'Underwater catastrophe' is imminent without action
Steve Connor, The Independent 1 Jun 09;
Rising acidity in oceans is leading to a global catastrophe that would be unparalleled in tens of millions of years, according to the national science academies of 69 countries which want governments to take the issue more seriously in the run-up to the December climate change conference in Copenhagen.
The rate at which the oceans are turning acidic because of rising carbon dioxide concentrations in the atmosphere is faster than at any other time since the extinction of the dinosaurs 65 million years ago, the scientists said in a joint statement issued today in advance of this week's pre-Copenhagen conference on climate change in Bonn.
As carbon dioxide increases in the air above the ocean, more of the gas gets dissolved in the surface water of the sea, creating carbonic acid. Since the start of the industrial revolution, the acidic activity of the oceans has increased by 30 per cent. At current rates, they will become so acidic that few shell-forming organisms and coral reefs will be able to survive by mid-century.
The academies, which include those in China and the US, have called on governments to treat ocean acidification as an important problem caused by the rising levels of man-made carbon dioxide, urging them to agree on significant cuts in carbon dioxide emissions – at least to half of 1990 levels by 2050. Lord Rees of Ludlow, the president of the Royal Society – Britain's national academy of sciences – said: "Unless global CO2 emissions can be cut by at least 50 per cent by 2050 and more thereafter, we could confront an underwater catastrophe, with irreversible changes in the makeup of our marine biodiversity," Lord Rees said.
It is estimated that the oceans have absorbed about a quarter of man-made carbon dioxide emissions since the industrial revolution but one of the outcomes of this absorption has been a fall in the natural alkalinity of the sea and a corresponding increase in its acidity.
As carbon dioxide dissolves in water, it produces acidic hydrogen ions which attack the carbonate ions that are the building blocks of the calcium shells and skeletons used by corals and shellfish. Carbonate ion concentrations are lower now than at any other time in the past 800,000 years, the panel said.
"Global atmospheric CO2 concentrations are now at 387 parts per million ... model projections suggest that by mid-century, CO2 concentrations will be more than double pre-industrial levels and the oceans will be more acidic than they have been for tens of millions of years," the panel said.
"These changes in ocean chemistry are irreversible for many thousands of years, and the biological consequences could last much longer."
Even if levels of carbon dioxide were stabilised at the target of 450 parts per million, more than 90 per cent of tropical coral reefs will be affected by uncomfortably high levels of acidity. Stabilisation at 550 parts per million could result in reefs dissolving.
Climate change turning seas acid: scientists
Reuters 1 Jun 09;
BONN, Germany (Reuters) - Climate change is turning the oceans more acid in a trend that could endanger everything from clams to coral and be irreversible for thousands of years, national science academies said on Monday.
Seventy academies from around the world urged governments meeting in Bonn for climate talks from June 1-12 to take more account of risks to the oceans in a new U.N. treaty for fighting global warming due to be agreed in Copenhagen in December.
"To avoid substantial damage to ocean ecosystems, deep and rapid reductions of carbon dioxide emissions of at least 50 percent (below 1990 levels) by 2050, and much more thereafter, are needed," the academies said in a joint statement.
The academies said rising amounts of carbon dioxide, the main greenhouse gas emitted mainly by human use of fossil fuels, were being absorbed by the oceans and making it harder for creatures to build protective body parts.
The shift disrupts ocean chemistry and attacks the "building blocks needed by many marine organisms, such as corals and shellfish, to produce their skeletons, shells and other hard structures," it said.
On some projections, levels of acidification in 80 percent of Arctic seas would be corrosive to clams that are vital to the food web by 2060, it said.
And "coral reefs may be dissolving globally," it said, if atmospheric levels of carbon dioxide were to rise to 550 parts per million (ppm) from a current 387 ppm. Corals are home to many species of fish.
"These changes in ocean chemistry are irreversible for many thousands of years, and the biological consequences could last much longer," it said.
The warning was issued by the Inter-Academy Panel, representing science academies of countries from Albania to Zimbabwe and including those of Australia, Britain, France, Japan and the United States.
UNDERWATER CATASTROPHE
Martin Rees, president of the Royal Society, the British science academy, said there may be an "underwater catastrophe."
"The effects will be seen worldwide, threatening food security, reducing coastal protection and damaging the local economies that may be least able to tolerate it," he said.
The academies' statement said that, if current rates of carbon emissions continue until 2050, computer models indicate that "the oceans will be more acidic than they have been for tens of millions of years."
It also urged actions to reduce other pressures on the oceans, such as pollution and over-fishing.
(Editing by Michael Roddy)
Scientists warn acid is killing oceans
Deborah Smith, Sydney Morning Herald 2 Jun 09;
RISING carbon dioxide emissions are turning the oceans acidic in an irreversible process that threatens coral reefs and food security, the world's scientific academies have warned.
Seventy academies, including the Australian Academy of Science, urged governments meeting in Bonn for climate talks to tackle the issue in the new United Nations treaty on climate change to be agreed in Copenhagen in December.
In the past 200 years the world's oceans have absorbed about a quarter of the carbon dioxide produced by human activities, and the current rate of acidification is much more rapid than at any time during the past 65 million years, the scientists said in a joint statement.
Martin Rees, president of the Royal Society in Britain, said that unless global carbon dioxide emissions were cut by at least 50 per cent of 1990 levels by 2050 there could be an "underwater catastrophe" and loss of marine life.
"The effects will be seen worldwide, threatening food security, reducing coastal protection and damaging local economies that may be least able to tolerate it," Professor Rees said. "Copenhagen must address this very real and serious threat."
As carbon dioxide dissolves it alters ocean chemistry, leading to an attack on the carbonate building blocks needed by marine organisms, such as corals and shellfish, to produce their skeletons, shells and other hard structures.
"Ocean acidification is irreversible on timescales of at least tens of thousands of years," the scientists said.
Although it was a global problem, some areas, including the tropical waters around the Great Barrier Reef, would be more affected than others.
Terry Hughes, director of the Australian Research Council Centre for Coral Reef Studies at James Cook University, said the effects have already been observed. "We have clear evidence that the growth rate of corals is slowing because of ocean acidification."
The Great Barrier Reef was under stress as well from higher water temperatures, said Professor Hughes, who contributed to the academies' statement.
"Unless the world can sharply reduce greenhouse gas emissions, the combination of repeated bouts of bleaching, more extreme storms and slower growth due to acidification will have a severe impact on coral reefs and the tourism and fisheries industries they support," he said. "We only have a narrow window of opportunity to prevent further severe damage to coral reefs before it's too late."
Will Howard, an oceanographer at the Antarctic Climate and Ecosystems Co-operative Research Centre in Hobart, said the issue of acidification was independent of debates about possible effects of global warming.
"The impact is happening now in nature, not in computer simulation or in laboratory manipulation, and can be directly attributed to carbon dioxide emissions," Dr Howard said.
If carbon dioxide levels, now at 387 ppm, were stabilised at 450 ppm, more than 10 per cent of the world's oceans would be affected by acidification, including more than 90 per cent of all tropical and subtropical coral reefs.
Stabilisation at 550 ppm could result in coral reefs "dissolving globally", the scientists said.
Adding chemicals to the oceans to try to counter acidification was likely to be expensive, only partly effective at local sites and could pose unknown risks.
