New Kind Of Undersea Eruption Defined: 'Neptunian'

ScienceDaily - Two Australian researchers have defined a newly recognized kind of explosive eruption, termed "neptunian," that is restricted to seafloor volcanoes.

Sharon R. Allen and Jocelyn McPhie, of the School of Earth Sciences and Centre of Excellence in Ore Deposits, at the University of Tasmania in Hobart, Tasmania, describe their work in a new article published in the journal Geology.

These eruptions are sustained and driven by gas exsolved from magma. The explosions inject large volumes of hot pumice clasts into the seawater above the vent. The hot pumice clasts rapidly absorb water and sink, forming density currents that flow across the seafloor.

Vast areas of the modern seafloor are covered by these pumice-rich neptunian deposits. Neptunian eruptions differ dramatically from magmatic-gas-driven explosive eruptions on land, reflecting the important influence of confining pressure and the higher heat capacity, density, and viscosity of water compared to air.

Source: http://www.sciencedaily.com/releases/2009/06/090630204755.htm

Global Sunscreen Won't Save Corals

ScienceDaily — Emergency plans to counteract global warming by artificially shading the Earth from incoming sunlight might lower the planet's temperature a few degrees, but such "geoengineering" solutions would do little to stop the acidification of the world oceans that threatens coral reefs and other marine life, report the authors of a new study in the journal Geophysical Research Letters. The culprit is atmospheric carbon dioxide, which even in a cooler globe will continue to be absorbed by seawater, creating acidic conditions.

"There would be a slight reduction in this problem, because land plants would be expected to be able to grow more vigorously in a high CO2, but cool world," says Ken Caldeira of the Carnegie Institution's Department of Global Ecology, a co-author of the study with lead author Damon Matthews of Concordia University, Canada, and Carnegie geochemist Long Cao. Land plants and soils would hold onto more carbon in this scenario, so less would find its way into the oceans. "However this expansion of the land biosphere, while it's a slight help to ocean acidification is not enough to make a big difference."

A widely-discussed proposal for countering warming with geoengineering involves injecting small, reflective particles into the upper atmosphere. This would partially block incoming sunlight before it reached the Earth's surface, lowering global temperatures just as volcanic ash from the Mount Pinatubo did following its eruption in 1991. But critics have warned that such a scheme might also alter rainfall patterns, damage the planet's ozone layer, or have other unexpected effects.

Until the current study, which used a computer model of the Earth's climate system and biosphere to simulate the effect of geoengineering on climate and the ocean's chemistry, the potential impact of such a scheme on ocean acidification had never been calculated. In the simulations, reduced sunlight cooled the planet as expected,,and it also slightly slowed the rise in atmospheric carbon dioxide, as more carbon was absorbed by natural sinks. But this slight change was not enough to significantly mitigate ocean acidification.

Ocean acidification rivals global warming as a threat to marine ecosystems, especially coral reefs, which need to be surrounded with mineral-saturated water in order to grow. Rising levels of carbon dioxide make seawater more acidic, leading to lower mineral saturation. Recent research has indicated that continued carbon dioxide emissions will cause coral reefs to begin dissolving within a few decades, putting the survival of these ecosystems at extreme risk.

Geoengineering's minimal effect on ocean acidification adds another factor to the debate over the advisability of intentionally tampering with the climate system. Some see geoengineering as a possibly necessary response to the prospect of devastating climate change caused by increased human emission of greenhouse gases. Others see it as reckless tinkering with the planet's complex and finely tuned climate system that could do more harm than good.

"Geoengineering approaches come with all sorts of risks," says Caldiera. "It is important we learn about the the full set of these risks and all of their implications." He considers deep cuts in human emissions of carbon dioxide to be the most effective safeguard against a global environmental crisis. "One of the good reasons to prefer CO2 emissions reductions over geoengineering is that CO2 emissions reductions will protect the oceans from the threat of ocean acidification, whereas these geoengineering options will not."

Source: http://www.sciencedaily.com/releases/2009/06/090616133938.htm

Young Asians saying no to shark fin soup

Consumption of delicacy drops as wildlife conservation movement gains momentum

Singaporean groom Han Songguang took his campaign to stop consumption of one of Asia's top delicacies to a new level when he placed postcards of a dead shark on each guest's seat at his own wedding banquet.

Instead of shark's fin soup, a must at many ethnic Chinese wedding banquets, Han offered his guests lobster soup.

"If we can do our part to save X number of sharks ... why not?" said Han, a geography teacher, who married a diving enthusiast in December.

Wildlife conservationists, who have long railed against the popularity of shark fin soup, are finally seeing signs that consumption is dropping as young Asians become aware of the environmental impact of this much-prized dish.

Added to that is the global financial crisis, which is causing Asians to tighten their belts and either cut down on visits to restaurants or order more frugally from menus.

A symbol of wealth and status in Chinese culture, shark fin soup has long been an essential part of banquet celebrations for weddings and to welcome the Lunar New Year.

Until recently, only the rich could afford the soup. But demand has soared in recent years, hand-in-hand with rising affluence in East Asia. The quantity of shark fins demanded, around 800,000 metric tonnes a year, has caused a sharp decline in shark numbers. About 20 per cent of all shark species are now endangered.

Wildlife conservationists also decry the killing of sharks through "finning," whereby the fins are cut off and the live shark is tossed back into the sea. Unable to swim properly, the shark suffocates or is killed by predators.

"Today we have incredible access to information. It has become much harder to say, 'I didn't know,' " said Glenn Sant, marine program leader of the British wildlife group Traffic.

He urged young Asians to take a stand and say: " 'It shouldn't be an insult not to put shark fin on our wedding menu.' "

Despite efforts to ban "finning," environmentalists say it is still carried out across the region as fishermen want the valuable fin but don't want to store the rest of the shark, as its flesh fetches low prices at fish markets.

As young Asians such as Han take a stand against shark fin soup, environmentalists hope for a long-term drop in consumption.

Still, there is a robust market of older consumers who demand the soup at auspicious events.

"Students and people in their 20s wouldn't go to a shark eatery, and $15 for a dish is no cheap price," said Joyce Wu, program officer with Traffic.

Indonesia, Malaysia, Taiwan, Thailand and China, including Hong Kong, are all major shark fin consumers, according to a Traffic report. Trade in shark products was worth $310 million US in 2005, with fins 40 per cent of the total, the report says.

Those numbers are coming down as younger consumers eschew the delicacy of their parents.

Worldwide shark consumption dropped from a peak of 897,000 metric tonnes in 2003 to 758,000 in 2006, according to the UN Food and Agriculture Organization. Fins make up an increasingly small percentage of the total, Traffic says.

Sharks live a long time, said Yvonne Sadovy, a biology professor at the University of Hong Kong. "They have a low reproductive rate. In in other words, they produce just a few young every year or every few years. So you just can't take a lot."

Tastes have changed along with awareness for young Asians. Shang-kuan Liang-chi, a National Taiwan University student who has tried the crunchy jelly-like dish twice at formal events, prefers other food and avoids a shark fin restaurant near campus. "University students never go in there," he said.

Even chefs are hoping to turn the tide. At Singapore's Annual Chefs' Association dinner, shark fin traditionally served at the occasion was taken off the menu.

"It is much harder to stop serving shark's fin in our restaurants, as the consumers still demand it," said Otto Weibel, a food manager at one of Singapore's top hotels. "However, in our personal capacity, we can make a stand."

Global entertainment giant Disney bowed to pressure from animal rights activists and took the delicacy off its menu when it opened Hong Kong Disneyland in 2005.
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