ACIDIC OCEANS AFFECTING FOOD FISH
By Dan Shapley
Carbon dioxide emissions could shake "the biological underpinnings of civilization" as increasingly acidic water undermines the oceanic food web, according to fresh research from the Pacific Ocean off Alaska.
The research shows that increasingly acidic Pacific water will affect king crabs and a snail that is a favorite food of Pacific salmon. How disruptions in the ocean food web could ultimately harm these and other popular food species is still uncertain.
The Senate Subcommittee on Oceans, Atmosphere, Fisheries, and Coast Guard will hear testimony today on the acidification of oceans from private, government and environmental group scientists.
Oceans had until recently been viewed as a great savior of the climate, because they have absorbed about one third of the carbon humans have emitted, buffering what would otherwise have been a greater warming of the atmosphere. But scientists have in recent years begun studying the consequences of oceanic carbon storage -- a 25 percent increase in acidity since pre-industrial times.
The scientific endeavor is still young, with many unanswered questions. But results have shifted from showing that the ocean has grown more acidic to showing how that acidification is affecting ocean life, including species important for human food.
"We're starting to see now a real connection to fisheries," said Christopher Sabine, a National Oceanographic and Atmospheric Administration scientist involved in the North American Carbon Program's effort to understand the role of carbon in the oceans.
Victoria Fabry, a biological oceanographer at the University of California, has found that the shells of pteropods -- a set of 32 planktonic snails sometimes called sea butterflies -- dissolve in acidic water, and that the layer of water acidic enough to do so is slowly expanding from the depths toward the surface as the ocean absorbs more carbon. If carbon dioxide emissions continue unabated, surface water could be corrosive to shells by between 2050 and 2100, depending on different emissions scenarios.
Pteropods are widely consumed by a variety of ocean life, including several species of salmon. More than 60 percent of a salmon's diet can be pteropod, according to the research of Katherine Myers, the principle investigator for the University of Washington's High Seas Salmon Research Program. How acidification affects pteropods, and in turn salmon, will be the subject of future research.
"We know the chemistry of it very well, and with a great deal of certainty, but what the ecological impacts will be on fisheries, on overall productivity, regional productivity, we simply do not know," Fabry said. "This is a case where we do need additional research."
The importance of pteropods to a popular food fish like salmon gives the acidification research a sense of urgency: The effects of acidification could creep up the food chain.
"And we're at the top," said Thomas Lovejoy, the executive director of the H. John Heinz III Center for Science, Economics and the Environment. He made his remarks at a Wildlife Trust lunch, and in an interview with The Daily Green.
Lovejoy called the acidification of the oceans "the most profound environmental change I've encountered in my professional career," and said the consequences for ocean life are "shaking the biological underpinnings of civilization."
New research also shows that acidification is having effects on king crabs, though the lead scientist on that project, Jeff Short of the National Oceanographic and Atmospheric Administration, said he was withholding details until his research has been peer-reviewed and published.
The vanguard research has been conducted as scientists try to quickly come up to speed on the role of carbon in the oceans. Conferences in recent weeks have allowed scientists to share results and frame goals for future research.
A grade school science experiment can demonstrate how carbon dioxide makes water acidic. Blow into a glass of water with a straw, creating bubbles of breath -- largely made up of carbon dioxide -- and the pH of the water will drop. Still, the wholesale acidification of the oceans, "really sort of snuck up on everyone in the scientific community," Lovejoy said.
The stakes are potentially huge. Tens of thousands of species -- representing the first critical link or two on the food chain -- use calcium carbonate to construct shells. Different species produce different forms of calcium carbonate, with pteropods and corals among those that produce a form that is highly susceptible to corrosive conditions.
"We're not at the panic stage, obviously, but it certainly is a concern, and there's a direct link to CO2 emissions, which is very important, because it's something that humans have control over, and we can change that if we want to," Myers said. "Whereas global warming has both natural and anthropogenic [human] causes, it looks like there's a fairly direct link between acidification and carbon emissions by humans."
Copyright 2007 Hearst Communications, Inc.
CLIMATE CHANGE: A GUIDE FOR THE PERPLEXED
By Michael Le Page
Our planet's climate is anything but simple. All kinds of factors influence it, from massive events on the Sun to the growth of microscopic creatures in the oceans, and there are subtle interactions between many of these factors.
Yet despite all the complexities, a firm and ever-growing body of evidence points to a clear picture: the world is warming, this warming is due to human activity increasing levels of greenhouse gases in the atmosphere, and if emissions continue unabated the warming will too, with increasingly serious consequences.
Yes, there are still big uncertainties in some predictions, but these swing both ways. For example, the response of clouds could slow the warming or speed it up.
With so much at stake, it is right that climate science is subjected to the most intense scrutiny. What does not help is for the real issues to be muddied by discredited arguments or wild theories.
So for those who are not sure what to believe, here is our round-up of the 26 most common climate myths and misconceptions.
There is also a guide to assessing the evidence. In the articles we've included lots of links to primary research and major reports for those who want to follow through to the original sources.
** Human CO2 emissions are too tiny to matter
** We can't do anything about climate change
** The 'hockey stick' graph has been proven wrong
** Chaotic systems are not predictable
** We can't trust computer models of climate
** They predicted global cooling in the 1970s
** It's been far warmer in the past, what's the big deal?
** It's too cold where I live -- warming will be great
** Global warming is down to the Sun, not humans
** It's all down to cosmic rays
** CO2 isn't the most important greenhouse gas
** The lower atmosphere is cooling, not warming
** Antarctica is getting cooler, not warmer, disproving global warming
** The oceans are cooling
** The cooling after 1940 shows CO2 does not cause warming
** It was warmer during the Medieval period, with vineyards in England
** We are simply recovering from the Little Ice Age
** Warming will cause an ice age in Europe
** Ice cores show CO2 increases lag behind temperature rises, disproving the link to global warming
** Ice cores show CO2 rising as temperatures fell
** Mars and Pluto are warming too
** Many leading scientists question climate change
** It's all a conspiracy
** Hurricane Katrina was caused by global warming
** Higher CO2 levels will boost plant growth and food production
** Polar bear numbers are increasing
Copyright Reed Business Information Ltd.
From: Science (pg. 678)
A WORLD WITHOUT CORALS?
By Richard Stone
KHURA BURI, THAILAND -- In the shallow waters off Lan Island in the Andaman Sea, Kim Obermeyer kicks his flippers and glides over a silent graveyard. Scattered below are shards of staghorn and other branching corals, shattered in fragments that look like detached finger bones. The conservation biologist swims farther out to sea, darts to the bottom, and peers under an overturned Porites coral head the size of a Volkswagen Beetle. Obermeyer points to a brown ribbon underneath: a ragged colony soaking up just enough sun to have survived the tsunami that struck on 26 December 2004.
As a horrific tragedy unfolded on shore that day, ecosystems below the ocean's surface were getting hammered. Across Southeast Asia, the titanic waves ripped apart shallow reefs and buried others in silt. But tsunamis are not the worst threat. The main menaces are largely human-wrought: from divers clumsily breaking off chunks of coral to mass die-offs and bleaching of coral triggered by spikes in ocean temperatures. Last month, the Intergovernmental Panel on Climate Change (IPCC) forecast "more frequent coral bleaching events and widespread mortality" with average global temperature increases of 1 deg. to 3 deg. C.
Surveys suggest that 20% of the reefs on Earth, the largest living structures on the planet, have been destroyed in the past few decades. Another 50% are ailing or verging on collapse. "Reefs are likely to witness a significant ecological crisis in the coming half-century -- because of us," says coral specialist Camilo Mora of Dalhousie University in Halifax, Canada.
The decline of coral reefs may have staggering consequences. Globally, reefs generate about $30 billion per year in fishing, tourism, and protection to coasts from storm surges, says Mora. Although reefs cover a minuscule fraction (0.1%) of seabed, they are second only to rainforests in biodiversity, sheltering or nourishing up to 9 million species -- a third of all known marine life forms -- including 4000 kinds of fish. "To predict that reefs will change dramatically across the globe in the matter of a single generation should keep people up at night," says Ove Hoegh-Guldberg, director of the Centre for Marine Studies at the University of Queensland in St. Lucia, Australia.
There are a few rays of light in this bleak seascape. Attempts to rehabilitate tsunami-damaged reefs are showing promising results. Some reefs blighted by bleaching have mounted spectacular comebacks. And efforts to limit fishing and human activity have paid dividends in healthier reefs and revived local fisheries. Over the past decade, hundreds of marine protected areas have been established to safeguard reefs, including innovative MPAs in Palau designed to help corals bounce back after bleaching (see sidebar, p. 680).
Yet these gains could be erased by what's shaping up as the gravest threat of all. As the oceans soak up more and more of the carbon dioxide that humans pump into the atmosphere, marine chemistry is changing. CO2 emissions "have the potential to create chemical conditions in the ocean that have not occurred since the dinosaurs became extinct," says ecologist Kenneth Caldeira of the Carnegie Institution of Washington in Palo Alto, California. Dissolved in water, CO2 becomes carbonic acid. Caldeira coined a term for this process in a paper in 2003: "ocean acidification." By midcentury, ocean pH could dip so low that corals would be unable to form their calcium carbonate skeletons.
"Acidification is the big elephant in the room," says Terence Hughes, director of the Australian Research Council's Centre of Excellence for Coral Reef Studies at James Cook University in Townsville, Australia. Reef building would grind to a halt, with grievous implications. If CO2 emissions are not curtailed, Hughes predicts, "we'll eventually see reefs dominated by sea anemones and algae." Put another way, "soon we'll be having jellyfish and chips," says biologist Michael Kendall of the Plymouth Marine Laboratory in the United Kingdom. In the darkest scenarios, most corals will be toast.
A multiheaded monster
As coral reefs slip toward chronic frailty, a picture of what this means to the world has begun to emerge. Coral scientists, backed by an army of snorkeling and diving volunteers, have put a watch on critical reefs among the nearly 300,000 square kilometers charted to date. Hidden gems continue to come to light, including a giant deep-water reef in turbid waters off northern Australia. "Not much is known about the reef because nobody wants to swim in that area. It's infested with crocodiles," says oceanographer Alan Strong, senior consultant to the U.S. National Oceanic and Atmospheric Administration's (NOAA's) Coral Reef Watch.
A recurring theme of this heightened scrutiny is that reefs are vulnerable on many fronts. A March 2005 earthquake off Indonesia, for example, was as brutal as the 2004 tsunami, lifting some reefs clear out of the water (Science, 20 October 2006, p. 406). Corals are susceptible to pathogens and predators, too. The crown-of-thorns starfish, a periodic invader, denudes coral outcroppings with the efficiency of a slash-and-burn farmer. Meanwhile, corals are perpetually besieged by filamentous algae, which are held in check by fish that nibble at them. Overfishing can tilt the balance, as can sewage or agricultural runoff, which infuse seawater with algae- feeding nutrients. These abuses, along with coastal development, "are having fantastically large and negative impacts on reefs around the world," says John Pandolfi, a coral reef expert at the University of Queensland in Brisbane, Australia.
The latest and perhaps biggest present danger for reefs is bleaching. When sea surface temperatures exceed their normal summer high by 1 deg. C or more for a few weeks running, coral polyps, for reasons not entirely understood, expel their zooxanthellae, the symbiotic algae that lend corals color and provide nutrients. The polyps turn pale and starve. "If they don't get their zooxanthellae back in a month or so, they die," says Obermeyer.
The dangers of bleaching came to the fore in 1998, when a potent one- two climate punch -- a strong El Nino warming in central tropical Pacific waters, followed by a La Nina that heated western Pacific regions -- killed 16% of living corals worldwide (Science, 27 October 2000, p. 682). Some reefs have rallied from severe bleaching -- recently and dramatically, off Darwin Island in the Galapagos. "We'd given up on the Galapagos" after a 1982-83 bleaching event annihilated most of the archipelago's reefs, says Strong. Now, he says, "it seems to be really coming back." However, many bleached reefs are still sickly. At least half of those destroyed in 1998 have not recovered, according to the authoritative Status of Coral Reefs of the World: 2004, compiled by the Global Coral Reef Monitoring Network (GCRMN).
The catastrophic 1998 bleaching, and regional occurrences since then, highlight the vulnerability of reefs to global warming. "That's when we realized that corals could be a kind of canary in a coal mine," says Jeremy Goldberg, co-author of a GCRMN report on tsunami-inflicted reef damage. Delicate staghorn and elkhorn corals, for example, were listed as threatened in the Caribbean in May 2006 under the U.S. Endangered Species Act. "Branching corals that are sensitive to bleaching might disappear," warns reef ecologist Thamasak Yeemin of Ramkhamhaeng University in Bangkok.
Some reefs are more tolerant to bleaching. However, says Hoegh- Guldberg, "the movement toward hardier communities of fewer coral species is hardly a 'win.' " Coral abundance is still plummeting, and even resistant corals may succumb in a warmer world, he says. "As climate change accelerates, we will lose an increasing number of coral species, making ecosystems less resilient to other pressures."
A case in point is the widespread bleaching in the Caribbean Sea in 2005-06. At one reef off St. John, part of the U.S. Virgin Islands, "before people knew it, a disease infected the coral that had survived the bleaching. What was left was totally wiped out," Strong says. "You can see how this gets to be a multiheaded monster." NOAA and U.S. National Park Service scientists are now searching for clues to why some corals survived whereas others perished.
In an attempt to boost reef survival, governments have been setting up MPAs, which range from free-for-all recreational parks to no-take zones that bar fishing. Fewer than 3% of the world's reefs lie inside no-take MPAs, says Mora. Many reefs are being fished out. Raising the specter of a pending food crisis, a recent study found that 27 of 49 island countries are exploiting their reef fisheries in an unsustainable way, reports a team led by Nicholas Dulvy of the Centre for Environment, Fisheries, and Aquaculture Science in Lowestoft, U.K., in the 3 April issue of Current Biology.
Lax enforcement and lack of local buy-in have undercut many MPAs. "If communities are not involved, they are very unlikely to support an MPA imposed on them," says Obermeyer, coordinator for Reef Check Thailand. With volunteers from Reef Check and a second nonprofit, Earthwatch, Obermeyer endeavors to involve villagers -- and here near Khura Buri, the Ranong Coastal Resources Research Center of Kasetsart University -- in reef monitoring. "This is the only way to succeed," he says.
MPAs and measures such as stanching sewage and runoff cannot prevent bleaching. But resilience -- the capacity of a reef to absorb recurrent bleaching and still function -- can be enhanced, Hughes says. In 2002, more than half of Australia's 40,000-square-kilometer Great Barrier Reef bleached. Two years later, Australia created the world's largest no-take zones, extending fishing bans covering 4.6% of the reef to more than 33%. "This initiative provides real insurance cover against the inevitable impacts of climate change," says Hoegh- Guldberg.
To test this approach, Hughes and colleagues caged some reef sections and left others open to grazing by parrot-fish, known by their fused, beaklike teeth. Polyps reestablished on open reef three times faster than on caged sections, they report in the 20 February issue of Current Biology. The study shows that reef management after bleaching "has a big effect on the recovery rate," Hoegh-Guldberg says. But the strategy works only in the short run; nations must move rapidly to stem greenhouse gas emissions, he says. "It is next to useless not to do the two things together."
A mortal blow?
Until bleaching reared its head, many experts viewed rising sea levels as the chief peril of global warming for coral -- and a relatively toothless one at that. "We thought reefs would respond by just growing higher," says Strong. "Nobody was talking about changing sea chemistry." Then researchers came to the creeping realization that rising ocean acidity is likely to throw a spanner in coral physiology.
The threat is glaringly simple. Currently, ocean pH hovers around 8.1. Carbon dioxide absorbed into the water column lowers the pH, and as it falls, fewer carbonate ions are available for shell-building critters to grab. Even in present conditions, corals are fighting an uphill battle: Erosion removes 80% of the calcium carbonate laid down. Acidification will accelerate that process as rising carbonic acid levels deplete carbonate. Eventually, corals, plankton, and other organisms will fail to form skeletons. And coral skeletons are to reefs what girders are to skyscrapers. "You have a potential world in which reefs and the limestone frameworks they have built are in net erosion," says Hoegh-Guldberg.
IPCC scenarios of global emissions and ocean circulation indicate that by midcentury, atmospheric CO2 levels could reach more than 500 parts per million, and near the end of the century they could be above 800 ppm. The latter figure would decrease surface water pH by roughly 0.4 units, slashing carbonate ion concentration by half, paleocoral expert C. Mark Eakin, coordinator of NOAA's Coral Reef Watch, testified last month at a hearing in the U.S. House of Representatives. Ocean pH would be "lower than it has been for more than 20 million years," he said. And that does not factor in possible acidification from carbon- sequestration schemes now being considered.
Some coral species facing their acid test may become shape shifters to avoid extinction. New findings indicate that corals can survive acidic conditions in a sea anemone-like form and resume skeleton-building when returned to normal marine conditions (Science, 30 March, p. 1811). However, by pH 7.9, says Caldeira, "there would be a good chance reefs would be gone."
The potential for an acid-induced coral cataclysm has cast a pall on the tight-knit community of reef specialists. "The reality of coral reefs is very dark, and it is very easy for people to judge coral reef scientists as pessimists," says Mora. "We're becoming alarmist," adds Strong -- for good reason, he insists. "How are reefs going to handle acidification? It's not like sewage or runoff, where you may be able to just turn off the spigot." Queensland's Pandolfi, however, argues that it's "too early to make really definitive doom-and-gloom statements."
No one disputes that urgent action on greenhouse gas emissions is essential. "We could still have vibrant reefs in 50 years time," Hughes says. But these will not be the reefs we know today. "They will be dominated by a different suite of species," says Hughes, who notes that the shakedown is already under way.
More likely, steps to rein in emissions will be too little, too late -- and the world will have to brace for the loss of reefs. In Southeast Asia, says Hoegh-Guldberg, the threat of millions of people losing their livelihoods must be factored into policy planning. Coastal dwellings throughout the tropics will have to be strengthened against higher waves. Then there is the intangible, aesthetic deprivation if coral reefs wither and wink out. "Without their sheer beauty," Hughes says, "the world would be an impoverished place."
Copyright 2007 American Association for the Advancement of Science
From: New York Times
SCIENTISTS SAY CARBON DIOXIDE IS TURNING THE OCEANS ACIDIC
By Kenneth Chang
Whether or not it contributes to global warming, carbon dioxide is turning the oceans acidic, Britain's leading scientific organization warned yesterday.
In a report by a panel of scientists, the organization, the Royal Society, said the growing acidity would be very likely to harm coral reefs and other marine life by the end of the century.
"I think there are very serious issues to be addressed," the panel's chairman, Dr. John Raven of the University of Dundee in Scotland, said in an interview. "It will affect all organisms that have skeletons, shells, hard bits that are made of calcium carbonate."
The 60-page report was timed to influence next week's Group of 8 economic summit meeting. Prime Minister Tony Blair of Britain, president of the group this year, has been calling for strong action to limit climate change.
Unlike forecasts of global warming, which are based on complex and incomplete computer models, the chemistry of carbon dioxide and seawater is simple and straightforward.
The burning of fossil fuels by cars and power plants releases more than 25 billion metric tons of carbon dioxide into the air each year. Roughly a third of that is absorbed by the oceans, where the gas undergoes chemical reactions that produce carbonic acid, which is corrosive to shells.
"That's indisputable," Dr. Raven said. "I don't think anyone can get around that. It's really rock-solid high school chemistry."
The pH scale, which measures the concentration of hydrogen, runs from 1, the most acidic and highest concentration of ions, to 14, the most alkaline, with almost no ions. Ocean water today is somewhat alkaline, at 8.1, about 0.1 lower than at the start of the Industrial Revolution two centuries ago.
But like the magnitude scale of earthquakes, one unit on the pH scale reflects a change of a factor of 10. The 0.1 pH change means there are now 30 percent more hydrogen ions in the water.
Depending on the rate of fossil fuel burning, the pH of ocean water near the surface is expected to drop to 7.7 to 7.9 by 2100, lower than any time in the last 420,000 years, the Royal Society report said.
Dr. Patrick J. Michaels, a senior fellow in environmental studies at the Cato Institute, the libertarian research group based in Washington that is skeptical that global warming will cause serious environmental harm, pointed out that carbon dioxide levels in the atmosphere had been higher for 90 million of the last 100 million years.
But Dr. Ken Caldeira, a research scientist at the Carnegie Institution's Department of Global Ecology in Stanford, Calif., and a member of the Royal Society panel, said the difference was that the current carbon dioxide release was occurring quickly, over just two centuries. In the past, water from the deeper ocean would have had time to mix, diluting the effect of the carbon dioxide. "If we put it out over a few hundred thousand years, we'd have nothing to worry about," he said.
The pH change is likely to slow the rate of growth of coral reefs, which are already suffering from warmer temperatures and pollution, the report said.
"By mid-century, 2050-ish, we will probably see noticeable gaps within coral reefs," Dr. Raven said. "Any weakening of their skeleton can make them more prone to storm events."
The increased acidity could also reduce populations of plankton with calcium carbonate shells, disrupting the food chain and hurting some fisheries, the scientists said.
Copyright 2005 The New York Times Company
From: Seattle Times
RESEARCHERS SEE 'MASSIVE CHANGES' IN THE OCEANS
By Hal Bernton; Seattle Times staff reporter
Carbon dioxide emissions have increased acidity levels of the oceans by 30 percent and in the decades ahead will create new risks for coral, zooplankton and other creatures that help support the North Pacific fisheries, according to researchers who gathered Monday at the University of Washington.
In a two-day workshop that ends today, these scientists are reviewing what is known about this grim corner of climate change and brainstorming ways to measure and assess the threats to a marine ecosystem that yields North America's largest seafood harvests.
The acidification is caused by the ocean's absorption of carbon dioxide produced by fossil-fuel combustion. Currently, this is about 2 billion tons of the gas each year. As this gas dissolves, it sets off a chemical reaction that produces carbonic acid, which in high-enough concentrations can erode protective shells and other structures of some sea creatures.
"We have significant changes in chemistry," said Richard Feely, a Seattle-based National Oceanic and Atmospheric Administration oceanographer who helped to organize the conference. "And if we project over time... we are talking about massive changes that will take place."
Some of the most acidic waters are found in the North Pacific, which has absorbed more carbon dioxide than tropical oceans. The North Pacific appears to be more acidic because it is colder than tropical oceans, which enables it to absorb more carbon, and because it has older, more carbon-rich water than the North Atlantic.
In some areas of the North Pacific -- at depths ranging from about 300 to more than 1,000 feet -- researchers already have detected a kind of saturation point where acidity causes shells to disintegrate faster than they can grow. This contrasts to the North Atlantic, where the saturation point typically is at depths that exceed 7,500 feet, according to Feely.
By the end of the century, these North Pacific saturation zones are expected to expand and extend into much shallower waters. Last year, Feely helped measure the acidity in these zones, and in the years ahead he will start to check the acidity levels of the most productive fishing zone: the Bering Sea.
Researchers also are starting to understand the expanding saturation zones' possible effects on sea life.
For example, there are some 200 species of coccolithophores, phytoplankton that play an important role in the food chain, according to Victoria Fabry, an oceanographer at California State University at San Marcos. So far, only six of those species have been exposed to the higher acid levels of the saturation zone. They showed markedly different responses that ranged from no effect to a 66 percent decline in the calcification process that builds shells.
Fabry also has studied pteropods, tiny mollusks less than an inch long that are an important food source for pink salmon and are susceptible to increased acidity. These pteropods migrate between shallower and deeper waters. So, in some areas they may already swim -- at least briefly -- in carbon-dioxide-saturated waters.
"The bottom line is we really don't know" the long-term effects on the pteropods and how that might affect the salmon, Fabry said.
Another big question mark is the fate of corals.
In tropical areas, researchers expect major reefs to reach a kind of tipping point around 2060. By then, coral organisms may not be able to adapt fast enough, and reef systems will crash or be seriously degraded, according to Chris Langdon, a University of Miami researcher who spoke at the conference.
Much less is known about the deep-sea corals of the North Pacific, which are vital habitat for rockfish, cod and many other commercially important fish species.
These are soft corals, found at much shallower depths than the coldwater hard corals of the North Atlantic that form vast reefs. Some researchers theorize that the differences may reflect the greater natural acidity of the older North Pacific waters, which limited the kinds of coral that could evolve.
But at what point would these soft corals suffer from ocean acidity?
"There is no research that anyone is doing on this, and we need this," said John Guinotte, a researcher with the Marine Conservation Biology Institute.
Hal Bernton: 206-464-2581
Copyright (c) 2007 Seattle Times Company
From: Duluth News-Tribune (MN)
OCEANS GROWING MORE ACIDIC, THREATENING CORAL REEFS
By Juliet Eilperin, Washington Post
The escalating level of carbon dioxide in the atmosphere is making the world's oceans more acidic, government and independent scientists say. They warn that by the end of the century, the trend could decimate coral reefs and creatures that underpin the sea's food web.
Although scientists and some politicians have just begun to focus on the question of ocean acidification, they describe it as one of the most pressing environmental threats facing the Earth.
"It's just been an absolute time bomb that's gone off both in the scientific community and ultimately, in our public policymaking," said Rep. Jay Inslee, D-Wash., who received a two-hour briefing on the subject in May with five other House members. "It's another example of when you put gigatons of carbon dioxide into the atmosphere, you have these results none of us would have predicted."
Thomas Lovejoy, president of the H. John Heinz III Center for Science, Economics and the Environment, has rewritten his new book's paperback version to highlight the threat of ocean acidification. "It's the single most profound environmental change I've learned about in my entire career," he said last week.
A coalition of federal and university scientists will issue a report Wednesday describing how carbon dioxide emissions are, in the words of a news release from the National Center for Atmospheric Research and the National Oceanic and Atmospheric Administration, "dramatically altering ocean chemistry and threatening corals and other marine organisms that secrete skeletal structures."
For decades, scientists have viewed the ocean's absorption of carbon dioxide as an environmental plus, because it mitigates the effects of global warming. But by taking up one-third of the atmosphere's carbon dioxide -- much of which stems from exhaust from automobiles, power plants and other industrial sources -- the ocean is transforming its pH level.
The pH level, measured in "units," is a calculation of the balance of a liquid's acidity and its alkalinity. The lower a liquid's pH number, the higher its acidity; the higher the number, the more alkaline it is. The pH level for the world's oceans was stable between 1000 and 1800, but has dropped one-tenth of a unit since the Industrial Revolution, according to Christopher Langdon, a University of Miami marine biology professor.
Scientists expect ocean pH levels to drop by another 0.3 units by 2100, which could seriously damage marine creatures who need calcium carbonate to build their shells and skeletons. Once absorbed in seawater, carbon dioxide forms carbonic acid and lowers the ocean's pH, making it harder for corals, plankton and tiny marine snails (called pteropods) to form their body parts.
Ken Caldeira, a chemical oceanographer at Stanford University who briefed lawmakers along with NCAR marine ecologist Joan Kleypas, said the ocean is more acid than it has been for "many millions of years."
"What we're doing in the next decade will affect our oceans for millions of years," Caldeira said. "CO2 levels are going up extremely rapidly, and it's overwhelming our marine systems."
Stanford University marine biologist Robert Dunbar has studied the effect of increased carbon dioxide on coral reefs in Israel and Australia's Great Barrier Reef. "What we found in Israel was the community is dissolving," Dunbar said.
Plankton and marine snails are critical to sustaining marine species such as salmon, redfish, mackerel and baleen whales.
"These are groups everyone depends on, and if their numbers go down there are going to be reverberations throughout the food chain," said John Guinotte, a marine biologist at the Marine Conservation Biology Institute. "When I see marine snails' shells dissolving while they're alive, that's spooky to me."
Copyright (c) 2006 Duluth News-Tribune
From: Financial Times (London, UK)
THE SOUTHERN OCEAN IS APPROACHING ITS LIMIT FOR CARBON ABSORPTION
By Clive Cookson
Recent climate change has weakened one of the earth's most important natural carbon "sinks", according to a four-year international study published today.
An increase in winds over the southern ocean, caused by man-made global warming and ozone depletion, has led to a release of stored carbon dioxide from the ocean into the atmosphere and is preventing further absorption of the greenhouse gas.
The study was undertaken by the University of East Anglia, British Antarctic Survey and the Max-Planck Institute for Biogeochemistry in Germany and is published in the online edition of the journal Science. It suggests stabilising carbon dioxide levels in the atmosphere will be even more difficult than previously believed.
To make matters worse, acidification of the southern ocean as a result of dissolved carbon dioxide is likely to reach dangerous levels before the projected date of 2050.
Corinne Le Quere, the study leader, said: "This is the first time that we've been able to say climate change itself is responsible for the saturation of the southern ocean sink. This is serious. All climate models predict that this kind of 'feedback' will continue and intensify during this century."
Copyright The Financial Times Limited 2007
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