London: Scientists have warned that the world's oceans have moved into a "phase of extinction" due to human impacts such as over-fishing and climate change, and the entire ecosystem could be lost in a generation.

A preliminary report from an international panel of marine experts said that the condition of the world's seas was worsening more quickly than had been predicted; already fish stocks are collapsing, leading to a risk of rising food prices and even starvation in some parts of the world.
   
The scientists blamed the increased amount of carbon dioxide in the atmosphere for pushing up ocean temperatures, boosting algae so there is less oxygen and increasing acidity of the water, 'reported in international publication.
   
The conditions are similar to every previous mass extinction event in the Earth's history, they say.
   
Dr Alex Rogers, scientific director of International Programme on the State of the Ocean which convened a workshop at Oxford University, along with the International Union for
Conservation of Nature (IUCN), said the next generation would suffer if species are allowed to go extinct.
   
"As we considered the cumulative effect of what humankind does to the ocean the implications became far worse than we had individually realised. This is a very serious situation demanding unequivocal action at every level.
   
"We are looking at consequences for humankind that will impact in our lifetime and, worse, our children's and generations beyond that," he was quoted as saying.
   
The scientists have called for a range of urgent measures to cut carbon emissions, reduce over-fishing, shut unsustainable fisheries, create protected areas in the seas, and cut pollution.

Problems multiplying


Meanwhile the health of the world's oceans is declining much faster than originally thought under siege from pollution, overfishing and other man-made problems all at once scientists say in a new report.

The mix of interacting ingredients is in place for a mass extinction in the world's oceans, said a report by a top panel of scientists that will be presented to the United Nations on Tuesday.
   
The report says the troubles from global warming and other factors are worse when they combine with each other.

Factors include dead zones from farm run-off, an increase in acidity from too much carbon dioxide, habitat destruction and melting sea ice, along with overfishing.
   
"Things seem to be going wrong on several different levels," said Carl Lundin, director of global marine programs at the International Union for Conservation of Nature, which helped produce the report with the International Programme on the State of the Ocean. The conclusions follow an international meeting this spring in England to discuss the fate of the world's oceans.
   
Some of the changes affecting the world's seas all of which have been warned about individually in the past are happening faster than the worst case scenarios that were predicted just a few years ago, the report said.

"It was a more dire report than any of us thought because we look at our own little issues," Lundin said in an interview. "When you put them all together, it's a pretty bleak situation."

The combination of problems suggests there's a brewing worldwide die-off of species that would rival past mass extinctions, scientists said in the document. Coral deaths alone would be considered a mass extinction, according to study chief author Alex Rogers of the University of Oxford. A single bleaching event in 1998 killed one-sixth of the world's tropical coral reefs.

Lundin pointed to deaths of 1,000-year-old coral in the Indian Ocean and called it "really unprecedented."

"We now face losing marine species and entire marine ecosystems, such as coral reefs, within a single generation," the report said.
   
Carbon dioxide from the burning of coal and other fossil fuels ends up sinking in the ocean which then becomes more acidic. Warmer ocean temperatures also are shifting species from their normal habitats, Rogers said.

(Agencies)