Tuesday, December 1, 2009

Oceans Absorb Less Carbon Dioxide as Marine Systems Change

From: Ben Block, Worldwatch Institute, More from this Affiliate

The oceans are by far the largest carbon sink in the world. Some 93 percent of carbon dioxide is stored in algae, vegetation, and coral under the sea. But oceans are not able to absorb all of the carbon dioxide

released from the burning of fossil fuels. In fact, a recent study suggests that the oceans have absorbed a smaller proportion of fossil-fuel emissions, nearly 10 percent less, since 2000.

The study, published in the current issue of Nature, is the first to quantify the perceived trend that oceans are becoming less efficient carbon sinks. The study team, led by Columbia University oceanographer Samar Khatiwala, measured the amount of human-caused carbon dioxide emissions pumped into the oceans since 1765.

Industrial carbon dioxide emissions have increased dramatically since the 1950s, and oceans have until recently been able to absorb the greater amounts of emissions. Sometime after 2000, however, the rise in emissions and the oceans' carbon uptake decoupled. Oceans continue to absorb more carbon, but the pace appears to have slowed.

The reason is based in part on simple chemistry. Increased concentrations of carbon dioxide have turned waters more acidic, especially nearer to the poles. While carbon dioxide dissolves more readily in cold, dense seawater, these waters are less capable of sequestering the gas as the ocean becomes more acidic. The study revealed that the Southern Ocean, near Antarctica, absorbs about 40 percent of the carbon in oceans.

Article continues: http://www.worldwatch.org/node/6323

Global Salmon Study Shows 'Sustainable' Food May Not Be So Sustainable

From: Science Daily

Popular thinking about how to improve food systems for the better often misses the point, according to the results of a three-year global study of salmon production systems. Rather than pushing for organic or land-based production, or worrying about simple metrics such as "food miles," the study finds that the world can achieve greater environmental

benefits by focusing on improvements to key aspects of production and distribution.

For example, what farmed salmon are fed, how wild salmon are caught and the choice to buy frozen over fresh matters more than organic vs. conventional or wild vs. farmed when considering global scale environmental impacts such as climate change, ozone depletion, loss of critical habitat, and ocean acidification.

he study is the world's first comprehensive global-scale look at a major food commodity from a full life cycle perspective, and the researchers examined everything -- how salmon are caught in the wild, what they're fed when farmed, how they're transported, how they're consumed, and how all of this contributes to both environmental degradation and socioeconomic benefits.

Article continues: http://www.sciencedaily.com/releases/2009/11/091124152803.htm