The cumulative impact of "severe individual stresses," ranging from climate warming and sea-water acidification to widespread chemical pollution and over-fishing, would threaten the marine environment with a catastrophe "unprecedented in human history."
The conclusions were published by a panel of international scientists who reviewed recent research at a workshop at Oxford University in Britain. They will be presented to the United Nations in New York later this week for discussions on reforming governance of the oceans.
The report warned that damage to marine life would harm its ability to support humans and that entire ecosystems, such as coral reefs, could be lost in a generation.
"Unless action is taken now, the consequences of our activities are at a high risk of causing, through the combined effects of climate change, over-exploitation, pollution and habitat loss, the next globally significant extinction event in the ocean," it said.
The marine scientists 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.
"The findings are shocking," said Alex Rogers, the scientific director of the International Programme on the State of the Ocean, which convened the panel with the International Union for Conservation of Nature.
"As we considered the cumulative effect of what humankind does to the ocean, the implications became far worse than we had individually realized. This is a very serious situation demanding unequivocal action at every level."
"The world's leading experts on oceans are surprised by the rate and magnitude of changes we are seeing," said Dan Laffoley, the co-author of the report.
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