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September
13, 2007
NASA KEEPS EYE ON OZONE LAYER
AMID MONTREAL PROTOCOL'S SUCCESS
NASA scientists will join researchers from
around the world to
celebrate the 20th anniversary of the Montreal Protocol, an
international
treaty designed to reduce the hole in Earth's protective ozone layer.
The
United Nations Environment Programme will host the meeting from Sept.
23 to 26
in Athens,
Greece.
NASA scientists study
climate change and research the timing of the recovery of the ozone
layer.
"The Montreal Protocol has been a resounding success," said Richard
Stolarski, a speaker at the symposium from NASA's Goddard
Space Flight
Center, Greenbelt,
Md.
"The effect can be seen in the leveling off of chlorine compounds in
the
atmosphere and the beginning of their decline."
Since the Montreal Protocol was signed on Sept. 16, 1987, more than 100
nations
have agreed to limit the production and release of compounds, notably
human-produced chlorofluorocarbons, known as CFCs. CFCs and a list of
other
compounds are known to degrade the layer of ozone in the stratosphere
that
shields life from the sun's ultraviolet radiation. That process gives
rise to
the ozone hole above Antarctica.
Today, space-based instruments aboard NASA's Aura satellite monitor the
chemical make-up of the atmosphere and collect data that will help
researchers
better understand ozone chemistry through computer models. While the
data show
that average chlorine levels are beginning to decline, springtime ozone
depletion in the polar regions continues to be a prominent atmospheric
feature.
"The goal now is to ensure that CFCs and other emissions continue to
fall
to below the levels that produce an ozone hole," said Goddard's Anne
Douglass, the deputy project scientist for Aura. "This won't happen
until
about 2070."
NASA and National Oceanic and Atmospheric Administration scientists
announced
in 2006 that the hole was the largest ever observed, at 10.6 million
square
miles. The size of the hole will approach its annual peak in late
September.
Scientists at the symposium will discuss 20 years of scientific
progress, as
well as how best to monitor the atmosphere to ensure the goals of the
treaty
are realized.
In addition to the current satellite measurements, NASA research
efforts use
data collected on the ground, in the air and from previous missions.
Data from past satellite observations have been essential to
understanding
ozone depletion. NASA's Total Ozone Mapping Spectrometer, or TOMS, was
one of
NASA's signature ozone research achievements. TOMS launched in 1978 and
was
decommissioned in May 2007.
"The TOMS images of the Antarctic ozone hole caused worldwide alarm and
thus played a key role in the Montreal Protocol and other international
agreements to phase out the offending chemicals from our environment,"
said Goddard's Pawan Bhartia, project scientist for the mission. In
addition,
measurements from the Stratospheric Aerosol and Gas Experiment, along
with the
Microwave Limb Sounder and the Halogen Occultation Experiment aboard
the Upper
Atmospheric Research Satellite, were important to scientists'
understanding of
ozone.
Scientists collect atmospheric composition data from ground-based
monitoring
stations around the world. Researchers have collected measurements
since 1978
for nearly all compounds identified in the Montreal Protocol. The data
come
from coastal monitoring stations used in previous missions and as part
of the
NASA-sponsored Advanced Global Atmospheric Gases Experiment.
Airborne instruments have been a critical piece of the scientific
search to
find the cause of ozone depletion, and they remain central to NASA's
research
efforts today.
Data from NASA's Airborne Antarctic Ozone Experiment in 1987 "provided
the
smoking gun measurements that nailed down the cause of the ozone hole
being the
increase of CFCs combined with the unique meteorology of the
Antarctic,"
Stolarski said. Since then, NASA has sponsored several airborne field
campaigns
that have furthered understanding of the chemical processes controlling
ozone.
These measurements are key for researchers working to predict the
future of the
global ozone layer. The differences between loss and recovery of ozone
at the
poles and in non-polar regions are complex. "Such complexity has led to
heated debates over the timing and extent of recovery," said Ross
Salawitch, an atmospheric chemist at the Jet Propulsion Laboratory, Pasadena,
Calif.
The modern focus in ozone research also has shifted to include the
effects of
climate change. "Twenty years ago we went out of our way to separate
ozone
depletion from climate change," Salawitch said. "After a decade of
looking at data, the community realizes they are linked in subtle but
profoundly important ways."
For more information, visit:
http://www.nasa.gov/vision/earth/environment/ozone_resource_page.html
##
Contact:
Tabatha
Thompson
NASA Headquarters
202-358-3895
tabatha.thompson-1@nasa.gov
This text is derived from:
http://www.nasa.gov/home/hqnews/2007/sep/HQ_07192_montreal_protocol.html
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