Increasingly acid oceans due to CO2 'need urgent action'

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Acid oceans 'need urgent action' BBC NEWS Published: 2009/01/30 15:42:37 GMT

The world's marine ecosystems risk being severely damaged by ocean acidification unless there are dramatic cuts in CO2 emissions, warn scientists.

More than 150 top marine researchers have voiced their concerns through the "Monaco Declaration", which warns that changes in acidity are accelerating.

The declaration, supported by Prince Albert II of Monaco, builds on findings from an earlier international summit.

It says pH levels are changing 100 times faster than natural variability.

 

Based on the research priorities identified at The Ocean in a High CO2 World symposium, held in October 2008, the declaration states:

"We scientists who met in Monaco to review what is known about ocean acidification declare that we are deeply concerned by recent, rapid changes in ocean chemistry and their potential, within decades, to severely affect marine organisms, food webs, biodiversity and fisheries."

'The other CO2 problem'

It calls on policymakers to stabilise CO2 emissions "at a safe level to avoid not only dangerous climate change but also dangerous ocean acidification".

 

The researchers warn that ocean acidification, which they refer to as "the other CO2 problem", could make most regions of the ocean inhospitable to coral reefs by 2050, if atmospheric CO2 levels continue to increase.

The also say that it could lead to substantial changes in commercial fish stocks, threatening food security for millions of people.

"The chemistry is so fundamental and changes so rapid and severe that impacts on organisms appear unavoidable," said Dr James Orr, chairman of the symposium.

"The questions are now how bad will it be and how soon will it happen."

Another signatory, Patricio Bernal, executive secretary of the UN Intergovernmental Oceanographic Commission, outlined how the marine research community intended to respond to the challenge.

"We need to bring together the best scientists to share their latest research results and to set priorities for research to improve our knowledge of the processes and of the impacts of acidification on marine ecosystems."

Prince Albert II used the declaration to voice his concerns, adding that he hoped the world's leaders would take the "necessary action" at a key UN climate summit later this year.

"I strongly support this declaration. I hope that it will be heard by all the political leaders meeting in Copenhagen in December 2009."

 

* The oceans are thought to have absorbed about half of the extra CO2 put into the atmosphere in the industrial age

 

* This has lowered its pH by 0.1

 

* pH is the measure of acidity and alkalinity

 

* The vast majority of liquids lie between pH 0 (very acidic) and pH 14 (very alkaline); 7 is neutral

 

* Seawater is mildly alkaline with a "natural" pH of about 8.2

 

* The IPCC forecasts that ocean pH will fall by "between 0.14 and 0.35 units over the 21st Century, adding to the present decrease of 0.1 units since pre-industrial times"

 

 

Story from BBC NEWS:http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/7860350.stm---

 

Marine life faces 'acid threat'

 

 

 

By Julian Siddle Science Reporter, BBC News

Man-made pollution is raising ocean acidity at least 10 times faster than previously thought, a study says.

Researchers say carbon dioxide levels are having a marked effect on the health of shellfish such as mussels.

They sampled coastal waters off the north-west Pacific coast of the US every half-hour for eight years.

The results, published in the journal PNAS, suggest that earlier climate change models may have underestimated the rate of ocean acidification.

 

Ocean pH

Professor Timothy Wootton from the department of ecology and evolution, University of Chicago, in Illinois, says such dramatic results were unexpected as it was thought that the huge ocean systems had the ability to absorb large quantities of CO2.

"It's been thought pH in the open oceans is well buffered, so it's surprising to see these fluctuations," he said.

The findings showed that CO2 had lowered the water pH over time, demonstrating a year-on-year increase in acidity.

 

The research involved taking daily measurements of water pH levels, salinity and temperature, off the coast of Tatoosh island, a small outcrop lying in the Pacific Ocean, just off the north-western tip of Washington state, US.

As well as measuring physical factors, the health of marine life present in the coastal ecosystem was also tracked.

Professor Wootton says biological factors were missing from previous models of ocean climate systems - and that life in the ocean, or in this case on the ocean edge, can also affect seawater pH.

"Over a short time, biology is affecting pH, through photosynthesis and respiration, but current models don't include biological activity as part of the story," he explained.

Calcium carbonate

Every summer, Professor Wootton returned to the same sites on Tatoosh island's windswept coasts, to look at the abundance and distribution of life at the water's edge. He was especially interested in barnacles, algae and the dominant species, the Californian mussel.

 

The mussel has a calcium carbonate -based shell, which can be weakened or even dissolved by exposure to acid. Professor Wootton says the increase in acidity may be responsible for the decline in mussels noted in the study.

"Patterns show the chances of mussels being replaced are higher than for species without calcified shells," he said.

Other species quickly move into the space previously occupied by the mussels - though one of these species, the barnacle, also has calcified shells.

To explain this apparent anomaly, Professor Wootton says the decline of the dominant species allows a window where another species may thrive - though he expects this to be temporary as the interloper too will eventually be affected by the increasing acidity.

"In the short term, the long term decline is offset by the release from competition," he explained.

 

Chemical oceanography

The researchers say they were surprised that the plants and animals in their study are so sensitive to CO2 changes. These organisms live in the harsh inter-tidal zones, they may be submerged under water, exposed to the sun, then lashed by waves and storms.

Professor Wootton says the most troubling finding is the speed of acidification, with the pH level dropping at a much greater rate than was previously thought.

"It's going down 10 to 20 times faster than the previous models predicted," he says.

The research team are now working together with chemical oceanographers to see how their coastal observations can be matched with large scale observations, to try to explain why the decline in pH levels seems to be happening so quickly.

"We actually know surprisingly little about how ocean acidity is changing over time, we need a broader network of measurements," said Professor Wootton.

 

Story from BBC NEWS:http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/7745714.stmPublished: 2008/11/25 00:51:28 GMT