Seas turn to acid as they absorb global pollution

The world's oceans are sacrificing themselves to try to stave off global warming, a major international research programme has discovered.

The world's oceans are sacrificing themselves to try to stave off global warming, a major international research programme has discovered.

Their waters have absorbed about half of the carbon dioxide emitted by human activities over the past two centuries, the 15-year study has found. Without this moderating effect, climate change would have been much more rapid and severe.

But in the process the seas have become more acid, threatening their very life. The research warns that this could kill off their coral reefs, shellfish and plankton, on which all marine life depends.

News of the alarming conclusions of the research - headed by US government scientists - follows the discovery, reported in Friday's Independent, of a catastrophic failure of North Sea birds to breed this summer, thought to be the result of global warming.

The disaster - forecast in The Independent on Sunday last October - appears to have been caused by plankton moving hundreds of miles to the north to escape from an unprecedented warming on the sea's waters. Sand eels - millions of which normally provide the staple diet of many seabirds and large fish - have disappeared, because they, in turn, depend on the plankton.

The new study warns of an even more alarming collapse throughout the world's oceans if climate change continues. It is the result of a mammoth research effort, which has taken and analysed 72,000 samples of seawater from 10,000 different places in the oceans since 1989.

Led by scientists working for the US National Oceanic and Atmospheric Administration in Seattle, it has also involved teams of researchers from Australia, Canada, Spain, Japan, South Korea and Germany.

It has discovered, for the first time, that the seas and oceans have soaked up almost half of all human emissions of carbon dioxide, the main cause of global warming, since the start of the Industrial Revolution.

By doing so they have greatly slowed climate change, and almost certainly prevented it from already causing catastrophe.

"The oceans are performing this tremendous service to humankind by reducing the amount of carbon dioxide in the atmosphere," says Dr Christopher Sabine, one of the leaders of the research. But, he adds, this is coming at a great cost because the act of salvage "is changing the chemistry of the oceans".

The research concludes that "dramatic changes", such as have not occurred for at least 20 million years, now appear to be under way. They could have "significant impacts on the biological systems of the oceans in ways that we are only beginning to understand".

As the water naturally absorbs carbon dioxide from the air, it forms carbonic acid. And the acid then mops up calcium carbonate, a substance normally plentiful in the oceans that sea creatures use to make the protective shells that they need to survive.

The scientists say that if the world goes on producing more and more carbon dioxide, this shell formation will become increasingly difficult, while the world will heat up anyway.

The results are incalculable, because so may shelled creatures live in the seas, ranging from clams and corals to the plankton and other tiny creatures that form the base of the entire food chain of the oceans.

The surface waters and upper 10 per cent of the oceans - which contain most of the life - are the most acidic, the research shows. The acidity also varies around the world. The North Atlantic - the nearest ocean to the world's most polluting countries, is the most affected; the southern ocean that encircles Antarctica the least.

When the scientists took a species of snail from the relatively unpolluted waters of the far north of the Pacific, near the Arctic Circle, and put it in seawater with carbon dioxide levels similar to those found elsewhere, the animals' shells began to dissolve.

Dr Peter Brewer, of the Monterey Bay Aquarium Research Institute - who was not himself involved in the research - calls the results "a wake-up call". He adds: "The numbers are crystal clear. The analysis is impeccable. There is no uncertainty about this. These impacts of a high carbon dioxide ocean are real, and are measurable today."

The research also explodes a heavily touted "solution" to global warming. Critics of international action, including members of the Bush administration, say that there is little need to curb carbon dioxide emissions because the gas could be collected and injected into the oceans for disposal. However, the study shows that this cure could be even worse than the disease.

A Sea Song

By Martin Newell, 'IoS' Poet in Residence

The sand eel goes without his tea
Because of human industry
So guillemots are starving
And the puffin's eating nothing
The kittiwake and skua
May not grow to be mature
And the sea's got indigestion now

Chorus
Must I go down to the sea again?
To the lonely sea in tears
The sky is strangely empty
And the silence hurts my ears

Now the arctic tern - the mother
Thinks a tern deserves another
But she ain't disposed to breeding
With her troubles over feeding
The ocean still is heaving
But the creatures are all leaving
And the sea's got indigestion now

See, there isn't any potion
You can give a gippy ocean
Like a Gaviston or Rennie
And we ain't come up with any
Since the businesses we banked on
Have been murdering the plankton
So the sea's got indigestion now

The day before the siren went
We thought about environment
We talked about restrictions
And made various predictions
But market forces beckoned
So the oceans all came second
And the sea's got indigestion now.