Acid oceans warning

Oct 17, 2007

The world’s oceans are becoming more acid, with potentially devastating consequences for corals and the marine organisms that build reefs and provide much of the Earth’s breathable oxygen.

The acidity is caused by the gradual buildup of carbon dioxide (CO2) in the atmosphere, dissolving into the oceans. Scientists fear it could be lethal for animals with chalky skeletons which make up more than a third of the planet’s marine life.

Acid oceans will be among the issues explored by Australia’s leading coral scientists at a national public forum at the Shine Dome in Canberra tomorrow. The Coral Reef Futures 07 Forum is on October 18-19, 2007 and is hosted by the ARC Centre of Excellence for Coral Reef Studies (CoECRS).

“Recent research into corals using boron isotopes indicates the ocean has become about one third of a pH unit more acid over the past fifty years. This is still early days for the research, and the trend is not uniform, but it certainly looks as if marine acidity is building up,” says Professor Malcolm McCulloch of CoECRS and the Australian National University.

“It appears this acidification is now taking place over decades, rather than centuries as originally predicted. It is happening even faster in the cooler waters of the Southern Ocean than in the tropics. It is starting to look like a very serious issue.”

Corals and plankton with chalky skeletons are at the base of the marine food web. They rely on sea water saturated with calcium carbonate to form their skeletons. However, as acidity intensifies, the saturation declines, making it harder for the animals to form their skeletal structures (calcify).

“Analysis of coral cores shows a steady drop in calcification over the last 20 years,” says Professor Ove Hoegh-Guldberg of CoECRS and the University of Queensland. “There’s not much debate about how it happens: put more CO2 into the air above and it dissolves into the oceans.

“When CO2 levels in the atmosphere reach about 500 parts per million, you put calcification out of business in the oceans.” (Atmospheric CO2 levels are presently 385 ppm, up from 305 in 1960.)

“It isn’t just the coral reefs which are affected – a large part of the plankton in the Southern Ocean, the coccolithophorids, are also affected. These drive ocean productivity and are the base of the food web which supports krill, whales, tuna and our fisheries. They also play a vital role in removing carbon dioxide from the atmosphere, which could break down.”

Professor Hoegh-Guldberg said an experiment at Heron Island, in which CO2 levels were increased in the air of tanks containing corals, had showed it caused some corals to cease forming skeletons. More alarmingly, red calcareous algae – the ‘glue’ that holds the edges of coral reefs together in turbulent water – actually began to dissolve. “The risk is that this may begin to erode the Barrier of the Great Barrier Reef at a grand scale,” he says.

“As an issue it’s a bit of a sleeper. Global warming is incredibly serious, but ocean acidification could be even more so.”

Source: ARC Centre of Excellence in Coral Reef Studies

Explore further: Pact with devil? California farmers use oil firms' water

Related Stories

Artificial enzymes to reduce carbon dioxide emissions

May 19, 2015

Enzymes are biological catalysts that accelerate chemical reactions, such as the conversion of gaseous carbon dioxide (CO2) into carbonates. Carbonates are the basic component of coral reefs, mollusc shells, ...

Recommended for you

Gimmicks and technology: California learns to save water

Jul 03, 2015

Billboards and TV commercials, living room visits, guess-your-water-use booths, and awards for water stinginess—a wealthy swath of Orange County that once had one of the worst records for water conservation ...

Cities, regions call for 'robust' world climate pact

Jul 03, 2015

Thousands of cities, provinces and states from around the world urged national governments on Thursday to deliver a "robust, binding, equitable and universal" planet-saving climate pact in December.

Will climate change put mussels off the menu?

Jul 03, 2015

Climate change models predict that sea temperatures will rise significantly, including in the tropics. In these areas, rainfall is also predicted to increase, reducing the salt concentration of the surface ...

As nations dither, cities pick up climate slack

Jul 02, 2015

Their national governments hamstrung by domestic politics, stretched budgets and diplomatic inertia, many cities and provinces have taken a leading role—driven by necessity—in efforts to arrest galloping ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

luxor2
not rated yet Oct 18, 2007
What is meant here by "about one third of a pH unit more acid"? From 4.7 to 4.27? This report needs a few real data points
superhuman
not rated yet Apr 28, 2008
From wiki:
http://en.wikiped...fication
Pre-industrial (1700s) 8.179 0.000 an.field[2]
Recent past (1990s) 8.104 -0.075 field[2]

So according to the article one third of a pH unit would be from 8.179 to 8.179-0.333=7.846

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.