Carbon Emissions Turning Oceans Acid, Hostile to Marine Life

LONDON, UK, July 6, 2005 (ENS) - Too much carbon in the atmosphere, emitted by humans burning fossil fuels, has already increased the acidity of the world's oceans to a level that is irreversible in our lifetimes, warns a new report published by the Royal Society, Britain's national academy of science.

The oceans are turning acid because they act as a sponge, taking up the greenhouse gas carbon dioxide from the atmosphere. The gas dissolves and forms an acid in the seawater.

Even under the predictions of low levels of carbon dioxide emissions into the atmosphere in the future, the combined effects of climate change and ocean acidification mean that by 2050 corals could be rare on tropical and subtropical reefs, such as the Great Barrier Reef, the scientists say.


Gorgonian and whip corals on Australia's Great Barrier Reef. (Photo courtesy the Great Barrier Reef Marine Park Authority)
This will affect hundreds of thousands of other species that dwell in the reefs as well as the people that depend upon them, both for food and to help to protect coastal areas from natural disasters such as tsunamis.

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."

Raven urged the G8 leaders meeting Wednesday though Friday at Gleneagles Hotel in Scotland to take "decisive and significant action to cut carbon dioxide emissions."


Professor John Raven is the Boyd-Baxter Professor of Biology at the University of Dundee in Scotland. (Photo courtesy University of Dundee)
"Failure to do so," said Raven, "may mean that there is no place in the oceans of the future for many of the species and ecosystems that we know today."

The report looks at a range of ways to tackle rising acidity such as adding limestone to the oceans to make them more alkaline. But the report concludes that cuts in emissions of carbon dioxide are the only way to stem the rising levels of acidity in the oceans and prevent potentially damaging consequences for marine life, Raven said.

Corals, shell fish, sea urchins and starfish 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.

Raven predicts that some creatures in the Antarctic Ocean will be among the first to be affected.

He says that some types of plankton may be unable to make their calcium carbonate shells by 2100. Because plankton are an important source of food for fish and other animals, entire food webs in the region may be affected, although the overall impact is as yet unclear.


Reef in the protected waters of Florida (Photo courtesy NOAA)
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," he said.

The report points out that there is still much uncertainty around the impacts of ocean acidification and recommends that a major international effort be launched into this relatively new area of research.

By absorbing carbon dioxide the oceans help limit climate change. Raven estimates the oceans are currently absorbing one metric ton of carbon dioxide for each person on the planet each year.

In the past 200 years the oceans have absorbed about half of the carbon dioxide produced by humans, he says.

But rising levels of acidity may reduce the ability of the oceans to mop up carbon dioxide from the atmosphere.

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."