NASA Study Finds Clock Ticking Slower On Ozone Hole
Recovery
The Antarctic ozone hole's recovery is running late. According to a
new NASA study, the full return of the protective ozone over the
South Pole will take nearly 20 years longer than scientists
previously expected.
This
still image is from an animation that zooms down to Antarctica and
shows the daily ozone readings from July 1, 2005 to October
25,2005.
Scientists from NASA, the National Oceanic and Atmospheric
Administration and the National Center for Atmospheric Research in
Boulder, Colo., have developed a new tool, a math-based computer
model, to better predict when the ozone hole will recover.
The Antarctic ozone hole is a massive loss of ozone high in the
atmosphere (the stratosphere) that occurs each spring in the
Southern Hemisphere. The ozone hole is caused by chlorine and
bromine gases in the stratosphere that destroy ozone. These gases
come from human-produced chemicals such as chlorofluorocarbons,
otherwise called CFCs.
The ozone layer blocks 90-99 percent of the sun's ultraviolet
radiation from making contact with Earth. That harmful radiation
can cause skin cancer, genetic damage, and eye damage, and harm
marine life.
This
image shows the ozone hole on September 11, 2005. The ozone
thinning over Antarctica reached its maximum extent for the year on
this date.
For the first time, a model combines estimates of future Antarctic
chlorine and bromine levels based on current amounts as captured
from NASA satellite observations, NOAA ground-level observations,
NCAR airplane-based observations, with likely future emissions, the
time it takes for the transport of those emissions into the
Antarctic stratosphere, and assessments of future weather patterns
over Antarctica.
The model accurately reproduces the ozone hole area in the
Antarctic stratosphere over the past 27 years. Using the model, the
researchers predict that the ozone hole will recover in 2068, not
in 2050 as currently believed.
"The Antarctic ozone hole is the poster child of ozone loss in our
atmosphere," said author Paul Newman, a research scientist at
NASA's Goddard Space Flight Center, Greenbelt, Md. And lead author
of the study. "Over areas that are farther from the poles like
Africa or the U.S., the levels of ozone are only three to six
percent below natural levels. Over Antarctica, ozone levels are 70
percent lower in the spring. This new method allows us to more
accurately estimate ozone-depleting gases over Antarctica, and how
they will decrease over time, reducing the ozone hole area."
International agreements like the Montreal Protocol have banned the
production of most chemicals that destroy ozone. But the
researchers show that the ozone hole has not started to shrink a
lot as a result. The scientists predict the ozone hole will not
start shrinking a lot until 2018. By that year, the ozone hole's
recovery will make better time.
