Oceans home to 80% of all life — plankton provide 50 percent of the oxygen we breathe

By Stephen Leahy

DURBAN, South Africa, Dec 3 (IPS)

The world’s oceans are becoming hot, sour and breathless – threatening a vital source of food for a billion people mainly in the developing world experts warned today at a special Oceans Day event at the UN climate negotiation.

Oceans are home 80 percent of all life on the planet and emissions from fossil fuels are turning them increasingly acidic, raising water temperatures and reducing the amount of oxygen in some regions said oceanographer Carol Turley from Plymouth Marine Laboratory in the UK.

“We don’t know what all the consequences will be. We suspect the combination of all three will be far worse than one alone,” Turley told IPS in an interview on the sidelines of climate treaty negotiations known as COP 17.

It was only a few years ago that researchers realised that human emissions of carbon dioxide (CO2) was making the surface waters of oceans more acidic. The oceans naturally absorb CO2 from the atmosphere and have now absorbed about a third of all human emissions. That has kept the climate from warming faster but the additional carbon is altering the oceans’ chemistry making them 30 percent more acidic.

One documented impact is that shell-forming creatures like plankton produce thinner shells in more acidic ocean waters. These species are often very important parts of the marine food chain. As emissions of CO2 into the atmosphere increase the more the ocean sours.

[See a powerful 11 min film on Ocean acidification]

In less than ten years at least 10 per cent of the Arctic Ocean surface waters will be too acid for shell-forming species like plankton. By 2040 most of the Arctic Ocean will be too acidic as will significant areas of the Antarctic Ocean said Turley.

The cold waters of the polar regions allow more CO2 to be absorbed faster. The oceans haven’t seen a rapid change like this in 60 million years, she explained.

“But there will also be strange impacts. New research is showing changes in growth, behaviour and reproduction in a variety of non-shell forming species.”

Estuaries and ocean upwelling zones that are often important fishing grounds are also regions where acidification is fastest. Those areas are also subject to low oxygen levels and increasing temperatures creating new conditions in the oceans that no marine species has ever had to cope with.

Oceans are also absorbing most of the extra heat trapped by the additional CO2 in the atmosphere. Again, without this land temperatures would far higher and extreme weather events far worse.

“There is some evidence that some crab species cannot tolerate higher temperatures when ocean is more acidic,” she said.

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