Joseph Coleman, Associated Press Yahoo News 8 Dec 07;
The concept, however, has problems. Skeptics, for instance, say that trees are effective for carbon storage because they can last for many years, while seaweed is cultivated and harvested in cycles of only months, meaning the storage will be hard to measure or control.
Slimy, green and unsightly, seaweed and algae are among the humblest plants on earth. A group of scientists at a climate conference in Bali say they could also be a potent weapon against global warming, capable of sucking damaging carbon dioxide out of the atmosphere at rates comparable to the mightiest rain forests.
"The ocean's role is neglected because we can't see the vegetation," said Chung Ik-kyo, a South Korean environmental scientist. "But under the sea, there is a lot of seaweed and sea grass that can take up carbon dioxide."
The seaweed research, backed by scientists in 12 countries, is part of a broad effort to calculate how much carbon is being absorbed from the atmosphere by plants, and figure out ways to increase that through reforestation and other steps.
Such so-called "carbon sinks" are considered essential to controlling greenhouse gases, which trap heat in the atmosphere and are blamed for global warming.
The conference in Bali is aimed at launching two-year negotiations for a new global warming pact to replace the Kyoto Protocol when it expires in 2012, and using the earth's natural resources to remove carbon from the air is a major topic of discussion.
While the lion's share of attention to carbon sinks has been on forests, the seaweed scientists say the world should look to the sea, where nearly 8 million tons of seaweed and algae are cultivated every year.
That solution is a largely Asian one and it's not without complications.
China is by far the world's largest producer of seaweed, followed by South Korea and Japan. The Asia-Pacific — where seaweed is used in soups, sushi and salads — accounts for 80 percent of global production.
Proponents say seaweed and algae's rapid rate of photosynthesis, the process of turning carbon dioxide and sunlight into energy and oxygen, is a top factor in its effectiveness in carbon absorption.
Some types of seaweed can grow three or four meters (yards) long in only three months. Lee Jae-young, with South Korea's fisheries ministry, said some seaweeds can absorb five times more carbon dioxide than terrestrial plants.
"These are very productive ecosystems, they're drawing down a lot of carbon," said John Beardall, with Australia's Monash University.
South Korea and Japan are leaders in the research. Last year, Seoul approved a US$1.5 million (euro1 million) a year project to investigate the possibilities. The Japanese government and a group of companies are also looking into setting up a huge cultivation area in the waters off the country's western coast.
In a presentation on the sidelines of the Bali conference on Friday, Beardall argued that more efficient cultivation methods could greatly boost production in nations with long coastlines, such as the Philippines.
In addition to storing carbon, seaweed can be used to produce clean-burning biofuels, thereby making sure that the carbon isn't simply recycled back into the air.
"Feeding algae to people will only release the CO2 back into the atmosphere again," said Beardall. "It's not carbon sequestration."
The concept, however, has problems. Skeptics, for instance, say that trees are effective for carbon storage because they can last for many years, while seaweed is cultivated and harvested in cycles of only months, meaning the storage will be hard to measure or control.
"It depends on how long you keep the materials," said I Nyoman Suryadiputra of Wetlands International. "Because if it is decomposed in a month, the carbon dioxide will go back into the atmosphere."
Other obstacles remain. Some critics wonder if removing sea water from the seaweed as it's converted to fuel would require a large amount of energy that reduces its environmental benefits, though supporters say sun-drying could be used.
The environmental impact of rapid expansion of seaweed farms has also not been thought out, scientists concede. Huge floating farms could complicate fishing, shipping and other maritime activities.
Chung acknowledged the idea was in its infancy.
"In terms of ball games, we are just in the bullpen," he said, "not the main game yet."
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