Oceans Absorb Less Carbon Dioxide as Marine Systems Change (Study)

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. "Our method takes as input the relatively well-known atmospheric CO₂ concentration history. Given this history, we calculate the ocean absorption of industrial CO₂ consistent with this history," Khatiwala said.

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.

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Photo courtesy NOAA

U.S. Navy to Make Jet Fuel From Seawater

The U.S. Navy could be on to something big in its latest research project -- making jet fuel from seawater. Chemists at the Naval Research Laboratory hope to secure a cheap and steady fuel source for its fleet of jets by extracting dissolved carbon dioxide from seawater and combining it with hydrogen stripped from water molecules. Converting the CO2 and hydrogen into jet fuel could be done through a process known as Fischer-Tropsch, which typically starts with carbon monoxide and hydrogen and, using metal catalysts and heat, ends with a mixture of methane, waxes and synthesis gas (syngas), which can then produce fuel or plastic.

Fischer-Tropsch is expensive and energy-intensive, which often limits its usefulness. One of the few times it has proven economical was using solid coal to produce liquid fuel for World War II Germany.

Instead of coal, the chemists want to use the carbon dioxide dissolved in seawater (140 times the amount found in the atmosphere) and hydrogen stripped from water as the base materials for the reaction.

They also want to change the metal catalysts, switching from cobalt, which produces mostly methane, to iron, which drops methane production by 70 percent and increases the amount of syngas produced. Source: Discovery Channel

Photo credit: Discovery Channel

EPA to Declare Carbon Dioxide a Dangerous Pollutant

Carbon dioxide will be declared a dangerous pollutant shortly. This move could help jump-start the slow-moving climate-change legislation on Capitol Hill. EPA administrator Lisa Jackson said a formal "endangerment finding," which would trigger federal regulations on greenhouse gas emissions, probably would "happen in the next months."

Jackson disclosed her timeline even as top senators said they were delaying plans to introduce legislation that would set new limits on carbon dioxide emissions. They were set to unveil legislation next Tuesday, but the date has now been pushed back to a later date in September.

The EPA kick-started the regulatory process in April when it proposed declaring carbon dioxide and five other greenhouse gases as pollutants that jeopardize the public health and welfare. EPA scientists believe the greenhouse gases contribute to global warming by trapping heat in the Earth's atmosphere. The EPA can formalize the finding anytime, now that it has closed a 60-day public comment period that netted more than 300,000 responses.

A formal endangerment finding would obligate the agency to regulate greenhouse gas pollution under the Clean Air Act - even if Congress doesn't pass a final climate-change bill. Source: San Francisco Chronicle

This is a move that will be applauded by many environmentalists. President Barack Obama and Lisa Jackson said they prefer that Congress, instead of the EPA, lead the charge in implementing new greenhouse gas limits.