Acid oceans warning( The worlds oceans are becoming more ...)

The worlds oceans are becoming more acid, with potentially devastating consequences for corals and the marine organisms that build reefs and provide much of the Earths 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 planets marine life.

Acid oceans will be among the issues explored by Australias 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. Theres not much debate about how it happens: put more CO₂ into the air above and it dissolves into the oceans.