viernes, 12 de junio de 2009
Ozone Hole Worsens Climate Predictions
This image shows the 2008 ozone hole maximum, reached on Sept. 12. The ozone hole is shifting air currents, which are preventing waters from soaking up the man-made greenhouse gas carbon dioxide (CO2), and simultaneously worsening the effects of ocean acidification.he depleted ozone layer is wreaking havoc with winds over Antarctica and the Southern Ocean, according to a new study.
Shifting air currents are preventing waters from soaking up the man-made greenhouse gas carbon dioxide (CO2), and simultaneously worsening the effects of ocean acidification.
Led by Andrew Lenton of the Pierre and Marie Curie University in France, a team of researchers found that between 1987 and 2004, stronger winds over the Southern Ocean dredged up deep, carbon-rich waters. With carbon concentrated near the surface, a total of nearly 2.5 billion tons of atmospheric CO2 couldn't dissolve into the ocean.
By comparison, human activity emits around 8 billion tons of carbon each year.
Carbon in the upper reaches of the ocean makes the waters more acidic. While scientists still don't fully understand how acidification affects marine life, they worry that plunging pH could damage populations of plankton, krill, and fish larvae -- organisms that form the foundation of the food web."The ocean is a really massive store of natural carbon," Corinne Le Quere of the University of East Anglia in the United Kingdom, who was not involved in the study said. "Changes in circulation patterns can cause outgassing of that carbon."
The team thinks the hole in the ozone layer is to blame for the mess. Ozone is a greenhouse gas that acts as a heat blanket, preventing the upper atmosphere from getting too cold.
With the layer stripped away, the stratosphere has gotten colder. Because heat escapes more readily into a cold atmosphere than a warm one, the flow of ocean and air currents is fueled by the flow of heat escaping into the atmosphere and, ultimately, into outer space.
So the colder stratosphere changes wind patterns all the way down to the Southern Ocean's surface.
"Our results suggest that predictions of future climate that do not account for stratospheric ozone depletion likely overestimate regional and global oceanic CO2 uptake and underestimate ocean acidification," the team wrote in a paper due to be published in the journal Geophysical Research Letters.
Le Quere added that similar carbon-rich upwelling is starting to show up in the north Atlantic and west Pacific Oceans. If true, it could enhance acidification in those regions as well, with potentially adverse affects on huge swaths of marine life.