Betreff: Rachel's #910: Ocean Food Chain Imperiled

Von: Peter Montague

Datum: Thu, 7 Jun 2007 17:02:31 -0400

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Rachel's Democracy & Health News #910

"Environment, health, jobs and justice--Who gets to decide?"

Thursday, June 7, 2007..................Printer-friendly version

www.rachel.org --

 
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Featured stories in this issue...
 
Acidic Oceans Affecting Food Fish
 Thomas Lovejoy, the executive director of the H. John Heinz III
 Center for Science, Economics and the Environment, says acidification
 of the oceans is "the most profound environmental change I've
 encountered in my professional career," and says the consequences for
 ocean life are "shaking the biological underpinnings of civilization."
Climate Change: A Guide for the Perplexed
 How do you talk to skeptics about global warming? Here's a
 science-based response to 26 common myths.
A World Without Corals?
 Besieged by pathogens, predators, and people, the "rainforests of
 the sea" may soon face their ultimate foe: rising ocean acidity driven
 by CO2 emissions, says the American Association for the Advancement of
 Science.
Scientists Say Carbon Dioxide Is Turning the Oceans Acidic
 "I think there are very serious issues to be addressed," said Dr.
 John Raven of the University of Dundee in Scotland, who led a study
 of ocean acidification for the British Royal Society. Increased
 acidity could also reduce populations of plankton with calcium
 carbonate shells, disrupting the food chain, other scientists said.
Researchers See 'Massive Changes' in the Oceans
 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 at University of
 Washingtton.
Oceans Growing More Acidic, Threatening Coral Reefs
 "What we're doing in the next decade will affect our oceans for
 millions of years," says Ken Caldeira, a chemical oceanographer at
 Stanford University. "CO2 levels are going up extremely rapidly, and
 it's overwhelming our marine systems."
The Southern Ocean Is Approaching Its Limit for Carbon Absorption
 In a double whammy, the Southern Ocean has now absorbed so much
 carbon dioxide that is turning acidic, but it is also reaching its
 limit for further absorption -- thus accelerating the buildup of heat-
 trapping gases in the atmosphere.
 
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From: The Daily Green, May 1, 2007
[Printer-friendly version]
 
ACIDIC OCEANS AFFECTING FOOD FISH
 
By Dan Shapley, News Editor
 
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.
 
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From: New Scientist, May 16, 2007
[Printer-friendly version]
 
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.
 
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From: Science (pg. 678), May 4, 2007
[Printer-friendly version]
 
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
 
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From: New York Times, Jul. 2, 2005
[Printer-friendly version]
 
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
 
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From: Seattle Times, Apr. 24, 2007
[Printer-friendly version]
 
'MASSIVE CHANGES,' UNKNOWNS DISCUSSED AT UW CONFERENCE
 
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 7,50