Rising ocean acidity provides watertight argument for cutting carbon emissions

Just in time for the G8 jamboree British scientists have released a new report resurrecting concerns about the other disastrous effect of greenhouse gases.

Using science so simple even George Bush could not argue with it, experts at the Royal Society have published a thorough report outlining how carbon dioxide that can be traced back to industry is gradually changing the chemical make-up of the world's oceans, slowly but surely turning them acidic.

The change is already harming marine life sensitive to the pH of the water around it including corals, shellfish, sea urchins and star fish.

The report, published on Thursday, June 30, concludes that the only way to undo the damage is to cut emissions of carbon dioxide.

Cynics will say the core message of the document is hardly a revelation as most of what it says has been in the public domain for several years (see related story).

But its timely release offered the Bush administration a get-out clause which would have allowed it to accept the need to cut emissions without accepting the science of climate change.

Professor John Raven, chair of the Royal Society working group on ocean acidification said: "Along with climate change, the rising acidity of our oceans is yet another reason for us to be concerned about the carbon dioxide we are pumping into the atmosphere.

"Our world leaders meeting at next week's G8 summit must commit to taking decisive and significant action to cut carbon dioxide emissions.

"Failure to do so may mean that there is no place in the oceans of the future for many of the species and ecosystems that we know today."

According to the report, ocean acidification due to increasing atmospheric carbon dioxide, excess carbon dioxide in the atmosphere, from man's burning of fossil fuels, has already increased the acidity of the world's oceans to a level that is irreversible in our life times.

This is because the oceans act as a sponge, taking up carbon dioxide from the atmosphere which dissolves and forms an acid in the seawater.

Sea creatures such as corals, shell fish, sea urchins and star fish are likely to suffer the most because higher levels of acidity makes it difficult for them to form and maintain their hard calcium carbonate skeletons and shells.

For example, even under the more optimistic predictions for future carbon dioxide emissions into the atmosphere, the combined effects of climate change and ocean acidification mean that corals could be rare on tropical and subtropical reefs, such as the Great Barrier Reef, by 2050.

This will have major ramifications for hundreds of thousands of other species that dwell in the reefs as well as for the people that depend upon them, both for food and to help to protect coastal areas from oceanic phenomenon such as tsunamis.

The report says that changes in ocean chemistry, caused by ocean acidification, means that we can predict that some creatures in the Antarctic Ocean will be among the first to be affected.

For example, some types of plankton a major source of food for fish and other animals may be unable to make their calcium carbonate shells by 2100. This may have significant consequences for entire food webs in the region, although the overall impact of this is unclear.

Higher concentrations of carbon dioxide may also make it harder for some larger marine animals to obtain oxygen from seawater.

Squid, for example, are particularly sensitive because they move by energy-demanding jet propulsion which needs a good supply of oxygen.

Professor Raven said: "Basic chemistry leaves us in little doubt that our burning of fossil fuels is changing the acidity of our oceans.

"And the rate change we are seeing to the ocean's chemistry is a hundred times faster than has happened for millions of years.

"We just do not know whether marine life which is already under threat from climate change can adapt to these changes."

By absorbing carbon dioxide the oceans actually help stave off climate change.

Since the start of the industrial revolution the oceans have absorbed about half of the carbon dioxide produced by humans.

They are currently taking up one tonne of this carbon dioxide for each person on the planet every year.

However, the report warns that rising levels of acidity in the ocean may mean that the ability of the oceans to mop up carbon dioxide from the atmosphere will be reduced as the surface waters approach saturation point.

Professor Raven said: "The oceans play a vital role in the earth's climate and other natural systems which are all interconnected.

"By blindly meddling with one part of this complex mechanism, we run the risk of unwittingly triggering far reaching effects."

By Sam Bond


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