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Archive for the ‘Dead Zones’ Category

ScienceDaily, June 19, 2010

The first comprehensive synthesis on the effects of climate change on the world’s oceans has found they are now changing at a rate not seen for several million years.

In an article published June 18 in Science magazine, scientists reveal the growing atmospheric concentrations of man-made greenhouse gases are driving irreversible and dramatic changes to the way the ocean functions, with potentially dire impacts for hundreds of millions of people across the planet.

The findings of the report emerged from a synthesis of recent research on the world’s oceans, carried out by two of the world’s leading marine scientists, one from The University of Queensland in Australia, and one from The University of North Carolina at Chapel Hill, in the USA.

Professor Ove Hoegh-Guldberg, lead author of the report and Director of The University of Queensland’s Global Change Institute, says the findings have enormous implications for mankind, particularly if the trend continues.

He said that the Earth’s ocean, which produces half of the oxygen we breathe and absorbs 30% of human-generated CO2, is equivalent to its heart and lungs. “Quite plainly, the Earth cannot do without its ocean. This study, however, shows worrying signs of ill health.

“It’s as if the Earth has been smoking two packs of cigarettes a day!”

He went on to say, “We are entering a period in which the very ocean services upon which humanity depends are undergoing massive change and in some cases beginning to fail,” says Prof. Hoegh-Guldberg. “Further degradation will continue to create enormous challenges and costs for societies worldwide.”

He warned that we may soon see “sudden, unexpected changes that have serious ramifications for the overall well-being of humans,” including the capacity of the planet to support people. “This is further evidence that we are well on the way to the next great extinction event.”

The “fundamental and comprehensive” changes to marine life identified in the report include rapidly warming and acidifying oceans, changes in water circulation and expansion of dead zones within the ocean depths.

These are driving major changes in marine ecosystems: less abundant coral reefs, sea grasses and mangroves (important fish nurseries); fewer, smaller fish; a breakdown in food chains; changes in the distribution of marine life; and more frequent diseases and pests among marine organisms.

Report co-author, Dr John F. Bruno, an Associate Professor at The University of North Carolina, says greenhouse gas emissions are modifying many physical and geochemical aspects of the planet’s oceans, in ways “unprecedented in nearly a million years.” “This is causing fundamental and comprehensive changes to the way marine ecosystems function,” Dr Bruno said.

“We are becoming increasingly certain that the world’s marine ecosystems are approaching tipping points. These tipping points are where change accelerates and causes unrelated impacts on other systems, the results of which we really have no power or model to foresee.”

The authors conclude: “These challenges underscore the urgency with which world leaders must act to limit further growth of greenhouse gases and thereby reduce the risk of these events occurring. Ignoring the science is not an option.”

In their study, the researchers sought to address a gap in previous studies that have often overlooked the affects of climate change on marine ecosystems, due to the fact that they are complex and can be logistically difficult to study.

According to leading US marine scientist, the University of Maine’s School of Marine Services Professor Robert S. Steneck, the study provides a valuable indicator of the ecological risk posed by climate change, particularly to coastal regions.

“While past studies have largely focused on single global threats such as ‘global warming’, Hoegh-Guldberg and Bruno make a compelling case for the cumulative impacts of multiple planet-scale threats,” Prof. Steneck said.

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HELON ALTONN, Honolulu Star Bulletin, December 27, 2009

The ocean is becoming a noisier place due to increased greenhouse gas emissions, California and Hawaii scientists report.

Rising atmospheric carbon dioxide absorbed by the oceans not only has increased seawater acidity but has affected its acoustics—making it more transparent to low-frequency sound, the scientists said in a study published in the journal Nature Geoscience.

Scientists said seawater sound absorption will drop by up to 70% this century.

“It was surprising to us,” said Richard Zeebe, an associate professor of oceanography at the University of Hawaii School of Ocean and Earth Science and Technology.

Increased atmospheric carbon dioxide dissolved in the oceans increases acidity, or hydrogen ion concentration, and as the acidity rises, it lowers the seawater pH (a measure of acidity), researchers said.

“Certain chemical compounds in the ocean absorb sound and affect sound propagation,” Zeebe said. “Frequencies can get louder and more intense, depending on the chemistry.”

Not all frequencies will be affected, he said, explaining pH changes mostly affect sounds in the lower frequency range.

SOEST researcher Tatiana Ilyina said the pH of surface seawater will drop by 0.6 units by the year 2100 at the current rate of carbon dioxide emissions, with a one-unit drop of pH representing a tenfold increase of acidity.

“As a result, the absorption of 200 Hz sound would decrease by up to 70%,” she said, noting the middle C of the piano is tuned to 261.6 Hz. Sound around that frequency is produced by natural phenomena such as rain, wind and waves, and marine mammals and manmade activities, she said.

Naval, commercial and scientific activities use low-frequency sound and marine mammals rely on low-frequency sound to find food and mates, the scientists said.

“As a result, ocean acidification may not only affect organisms at the bottom of the food chain by reducing calcification in plankton and corals, but also higher tropic-level species, such as marine mammals, by lowering sound absorption in the ocean,” they said.

Zeebe said: “The consequences of these changes on marine mammals is not well known at the moment. There is a lot of background noise in the ocean generated by humans—ship noise, construction, seismic surveys and sonar—and this noise will essentially increase in volume in the ocean in the future.

“If the noise level increases, it can distract species,” he said. “If they’re trying to identify certain sounds in the ocean important for them for reproduction, feeding or something, and if the background noise is increasing, it could essentially cover certain sounds they depend on. This is a possibility.”

Another possibility is that marine mammals may be able to communicate over larger distances in the lower frequency range if sound absorption is decreased because underwater sounds can travel farther than at the surface, he said.

“Also, there are commercial and scientific applications, seismic surveys, that probably will have to take into account that future sound propagation in the ocean will slowly change,” Zeebe said, adding that more study is needed to determine the effects of the ocean acoustics changes.

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Endangered species’ communication critical to survival

ARIEL DAVID, Seattle Post Intelligence, December 8, 2008

Whale-460_980418cThe songs that whales and dolphins use to communicate, orient themselves and find mates are being drowned out by human-made noises in the world’s oceans, U.N. officials and environmental groups said Wednesday.

That sound pollution — everything from increasing commercial shipping and seismic surveys to a new generation of military sonar — is not only confounding the mammals, it also is further threatening the survival of these endangered animals.

Studies show that these cetaceans, which once communicated over thousands of miles to forage and mate, are losing touch with each other, the experts said at a U.N. wildlife conference in Rome.

“Call it a cocktail-party effect,” said Mark Simmonds, director of the Whale and Dolphin Conservation Society, a Britain-based NGO. “You have to speak louder and louder until no one can hear each other anymore.”

An indirect source of noise pollution may also be coming from climate change, which is altering the chemistry of the oceans and making sound travel farther through sea water, the experts said.

Representatives of more than 100 governments are gathered in Rome for a meeting of the U.N.-backed Convention on the Conservation of Migratory Species of Wild Animals.

The agenda of the conference, which ends Friday, includes ways to increase protection for endangered species, including measures to mitigate underwater noise.

Environmental groups also are increasingly finding cases of beached whales and dolphins that can be linked to sound pollution, Simmonds said.

Marine mammals are turning up on the world’s beaches with tissue damage similar to that found in divers suffering from decompression sickness. The condition, known as the bends, causes gas bubbles to form in the bloodstream upon surfacing too quickly.

Scientists say the use of military sonar or seismic testing may have scared the animals into diving and surfacing beyond their physical limits, Simmonds said.

Several species of cetaceans are already listed as endangered or critically endangered from other causes, including hunting, chemical pollution, collisions with boats and entanglements with fishing equipment. Though it is not yet known precisely how many animals are affected, sound pollution is increasingly being recognized as a serious factor, the experts said.

As an example, Simmonds offered two incidents this year that, though still under study, could be linked to noise pollution: the beaching of more than 100 melon-headed whales in Madagascar and that of two dozen common dolphins on the southern British coast.

The sound of a seismic test, used to locate hydrocarbons beneath the seabed, can spread 1,800 miles under water, said Veronica Frank, an official with the International Fund for Animal Welfare. A study by her group found that the blue whale, which used to communicate across entire oceans, has lost 90 percent of its range over the past 40 years.

Despite being the largest mammal ever to inhabit Earth, the endangered blue whale still holds mysteries for scientists.

“We don’t even know where their breeding grounds are,” Simmonds said. “But what’s most important is that they need to know where they are.”

Other research suggests that rising levels of carbon dioxide are increasing the acidity of the Earth’s oceans, making sound travel farther through sea water.

The study by the Monterey Bay Aquarium Research Institute in the United States shows the changes may mean some sound frequencies are traveling 10% farther than a few centuries ago. That could increase to 70% by 2050 if greenhouse gases are not cut.

However, governments seem ready to take action, said Nick Nutall, a spokesman for the U.N. Environment Program, which administers the convention being discussed in Rome. The conference is discussing a resolution that would oblige countries to reduce sound pollution, he said.

Measures suggested include rerouting shipping and installing quieter engines as well as cutting speed and banning tests and sonar use in areas known to be inhabited by the animals.

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RICHARD MORGAN, The New York Times, September 2, 2008

TOOLIK FIELD STATION, Alaska — As Anne Giblin was lugging four-foot tubes of Arctic lakebed mud from her inflatable raft to her nearby lab this summer, she said, “Mud is a great storyteller.”

Dr. Giblin, a senior scientist at the Marine Biological Laboratory in Woods Hole, Mass., is part of the Long Term Ecological Research network at an Arctic science outpost here operated by the University of Alaska at Fairbanks.

Public discussion of complicated climate change is largely reduced to carbon: carbon emissions, carbon footprints, carbon trading. But other chemicals have large roles in the planet’s health, and the one Dr. Giblin is looking for in Arctic mud, one that a growing number of other researchers are also concentrating on, is nitrogen.

In addition to having a role in climate change, nitrogen has a huge, probably more important biological impact through its presence in fertilizer. Peter Vitousek, a Stanford ecologist whose 1994 essay put nitrogen on the environmental map, co-authored a study this summer in the journal Nature that put greater attention on the nitrogen cycle and warned against ignoring it in favor of carbon benefits.

For example, Dr. Vitousek said in an interview, “There’s a great danger in doing something like, oh, overfertilizing a cornfield to boost biofuel consumption, where the carbon benefits are far outweighed by the nitrogen damage.”

Soon after Dr. Vitousek’s report, the journal Geophysical Research Letters branded as a “missing greenhouse gas” nitrogen trifluoride, which is used in production of semiconductors and in liquid-crystal displays found in many electronics. According to the report, it causes more global warming than coal-fired plants. Nitrogen trifluoride, which is not one of the six gases covered by the Kyoto Protocol, the celebrated international global warming accord, is about 17,000 times more potent than carbon dioxide. Its estimated worldwide release into the atmosphere this year is equivalent to the total global-warming emissions from Austria.

“The nitrogen dilemma,” Dr. Vitousek added, “is not just thinking that carbon is all that matters. But also thinking that global warming is the only environmental issue. The weakening of biodiversity, the pollution of rivers, these are local issues that need local attention. Smog. Acid rain. Coasts. Forests. It’s all nitrogen.”

Dr. Vitousek’s summer report followed a similar account in May in the journal Science by James N. Galloway, an environmental sciences professor at the University of Virginia and a former chairman of the International Nitrogen Initiative, a group of scientists pushing for smarter use of nitrogen.

Dr. Galloway is developing a universal calculator for individual nitrogen footprints. “It’s Goldilocks’s problem,” he said in an interview. “Reactive nitrogen isn’t a waste product. We need it desperately. Just not too much and not too little. It’s just more complicated than carbon.” He continued, “But we’re not going to get anywhere telling people this is simple or easy.”

Dr. Giblin of Woods Hole spent the summer at the field station here, midway between the Arctic Circle and the Arctic Ocean, researching the nitrogen content of lakebed sediment — not the inert nitrogen that makes up 80& of air, the reactive nitrogen that Dr. Galloway referred to. In forms like nitric acid, nitrous oxide, ammonia and nitrate it plays a variety of roles.

Nitrogen is part of all living matter. When plants and animals die, their nitrogen is passed into soil and the nitrogen in the soil, in turn, nourishes plants on land and seeps into bodies of water. Dr. Giblin is pursuing her research because as the Arctic warms, the tundra’s permafrost will thaw, and the soil will release carbon and nitrogen into the atmosphere.

When an ecosystem has too much nitrogen, the first response is that life blossoms. More fish, more plants, more everything. But this quickly becomes a kind of nitrogen cancer.  Waters cloud and are overrun with foul-smelling algae blooms that can cause toxic “dead zones.” Scientists call this process eutrophication, but the laymen’s translation is that the water gets mucked up beyond all recognition. A recent such plague bedeviled China when its Yellow Sea was smothered in algae at Qingdao, the planned site of Olympic sailing events this summer. More than mere inconvenience, such problems routinely threaten many coastal areas and riverside communities.

Nancy Rabalais, executive director of the Louisiana Universities Marine Consortium, is known as Queen of the Dead Zone. She cruises around the Gulf of Mexico every summer in the research vessel Pelican to look for damage from nitrogen-rich river flows into the gulf. This year, she expects a dead zone that will beat the Massachusetts-size 8,500-square-mile bloom of 2002.

One of the problems, Dr. Rabalais said, is that the Mississippi River involves so many communities that it requires stronger federal guidance, which she said was not a part of the Bush administration’s policies. She is part of a national research committee financed by the Environmental Protection Agency and run by the National Academies of Science, but, she said, “it’s so much talk and not enough action.”

She continued: “Because you’re not just going up against the agribusiness lobby, but also the livelihood of farmers. It’s not exactly popular in the Midwest.”

Fertilizer use is largely inefficient. With beef, only about 6% of nitrogen used in raising cows ends up in their meat; the rest leeches out into air or water supplies. With pork, it is 12%; chicken, 25%. Milk, eggs and grain have the highest efficiency, about 35%, or half of what, in the metric of report cards, is a C-minus.

“Look,” she said, “you just can’t have all these states and all these communities knowingly overfertilizing their land because they want a bumper crop every year. That’s just all kinds of bad. But Des Moines, for example, is willing to filter their drinking water to an extra degree just to be able to flood their water supply with more-than-normal levels of fertilizer.”

Reactive nitrogen competes with greenhouse gases that have greater public awareness. “But it’s like looking at malaria and AIDS in Africa,” Dr. Rabalais said. “They’re both problems. And they both need vigilant attention.”

Environmentalists face the puzzle of how to deal with multiple problems at once. And some worry that after the hard-fought campaign spotlighting carbon, turning to focus on nitrogen could upset that momentum.

The tension can plague even the most informed and articulate campaigners. “One of the many complexities that complicate the task I’ve undertaken is complexity,” said Al Gore, the former vice president who won a Noble Peace Prize for his environmental work. Mr. Gore added, “Look, I can start a talk by saying, ‘There are 14 global warming pollutants, and we have a different solution for addressing each of them.’ And it’s true. But you start to lose people.”

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