Multiple Factors Imperil Oceans

A new study published in Nature finds the oceans' capacity to store CO2 is diminishing, even as global emissions show no sign of significant reduction. This news has grave implications for the earth's atmosphere, which has been sharing an anthropogenic carbon burden with the oceans since the Industrial Revolution.

The study's research team, led by Dr. Saman Khatiwala of Columbia University's Lamont-Doherty Earth Observatory and the Georgia Institute of Technology, found the oceans' rate of uptake for CO2 began slowing in the 1980s and decreased by 10 percent between 2000 and 2007. As the water becomes more acidic, it loses its capacity to act as a carbon sink, shutting the door to emissions that are left to the atmosphere.

In addition to atmospheric effects, an article in the Boston Phoenix connects ocean acidification to a frightening and burgeoning loss of ocean life. Brian Skerry, an underwater photojournalist profiled for the article, describes changes he's seen in ocean life throughout his long career. Areas once thick with life are now dead zones, depleted by overfishing, bottom trawling, acidification and rising water temperatures.

Using the near extinct bluefin tuna as an example, Skerry says, "These are animals that cavemen painted on their walls, that Plato wrote about, wondering about their travels through the Earth's oceans. Yet we're wiping them out."

Daniel Pauly's September New Republic article, Aquacalypse Now, warns, "eating a tuna roll in a sushi restaurant should be considered no more environmentally benign than driving a Hummer or harpooning a manatee. In the past 50 years, we have reduced the populations of large commercial fish, such as bluefin tuna, cod and other favorites, by a staggering 90 percent."

Accelerated commercial fishing methods are one reason for the depletion of ocean life. New methods include GPS fish finders, radar, sonar technology and automated trawlers. An ocean that once teemed with life simply cannot compete with the appetites of the walking world.

In addition to overfishing, acidification caused by CO2 leads to a decrease in the carbonate ions crucial to the development of mollusks, shellfish and coral reefs. Warming adds another challenge to the mix -- the melting Greenland ice sheet adds a freshwater layer to the Atlantic, preventing the overturning of nutrients that spur the growth of plankton.

Although the news is sobering, Daniel Pauly ends his story on an empowering note. There's no need to end fishing, or to expect an end to fish. What we must do, says Pauly, is demand our political representatives put a stop to the "fishing industrial complex." The Nature study gives us another option. Regulating emissions and supporting climate change legislation is one more way to restore our oceans.