Tiny shrimp leave giant carbon footprint: scientist

AFP Dawn.com 19 Feb 12;

VANCOUVER: Measured by environmental impact, a humble shrimp cocktail could be the most costly part of a typical restaurant meal, scientists said Friday.

If the seafood is produced on a typical Asian fish farm, a 100-gram (3.5 ounce) serving “has an ecosystem carbon footprint of an astounding 198 kilograms (436 pounds) of CO2,” biologist J. Boone Kauffman said.

A one-pound (454-gram) bag of frozen shrimp produces one ton of carbon dioxide, said Kauffman, who is based at Oregon State University and conducts research in Indonesia.

He told a meeting of the American Association for the Advancement of Science that he developed the comparison to help the public understand the environmental impact of land use decisions.

Kauffman said 50 to 60 percent of shrimp farms are located in tidal zones in Asian countries, mostly on cleared mangrove forests.

“The carbon footprint of the shrimp from this land use is about 10-fold greater than the land use carbon footprint of an equivalent amount of beef produced from a pasture formed from a tropical rainforest,” wrote Kauffman in a paper released to AFP, not including emissions from farm development, feeds, supplements, processing, storing and shipping.

The farms are inefficient, producing just one kilogram (2.2 pounds) of shrimp for 13.4 square meters (five square miles) of mangrove, while the ponds created are abandoned in just three to nine years because disease, soil acidification and contamination destroy them, he wrote.

After abandonment, the soil takes 35 to 40 years to recover, he said.

Emily Pidgeon of Conservation International said intact mangrove forests are of value in protecting the coastal ecosystems and communities against storms and tsunamis, such as the Indian Ocean tsunami in 2004 that killed some 230,000 people.

The problem, she said, is the value of intact mangroves is hard to measure, and most of the shrimp farms are in impoverished areas that cannot easily afford conservation.

“It’s difficult to find the financing to do it, or the political will,” she said, adding Kauffman’s carbon measurements provide another argument in favor of protection.

The catchy shrimp cocktail estimate is part of the relatively new field in science and economics called ecosystem services, which uses models to measure the value to human communities, in economic terms, of forests, grassland, waterways and even the air.
“To present how deforestation and land cover change contribute to global climate change in a comprehensible manner, we change the scale of greenhouse gas emissions from global to personal scales,” wrote Kauffman.

The Carbon Footprint of a Shrimp Cocktail
Erik Stokstad Science Now 17 Feb 12;

VANCOUVER, CANADA—In many parts of Latin America and Asia, large swaths of coastal mangrove forests have been cut down and turned into shrimp farms. Not only does this deforestation destroy habitat for birds and cause other ecological problems, but it also releases a large amount of the carbon stored in mangrove soil—so much, in fact, that the shrimp end up having a sizable carbon footprint, according to calculations presented here today at the annual meeting of the American Association for the Advancement of Science (which publishes ScienceNOW).

To get a handle on how much carbon dioxide is represented by shrimp, ecologist Boone Kauffman of Oregon State University in Corvallis made some estimates based on typical shrimp farms in southeast Asia. He looked at farms that are relatively large and not particularly productive, with harvests yielding 50 to 500 kilograms of shrimp per hectare. These farms, which make up about half of those in the world, only last for 5 years or so before the buildup of sludge in the ponds and the acid sulfate soil renders them unfit for shrimp. “It's the equivalent of slash-and-burn agriculture,” Kauffman said. (Other types of shrimp farms are more efficient and not located in mangrove forests.)

Drawing on other studies, Kauffman estimated that 401 metric tons of carbon are emitted to the atmosphere when a hectare of mangrove is converted to a shrimp farm, which is equivalent to 1472 tons of carbon dioxide. Over the average 5-year life span of a farm, a farmer will typically harvest about 1659 kilograms of shrimp. So a 100-gram shrimp cocktail represents an “astonishing” 198 kilograms of carbon dioxide from the loss of the mangrove, Kauffman said, the equivalent of burning 90 liters of gasoline. The carbon intensity of shrimp from deforested mangroves is 10 times greater than that of beef grown in deforested Amazonian rain forest, according to other unpublished calculations Kauffman has made. The calculations don't include the energy involved in feeding, processing, and transporting the shrimp.

“The shrimp cocktail is a good example of how carbon cost associated with mangrove degradation way outweighs the actual product that is produced,” Emily Pidgeon of Conservation International told the audience at a session entitled “Blue Carbon, Green Opportunities: Innovative Solutions To Protect Coastal Ecosystems.” So, how much would it cost to prevent mangroves from being turned into shrimp farms? Based on his calculations, Kauffman says that compensating farmers for not growing shrimp would mean that each ton of carbon kept intact in mangrove soil would cost about $4.50. “That's well within the range of carbon markets,” Kauffman said.

At the moment, these carbon markets only trade in credits for terrestrial ecosystems; for example, keeping a certain amount of forest intact in order to offset a ton of carbon dioxide emitted by burning fossil fuels. At the session, Carolyn Ching of the VCS Association—a firm that creates accounting standards for carbon credits—described progress in devising the first carbon credit program for mangroves and other wetlands, which could provide funds for their conservation and restoration. Ching suggested the system could be finalized and running as early as September: “We see carbon finance as one of the potential mechanisms for addressing wetlands conservation.”