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12 December 2013 1:00 pm ,
Vol. 342 ,
The iconic 125-year-old Lick Observatory on Mount Hamilton near San Jose, California, is facing the threat of closure...
Recent results from the Curiosity Mars rover have helped scientists formulate a plan for the next phase of its mission...
A new, remarkably powerful drug that cripples the hepatitis C virus (HCV) came to market last week, but it sells for $...
In pretoothbrush populations, gumlines would often be marred by a thick, visible crust of calcium phosphate, food...
Evolutionary biologists have long studied how the Mexican tetra, a drab fish that lives in rivers and creeks but has...
Victorian astronomers spent countless hours laboriously charting the positions of stars in the sky. Such sky mapping,...
In an ambitious project to study 1000 years of sickness and health, researchers are excavating the graveyard of the now...
Stefan Behnisch has won awards for designing science labs and other buildings that are smart, sustainable, and...
- 12 December 2013 1:00 pm , Vol. 342 , #6164
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Ozone: Friend or Foe?
24 April 2008 (All day)
The ozone layer protects all life on Earth, but it's frustrating scientists' attempts to curb global warming. Take geoengineering: Researchers have proposed that injecting sulfur particles into the stratosphere might counter the effects of greenhouse gas buildup, but a new study suggests that the approach could thin the planet's already fragile ozone layer. Leaving the ozone layer alone comes with its own risks, however. A second study warns that the gradual recovery of the Antarctic ozone hole could speed the continent's warming.
The sulfur strategy goes like this: Researchers release sulfur particles from high-flying aircraft or large balloons in an attempt to mimic volcanoes. That's ostensibly a good thing, because the large amounts of ash and sulfur dioxide volcanoes eject reduce Earth's absorption of sunlight, resulting in a cooling effect. In 1991, for example, a large eruption by Mount Pinatubo in the Philippines flung out thousands of metric tons of SO2 and cooled temperatures, albeit slightly and temporarily, around the world.
But don't load those sulfur carriers just yet, says atmospheric scientist Simone Tilmes of the National Center for Atmospheric Research in Boulder, Colorado. Tilmes and colleagues analyzed the chemical actions of sulfur in the atmosphere, studied the effects of the Mount Pinatubo eruption, and modeled the potential impact of an attempted geoengineering effort. Adding sulfur to the atmosphere would spark chemical reactions leading to the liberation of chlorine, a compound known to destroy ozone, the team reports online today in Science. The effect, the researchers say, would reverse 2 decades of efforts to restore Earth's ailing ozone layer (ScienceNOW, 11 September 2007).
Physicist Paul A. Newman of NASA's Goddard Space Flight Center in Greenbelt, Maryland, says the paper is important because it identifies the relationship between atmospheric sulfur levels and "surprisingly large" ozone losses. "Nature provided us with an excellent 'geoengineering experiment' with the Mount Pinatubo eruption," he says. "We need to think long and hard before we experiment with the global climate," adds atmospheric scientist Uma Bhatt of the University of Alaska, Fairbanks. "We need more studies like [this] to assess the risk involved with geoengineering."
Meanwhile, a study conducted by researchers at the University of Colorado, Boulder, has concluded that a complete recovery by the Antarctic ozone hole--which developed in the 20th century because of the effects of ozone-destroying chemicals released into the atmosphere by human activity--could amplify warming in the Southern Hemisphere. Atmospheric scientist Judith Perlwitz and colleagues report in the 26 April issue of Geophysical Research Letters that if the ozone hole continues to recover, temperatures in the Antarctic stratosphere could rise as much as 9°C by the end of the century and contribute to global temperature increases.