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Last Updated: Tuesday, 17 August, 2004, 08:49 GMT 09:49 UK
Probe into rising ocean acidity
Ocean, BBC
Ocean acidity is gradually on the rise
The UK's Royal Society has launched an investigation into the rising acidity of the world's oceans due to pollution from the greenhouse gas carbon dioxide.

The change could have catastrophic consequences for marine life.

Oceans mop up carbon dioxide from the atmosphere, lowering the water's pH value - an effect that may be exacerbated by burning of fossil fuels.

Scientists on the working group are due to publish an initial report into the phenomenon by early next year.

The same pollution that we believe is heating the world's oceans...is also altering their chemical balance
Professor John Raven
The investigation by the Royal Society, the UK national academy of science, will probe the potential impact of this rising ocean acidity on marine life - which at present is largely unknown.

Increasing use of fossil fuels means more carbon dioxide is going into the air. Most of it will eventually be absorbed by seawater, where it reacts to form carbonic acid.

The Intergovernmental Oceanographic Commission reports that some 20-25 million tonnes of carbon dioxide are being added to the oceans each day.

Researchers believe such dramatic changes in the carbon dioxide system in surface waters have not been observed for more than 20 million years of Earth history.

Delicate balance

Experts currently predict that if this trend continues, ocean pH could fall by as much as 0.4 units by the year 2100.

"The thing about acidification is that it is happening at the same time that the oceans are warming, so organisms are going to have to deal with two major changes," working group member Dr Carol Turley of Plymouth Marine Laboratory told BBC News Online.

"Whether they balance each other, or whether they double or triple up is not known."

Coral reef, AP
Increasing acidity could accelerate the disappearance of coral reefs
Scientists fear this increasing acidification could have a particularly detrimental effect on corals and sea creatures with hard shells.

Increasing acidity reduces the availability of calcium carbonate from the water - which the creatures rely on to produce their hard skeletons. Juvenile organisms could be most susceptible to these changes.

Acidification may also directly affect the growth and reproduction rates of fish, as well as affecting the plankton populations which they rely on for food, with potentially disastrous consequences for marine food webs.

In addition, nutrient concentrations in surface waters of high-latitude regions are likely to fall, subsurface waters become less oxygenated, and phytoplankton will experience increased exposure to sunlight.

This could affect multiple marine species and change the composition of biological communities in ways that are not yet understood.

Gephyrocapsa Oceanica
Some phytoplankton struggle to grow shells at high CO2 levels
According to research by Christopher Sabine of the US National Oceanographic and Atmospheric Administration (NOAA) the ocean has taken up approximately 120 billion metric tonnes of carbon generated by human activities since 1800.

"The same pollution that we believe is heating the world's oceans through global warming is also altering their chemical balance," Professor John Raven, chair of the working group, said.

"This study will look at what impact increased acidity levels might have on marine life and re-emphasise the urgent need to respond to the spectre of climate change, an issue identified by the UK Government as a priority for its Presidency of G8 in 2005."

The issue was highlighted last year with a research paper published in the prestigious journal Nature by Ken Caldeira and Michael Wickett of the Lawrence Livermore National Laboratory in California, US. Dr Caldeira is also a member of the Royal Society working group.




SEE ALSO:
Oceans becoming more acidic
24 Sep 03  |  Science/Nature
Ocean medicines could be lost
13 May 04  |  Science/Nature
Sea 'dead zones' threaten fish
29 Mar 04  |  Science/Nature


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