Friday, studied 10 years of marine research and found that climate change was causing major declines in marine ecosystems.

Oceans were rapidly warming and acidifying, water circulation was being altered and dead zones within the ocean depths were expanding, said the report.

There has also been a decline in major ocean ecosystems like kelp forests and coral reefs and the marine food chain was breaking down, with fewer and smaller fish and more frequent diseases and pests among marine organisms.

"If we continue down this pathway we get into conditions which have no analog to anything we've experienced," said Hoegh-Guldberg, director of the Global Change Institute at The University of Queensland.

Hoegh-Guldberg said oceans were the Earth's "heart and lungs", producing half of the world's oxygen and absorbing 30 percent of man-made carbon dioxide.

"We are entering a period in which the very ocean services upon which humanity depends are undergoing massive change and in some cases beginning to fail," said Hoegh-Guldberg.

"Quite plainly, the Earth cannot do without its ocean. This is further evidence that we are well on the way to the next great extinction event."

More than 3.5 billion people depend on the ocean for their primary source of food and in 20 years this number could double, the report's authors say.

The world's climate has remained stable for several thousand years, but climate change in the past 150 years is now forcing organisms to change rapidly -- changes that through evolution would normally take a long time, said the report.

"We are becoming increasingly certain that the world's marine ecosystems are approaching tipping points. These tipping points are where change accelerates and causes unrelated impacts on other systems," said co-author marine scientist John F. Bruno at the University of North Carolina.

Last week, the head of the United Nations Environment Program, Achim Steiner, said it was crucial the world responded to the loss of coral reefs, forests and other ecosystems "that generate multi-trillion dollar services that underpin all life-including economic life-on Earth".

(Reporting by Michael Perry; Editing by David Fogarty)

Ocean changes may have dire impact on people
Global Change Institute, EurekAlert 17 Jun 10

The first comprehensive synthesis on the effects of climate change on the world's oceans has found they are now changing at a rate not seen for several million years.

In an article published today in Science magazine, scientists reveal the growing atmospheric concentrations of man-made greenhouse gases are driving irreversible and dramatic changes to the way the ocean functions, with potentially dire impacts for hundreds of millions of people across the planet.

The findings of the report, "The impact of climate change on the world's marine ecosystems" emerged from a synthesis of recent research on the world's oceans, carried out by two of the world's leading marine scientists, one from The University of Queensland in Australia, and one from The University of North Carolina at Chapel Hill, in the USA.

Professor Ove Hoegh-Guldberg, lead author of the report and Director of The University of Queensland's Global Change Institute, says the findings have enormous implications for mankind, particularly if the trend continues.

He said that the Earth's ocean, which produces half of the oxygen we breathe and absorbs 30% of human-generated CO2, is equivalent to its heart and lungs. "Quite plainly, the Earth cannot do without its ocean. This study, however, shows worrying signs of ill health.

"It's as if the Earth has been smoking two packs of cigarettes a day!"

He went on to say, "We are entering a period in which the very ocean services upon which humanity depends are undergoing massive change and in some cases beginning to fail", says Prof. Hoegh-Guldberg. "Further degradation will continue to create enormous challenges and costs for societies worldwide."

He warned that we may soon see "sudden, unexpected changes that have serious ramifications for the overall well-being of humans," including the capacity of the planet to support people. "This is further evidence that we are well on the way to the next great extinction event."

The "fundamental and comprehensive" changes to marine life identified in the report include rapidly warming and acidifying oceans, changes in water circulation and expansion of dead zones within the ocean depths.

These are driving major changes in marine ecosystems: less abundant coral reefs, sea grasses and mangroves (important fish nurseries); fewer, smaller fish; a breakdown in food chains; changes in the distribution of marine life; and more frequent diseases and pests among marine organisms.

Report co-author, Dr John F. Bruno, an Associate Professor at The University of North Carolina, says greenhouse gas emissions are modifying many physical and geochemical aspects of the planet's oceans, in ways "unprecedented in nearly a million years". "This is causing fundamental and comprehensive changes to the way marine ecosystems function," Dr Bruno said.

"We are becoming increasingly certain that the world's marine ecosystems are approaching tipping points. These tipping points are where change accelerates and causes unrelated impacts on other systems, the results of which we really have no power or model to foresee."

The authors conclude: "These challenges underscore the urgency with which world leaders must act to limit further growth of greenhouse gases and thereby reduce the risk of these events occurring. Ignoring the science is not an option."

In their study, the researchers sought to address a gap in previous studies that have often overlooked the affects of climate change on marine ecosystems, due to the fact that they are complex and can be logistically difficult to study.

According to leading US marine scientist, the University of Maine's School of Marine Services Professor Robert S. Steneck, the study provides a valuable indicator of the ecological risk posed by climate change, particularly to coastal regions.

"While past studies have largely focused on single global threats such as 'global warming', Hoegh-Guldberg and Bruno make a compelling case for the cumulative impacts of multiple planet-scale threats," Prof. Steneck said.

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Images: http://gci.uq.edu.au/ScienceJune2010