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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.
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.
Gretchen Cook-Anderson NASA Goddard Space Flight Center
June 29, 2006
SCIENTISTS FIND ANTARCTIC OZONE HOLE TO RECOVER LATER THAN EXPECTED
Scientists from NASA and other agencies have concluded that the ozone hole
over the Antarctic will recover around 2068, nearly 20 years later than
previously believed.
Researchers from NASA, the National Oceanic and Atmospheric Administration
(NOAA)
and the National Center for Atmospheric Research (NCAR) have developed a new
tool, a math-based computer model, to predict the timing of ozone hole recovery.
Their findings will be published tomorrow in Geophysical Research Letters.
The Antarctic ozone hole is a massive loss of ozone that occurs each spring
in the Southern Hemisphere. The ozone hole is caused by chlorine and bromine
gases in the stratosphere, an upper layer of the atmosphere, that destroy ozone
in an annually recurring process that takes place in the unique meteorological
conditions of the Antarctic stratosphere. Those gases come from human-produced
chemicals such as chlorofluorocarbons.
"The Antarctic ozone hole is the poster child of ozone loss in our
atmosphere," said lead author Paul Newman, a research scientist at NASA's
Goddard Space Flight Center, Greenbelt, Md. "Over areas that are
farther from the poles like Africa or the continental U.S., the annually
averaged levels of upper atmospheric ozone are only three to six percent below
natural levels. But, over Antarctica, ozone is 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."
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 anticipated 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.
International agreements such as the Montreal Protocol, approved in 1987,
limit production of ozone-depleting substances. Later changes to those
international agreements have completely eliminated legal production of most of
these chemicals, though there will be continued emissions of previously produced
and stored amounts of those chemicals that are not destroyed or recycled.
The researchers also show that the ozone hole has not yet started to
significantly shrink, something they predict will not start to occur until 2018.
Newman's team also further indicated that greenhouse gas-forced climate change
will have only a small impact on the Antarctic stratosphere and recovery of the
ozone hole.
The upper ozone layer is important because it blocks 90-99 percent of the
sun's ultraviolet radiation from making contact with Earth. This solar radiation
can cause skin cancer, genetic damage, eye damage and can impact marine life.
"My job is to track ozone-depleting chlorofluorocarbons around the globe
on a weekly basis," said Steven Montzka, a research chemist in the Global
Monitoring Division at NOAA's Earth Systems Research Laboratory in Boulder, and
co-author of the paper. "We make calculations with that information to
determine how gases containing chlorine and bromine that have life spans in the
atmosphere ranging from 45 to about 300 years, are affecting ozone. This new
prediction model is a very useful step forward to refining our understanding of
ozone hole recovery time scales."
The researchers included ozone data from the Total Ozone Mapping Spectrometer
(TOMS) on NASA's Earth Probe TOMS satellite, gas measurements from the Ozone
Monitoring Instrument (OMI) aboard NASA's Aura satellite, temperature
information from NOAA's polar orbiting series satellites, and data captured by
NOAA ground stations and weather balloons to create the new prediction model.
To view related Antarctic ozone hole images on the Web, visit:
http://www.nasa.gov/centers/goddard/news/topstory/2006/ozone_recovery.html
For more information about the Antarctic ozone hole on the Web, visit:
http://ozonewatch.gsfc.nasa.gov/
Contact:
Erica Hupp
NASA Headquarters, Washington
Phone: (202) 358-1237
Edward Campion
NASA Goddard Space Flight Center, Greenbelt, Md.
Phone: (301) 286-0697
This text derived from: http://www.nasa.gov/centers/goddard/news/topstory/2006/ozone_recovery.html
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