The SMH has a look at the toll carbon emissions are taking on the oceans - Intensifying ocean acidity from carbon emissions hitting Pacific shellfish industry.

For more than a century, Bill Taylor's family has used the calm, protected waters of Puget Sound to raise oysters, planting billions of larvae in underwater beds and then harvesting them to ship to some of the finest restaurants in the world.

But then something went wrong. After the hatchery produced peak levels of seven billion larvae in 2006 and 2007, the numbers began to drop precipitously. In 2008, it had just half as many larvae. By 2009, it produced less than a third of the peak.

Up and down the Pacific Coast, from California to British Columbia to Alaska, other shellfish farms experienced the same decline: Something was happening to their larvae at the formative stage of life when they build their shells. No one in the industry knew why "We didn't know that much about the water because we didn't have any problems," Taylor said. Once the larvae started dying off, they tested the water: It was much too acidic.

Scientists testing the water up and down the Pacific Coast found evidence of the same steep decline in pH. Studies have found more acidic water in Alaska is stunting the growth of red king crabs and tanner crabs. Plummeting pH levels across the Eastern Seaboard have been impacting the shellfish industry for decades.

The economic impacts of rising acidity can be devastating. At its peak in 1952, U.S. producers harvested 72 million pounds of eastern oysters, according to data collected by the National Marine Fisheries Service. In 2012, the last year for which data is available, farmers hauled in just 23.8 million pounds. Producers haven't harvested more than 30 million pounds since 1996.

In a new study published online in the scholarly journal Progress in Oceanography, a team of scientists from the National Oceanic and Atmospheric Administration found rural areas in southern Alaska are at high risk of losing hundreds of millions of dollars in commercial and subsistence fishing stocks. Declining seafood harvests will impact about 20 per cent of Alaska's population, which relies on subsistence fishing for significant amounts of their diet, the NOAA report found.

The acidification of the world's oceans frightens scientists, who see it as evidence of a rapidly changing climate. Though not as evident as increasingly powerful storms or devastating droughts, ocean acidification may be the clearest example of man's impact on the changing climate.

Acidification happens as a result of increased carbon in the atmosphere. The top layer of the world's oceans, perhaps the first 100 metres, absorb the elements in the atmosphere. The more carbon, the more acidic the water becomes. Currents take that layer of surface water and plunge it into the depths of the Pacific; decades later, the water is forced back to the surface as it reaches the West Coast, a process scientists call upwelling.

The Observer has a report on ocean acidification in the Arctic, noting "with the world's oceans absorbing six million tonnes of carbon a day, a leading oceanographer warns of eco disaster" - Arctic seas turn to acid, putting vital food chain at risk.

Carbon-dioxide emissions are turning the waters of the Arctic Ocean into acid at an unprecedented rate, scientists have discovered. Research carried out in the archipelago of Svalbard has shown in many regions around the north pole seawater is likely to reach corrosive levels within 10 years. The water will then start to dissolve the shells of mussels and other shellfish and cause major disruption to the food chain. By the end of the century, the entire Arctic Ocean will be corrosively acidic.

"This is extremely worrying," Professor Jean-Pierre Gattuso, of France's Centre National de la Recherche Scientifique, told an international oceanography conference last week. "We knew that the seas were getting more acidic and this would disrupt the ability of shellfish – like mussels – to grow their shells. But now we realise the situation is much worse. The water will become so acidic it will actually dissolve the shells of living shellfish."

Grist has a post on warnings about ocean acidifcation caused by carbon emissions - Dropping Acid.

If the idea of acidic oceans sounds problematic, it should. The carbon emissions that trap heat in the atmosphere also wind up in the ocean, where they dissolve and turn the water acidic. This lowering of the pH of seawater -- already underway -- threatens coral reefs, shellfish, and the vast food chains to which they belong.

Today 155 scientists issued a report on the rising danger of ocean acidification, saying swift and drastic emissions cuts are needed to curb the problem. The Monaco Declaration [PDF] is based on the work of the Second International Symposium on the Ocean in a High-CO2 World, held in Monaco last October. It's not the first warning scientists have issued about ocean acidification, though the call to action from scientists from 26 countries is unusually strongly worded:

Ocean acidification could affect marine food webs and lead to substantial changes in commercial fish stocks, threatening protein supply and food security for millions of people as well as the multi-billion dollar fishing industry by mid-century, ocean acidification may render most regions chemically inhospitable to coral reefs. These and other acidification-related changes could affect a wealth of marine goods and services, such as our ability to use the ocean to manage waste, to provide chemicals to make new medicines, and to benefit from its natural capacity to regulate climate.

The report aims to reposition ocean acidification from a peripheral environmental issue to "the other CO2 problem that must be grappled with alongside climate change." Additionally, as the pH of seawater falls, the process reduces the ocean's ability to absorb more carbon. Oceans currently absorb one quarter of the CO2 emitted by human activities, the report says.

The solution to acidification is essentially the same as that for climate change -- reduce carbon emissions. The declaration's action points are quite predictable: More research, bring policymakers and economists on board, and enact a global carbon emissions plan. Acidification doesn't require a separate plan as much as it provides another reason for an aggressive global climate treaty.

The Economist has a special report on the sea, with the lead article looking at the impact of human activity on the oceans - Troubled waters. There is a companion piece called A sea of troubles which points out "Man is assaulting the oceans. They will smite him if he does not take care".

HUMAN beings no longer thrive under the water from which their ancestors emerged, but their relationship with the sea remains close. Over half the world’s people live within 100 kilometres (62 miles) of the coast; a tenth are within 10km. On land at least, the sea delights the senses and excites the imagination. The sight and smell of the sea inspire courage and adventure, fear and romance. Though the waves may be rippling or mountainous, the waters angry or calm, the ocean itself is eternal. Its moods pass. Its tides keep to a rhythm. It is unchanging.

Or so it has long seemed. Appearances deceive, though. Large parts of the sea may indeed remain unchanged, but in others, especially in the surface and coastal waters where 90% of marine life is to be found, the impact of man’s activities is increasingly plain. This should hardly be a surprise. Man has changed the landscape and the atmosphere. It would be odd if the seas, which he has for centuries used for food, for transport, for dumping rubbish and, more recently, for recreation, had not also been affected.

The evidence abounds. The fish that once seemed an inexhaustible source of food are now almost everywhere in decline: 90% of large predatory fish (the big ones such as tuna, swordfish and sharks) have gone, according to some scientists. In estuaries and coastal waters, 85% of the large whales have disappeared, and nearly 60% of the small ones. Many of the smaller fish are also in decline. Indeed, most familiar sea creatures, from albatrosses to walruses, from seals to oysters, have suffered huge losses.

All this has happened fairly recently. Cod have been caught off Nova Scotia for centuries, but their systematic slaughter began only after 1852; in terms of their biomass (the aggregate mass of the species), they are now 96% depleted. The killing of turtles in the Caribbean (99% down) started in the 1700s. The hunting of sharks in the Gulf of Mexico (45-99%, depending on the variety) got going only in the 1950s.

The habitats of many of these creatures have also been affected by man’s activities. Cod live in the bottom layer of the ocean. Trawlermen in pursuit of these and other groundfish like pollock and haddock drag steel weights and rollers as well as nets behind their boats, devastating huge areas of the sea floor as they go. In the Gulf of Mexico, trawlers ply back and forth year in year out, hauling vast nets that scarify the seabed and allow no time for plant and animal life to recover. Off New England, off west Africa, in the Sea of Okhotsk north of Japan, off Sri Lanka, wherever fish can still be found, it is much the same story.

Coral reefs, whose profusion of life and diversity of ecosystems make them the rainforests of the sea, have suffered most of all. Once home to prolific concentrations of big fish, they have attracted human hunters prepared to use any means, even dynamite, to kill their prey. Perhaps only 5% of coral reefs can now be considered pristine, a quarter have been lost and all are vulnerable to global warming.

A hotter atmosphere has several effects on the sea. First, it means higher average temperatures for surface waters. One consequence for coral reefs is that the symbiosis between the corals and algae that constitute a living reef is breaking down. As temperatures rise, the algae leave or are expelled, the corals take on a bleached, white appearance and may then die.

Warming also has consequences for ice: it melts. Melting sea ice affects ecosystems and currents. It does not affect sea levels, because floating ice is already displacing water of a weight equal to its own. But melting glaciers and ice sheets on land are bringing quantities of fresh water into the sea, whose level has been rising at an average of nearly 2 millimetres a year for over 40 years, and the pace is getting faster. Recent studies suggest that the sea level may well rise by a total of 80 centimetres this century, though the figure could plausibly be as much as 2 metres.

The burning over the past 100 years or so of fossil fuels that took half a billion years to form has suddenly, in geological terms, put an enormous amount of carbon dioxide into the atmosphere. About a third of this CO2 is taken up by the sea, where it forms carbonic acid. The plants and animals that have evolved over time to thrive in slightly alkaline surface waters—their pH is around 8.3—are now having to adapt to a 30% increase in the acidity of their surroundings. Some will no doubt flourish, but if the trend continues, as it will for at least some decades, clams, mussels, conches and all creatures that grow shells made of calcium carbonate will struggle. So will corals, especially those whose skeletons are composed of aragonite, a particularly unstable form of calcium carbonate.

Man’s interference does not stop with CO2. Knowingly and deliberately, he throws plenty of rubbish into the sea, everything from sewage to rubber tyres and from plastic packaging to toxic waste. Inadvertently, he also lets flame retardants, bunker oil and heavy metals seep into the mighty ocean, and often invasive species too. Much of the harm done by such pollutants is invisible to the eye: it shows up only in the analysis of dead polar bears or in tuna served in New York sushi bars.

Increasingly, though, swimmers, sailors and even those who monitor the sea with the help of satellites are encountering highly visible algal blooms known as red tides. These have always occurred naturally, but they have increased in frequency, number and size in recent years, notably since man-made nitrogen fertilisers came into widespread use in the 1950s. When rainwater contaminated with these fertilisers and other nutrients reaches the sea, as it does where the Mississippi runs into the Gulf of Mexico, an explosion of toxic algae and bacteria takes place, killing fish, absorbing almost all the oxygen and leaving a microbially dominated ecosystem, often based on a carpet of slime.

Each of these phenomena would be bad enough on its own, but all appear to be linked, usually synergistically. Slaughter one species in the food web and you set off a chain of alterations above or below. Thus the near extinction of sea otters in the northern Pacific led to a proliferation of sea urchins, which then laid waste an entire kelp forest that had hitherto sustained its own ecosystem. If acidification kills tiny sea snails known as pteropods, as it is likely to, the Pacific salmon that feed upon these planktonic creatures may also die. Then other fish may move in, preventing the salmon from coming back, just as other species did when cod were all but fished out in Georges Bank, off New England.

Climate skeptics usually ignore one of the other major problems with carbon dioxide emissions - the oceans are growing more acidic as they absorb more CO2 - Ocean growing more acidic faster than once thought.

University of Chicago scientists have documented that the ocean is growing more acidic faster than previously thought. In addition, they have found that the increasing acidity correlates with increasing levels of atmospheric carbon dioxide, according to a paper published online by the Proceedings of the National Academy of Sciences on Nov. 24.

"Of the variables the study examined that are linked to changes in ocean acidity, only atmospheric carbon dioxide exhibited a corresponding steady change," said J. Timothy Wootton, the lead author of the study and Professor of Ecology and Evolution at the University of Chicago.

The increasingly acidic water harms certain sea animals and could reduce the ocean's ability to absorb carbon dioxide, the authors said. Scientists have long predicted that higher levels of atmospheric carbon dioxide would make the ocean more acidic. Nevertheless, empirical evidence of growing acidity has been limited.

The new study is based on 24,519 measurements of ocean pH spanning eight years, which represents the first detailed dataset on variations of coastal pH at a temperate latitude—where the world's most productive fisheries live.

"The acidity increased more than 10 times faster than had been predicted by climate change models and other studies," Wootton said. "This increase will have a severe impact on marine food webs and suggests that ocean acidification may be a more urgent issue than previously thought, at least in some areas of the ocean."

The ocean plays a significant role in global carbon cycles. When atmospheric carbon dioxide dissolves in water it forms carbonic acid, increasing the acidity of the ocean. During the day, carbon dioxide levels in the ocean fall because photosynthesis takes it out of the water, but at night, levels increase again. The study documented this daily pattern, as well as a steady increase in acidity over time.

"Many sea creatures have shells or skeletons made of calcium carbonate, which the acid can dissolve," said Catherine Pfister, Associate Professor of Ecology and Evolution at the University of Chicago and a co-author of the study. "Therefore, the increased acidity of the ocean could interfere with many critical ocean processes such as coral reef building or shellfish harvesting."

The Australian has an article on the looming danger of ocean acidifcation. This is a good one to run past any global warming skeptics out there that are happy to pretend that carbon emissions don't cause global warming - how about acid oceans ?

NOW that Ross Garnaut's draft report has been released, most of the climate change debate in Australia will focus on the economic effects of any emissions trading scheme.

However, there's another carbon problem, which will profoundly affect our oceans, that has received scant attention beyond a small band of marine scientists and is largely independent of global warming.

The public, aware of the role of carbon dioxide in climate change, doesn't know of its function in acidifying the oceans and the hundreds of years that would be required for recovery.

Ocean acidification refers to the natural process whereby carbon dioxide dissolves in the sea, forming a weak carbonic acid. The ocean is a major sink for atmospheric carbon dioxide and has absorbed about 48 per cent of the CO2 emitted by human activities since the pre-industrial age.

A recent report from the Antarctic Climate and Ecosystems Co-operative Research Centre claimed that carbon dioxide in the atmosphere is at its highest level in 650,000 years, and possibly 23 million years, and half has been dissolved in the oceans, making them more acidic.

Australia has a direct stake in the ocean acidification problem: it will affect every part of our marine environment. And our offshore estate has just become a lot bigger. Three months ago the UN Commission on the Limits of the Continental Shelf, while not accepting all bids, recognised Australia's claim to the continental shelf where it extends beyond our exclusive 200 nautical mile economic zone. This is a vast oceanic area: 2.5 million square kilometres, or 10 times the size of New Zealand and 20 times the size of Britain.

Rising levels of acidity in the oceans surrounding Australia could have a profound impact on marine industries and dire consequences for many Pacific Island communities, presenting strategic and humanitarian challenges.

Mounting levels of CO2 in the Southern Ocean has caused deep concern among scientists studying the long-term productivity of the world's oceans. Under conditions of increasing acidification, parts of the oceans will deteriorate and progressively become uninhabitable for certain types of plankton, central to the ocean food chain, and coral structures. The Southern Ocean is particularly important because it is very efficient at absorbing CO2 from the atmosphere: it's here where the first effects are being felt.

Ocean acidification is likely to have a cascading effect, reaching parts of the food chain such as fish and shellfish. Marine researchers are saying that a business-as-usual scenario of CO2 production will ultimately result in destruction of marine life on an enormous scale.