Roger Harrabin, BBC News 11 Mar 09;
Carbon dioxide emissions from human activities are acidifying the oceans and threaten a mass extinction of sea life, a top ocean scientist warns.
Dr Carol Turley from Plymouth Marine Laboratory says it is impossible to know how marine life will cope, but she fears many species will not survive.
Since the Industrial Revolution, CO2 emissions have already turned the sea about 30% more acidic, say researchers.
It is more acidic now than it has been for at least 500,000 years, they add.
The problem is set to worsen as emissions of the greenhouse gas increase through the 21st Century.
"I am very worried for ocean ecosystems which are currently productive and diverse," Carol Turely told BBC News.
"I believe we may be heading for a mass extinction, as the rate of change in the oceans hasn't been seen since the dinosaurs.
"It may have a major impact on food security. It really is imperative that we cut emissions of CO2."
Dr Turley is chairing a session on ocean acidification at the Copenhagen Climate Change Congress.
Testing times
The problem is most acute for creatures which make calcified shells.
Laboratory tests suggest starfish may be wiped out before the end of the century if current emissions trends continue.
Scientists fear mussels may not be able to cope, either. Oysters may be less vulnerable, and farmed oysters may fare better than wild oysters.
"One thing is certain," says Dr Turley. "Things will change. We just don't know yet exactly how they will change.
"It is not a very wise experiment to be making."
Professor Andy Watson, an ocean biologist from the University of East Anglia, believes climate change and overfishing may ruin the seas before acidification does.
He condemns increases in CO2 from human activities, but points out that ocean acidity also fluctuates naturally.
He also wonders if some creatures might adapt to the changes over time.
"(In) many of the experiments that are being done at the moment, sudden changes are made; the CO2 is quickly raised, for example, or the acidity is quickly raised.
"Of course, that's not really what will happen in the real world," he told BBC News.
"There will be instead a gradual ramping up of CO2 and acidity. And we don't know whether organisms will be able to adapt or how quickly they'll be able to adapt."
Professor Tony Knapp runs the BIOS institute in Bermuda, where some of the key measurements of acidity are taken.
He defends his conclusion that the recent increase in acidity has been caused by CO2 emissions from burning fossil fuels.
"It took me a long time to determine that I was convinced... I'm a cynic at heart.
"But if you look at the data, and you're intimate with the data, there's really no other conclusion you could make".
Stormy waters
On the island of Ischia, in the Bay of Naples, Italy, scientists believe they have evidence that many creatures will fail to adapt to increased acidification.
The seawater around a part of the island has been more acidic for thousands of years thanks to volcanic CO2 vents that turn the seabed into a sort of jacuzzi.
If research here presents an accurate picture of future oceans, the prospects for shell-forming organisms are bleak.
Some of the creatures that appear to survive increased levels of acidity in short-term laboratory studies are not present here in the real world at the same levels of pH.
"We are very worried," says Dr Jason Hall-Spencer from Plymouth University, who researches the site with help from the Naples-based Benthic Ecology Laboratory at Stazione Zoologica.
"The changes here have clearly made life impossible for shell-forming creatures.
"When you start messing around with a complex ecosystem it is impossible to tell what will happen."
The Ischia site does not present a perfect experiment for future oceans because levels of acidity shift regularly as the currents change, whereas future oceanic pH levels will be more stable.
But the site does show clear winners and losers: the lush seagrass, hyper-fertilised by CO2, may be the tallest in the world.
The extra acidity will suit some creatures, but Dr Hall-Spencer argues that the diversity of the site is reduced and therefore it is likely that productivity of valuable species will diminish in future acidified oceans.
Ocean acidification is increasingly known as "the other CO2 problem".
It is a new branch of science and researchers were initially uncertain how seriously to take the threat.
"In 2004, I did a Google search for ocean acidification and got 17 hits," says Dr Turley.
"Now you get hundreds of thousands. There is much more evidence to show this will be a problem for the future - indeed it may even be a problem for now."
For many people it will strike a sobering note that humans appear to be changing the chemistry of the mighty oceans.
OCEAN ACIDIFICATION
THE pH SCALE
Higher numbers indicate alkalis, lower values signify acidic liquids:
- 13 - bleach
- 10 - soap
- 8.2 - pre-1750 oceans (average)
- 8.1 - current oceans (average)
- 7.8 - oceans in 2100 (projected average)
- 7 - pure water
- 3 - vinegar
- 0 - battery acid
( Source: NMEA )
'Coral lab' offers acidity insight
Roger Harrabin, BBC News 12 Mar 09;
Five metres under the blue waters of the Red Sea in Eilat, Israel, we're examining a long steel table arrayed like a plant nursery with ranks of near-identical specimens.
They're not plants, they're corals, which are being cultivated for experiments into ocean acidification.
The specimens are taken to one of the world's most desirable science laboratories - the Interuniversity Institute for Marine Science, located right on the beach at Eilat.
There, scientists are reaching worrying conclusions, particularly for the hundreds of millions of people who rely on fish that depend on coral reefs.
The project is led by a lean triathlete, Dr Maoz Fine.
He started by measuring the growth rate of corals at a pH of 7.9, which is about the same level that the world's oceans, on average, are expected to reach by the end of the century.
To his surprise, the corals - which produce alkaline shells - were only slightly affected by the decrease in alkalinity during the one-year experiment.
He lowered the water's pH to 7.6, which is roughly equivalent to about 1,500 parts per million of CO2 in the atmosphere.
The unpublished experiment is controversial because it creates conditions much worse than even the most pessimistic forecast.
Dr Fine defends it because he says we need to find as soon as possible whether different corals will react differently to higher acidity by pushing the limits of coral physiology to extreme.
He was amazed to find that the fast-growing branching corals (Stylophora pistillata) did well even under this low pH.
But the slow-growing corals (Porites), which form the bedrock of the reefs, were demonstrably harmed.
Far more alarming is the experiment on a humble calcareous algae, which looks like pink paint on a rock.
This algae plays a vital role in cementing reefs together. But it cannot survive the pH levels of 8.0 predicted before the end of the century, possibly as early as 2050.
That means the reefs are likely to begin to crumble.
"Corals will continue to exist," Dr Fine says, "but the reefs will be greatly changed from what we know now and their biodiversity will be dramatically reduced.
"This will make them much more vulnerable to other catastrophic events, like bleaching.
"We are piling problems upon each other."
Dr Fine fears another mass coral extinction is possible, like ones that have happened during acidic episodes in the past.
The fossil record shows that each time corals have bounced back, albeit with a different combination of species and over millions of years.
Dr Fine's laboratory has discovered that the creature that forms the reefs - the coral polyp - flees its shell if conditions become inhospitable.
This makes it more vulnerable to predators, but it is able to survive and reproduce while swimming in open water.
Scientists leading the work on ocean acidification hope it will be another spur to persuade politicians to cut CO2 emissions, which are changing the ocean by warming the planet.
The inexorable linear progress of acidification is much more predictable than climate change, they say.
But one leading coral scientist, Tom Goreau of the Global Coral Reef Alliance, describes acidification as a "fad", distracting the world from climate change.
"The increase in direct surface temperature is a far more serious and immediate threat to reefs than acidification," he says in an article for the Alliance.
"Acidification will only dissolve the dead skeletons after high temperatures kill the corals.
"So focusing on acidification amounts to a red herring and effectively ignores a far larger and more immediate problem."
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