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 | 