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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.
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.
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.
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Universe
Today -
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