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The Return of the Ozone Layer |
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By Julio Godoy*
The
Montreal Protocol on ozone-depleting substances is making verifiable
progress. Future generations may be able to enjoy fun in the sun
with fewer threats to their health, predict some experts.
PARIS - The ozone layer of the Earth's atmosphere,
assailed for decades by chemical products used in industry and agriculture,
could begin to regenerate itself in the years ahead, predicts Rajendra
Shende, director of the United Nations Environment Program's Energy
and Ozone Action Unit.
In a conversation with Tierramérica, Shende said observations by
scientists from the World Meteorological Organization (WMO) and
NASA, the U.S. space agency, indicate that the ozone hole -- an
area of thinning in the atmosphere -- has achieved its maximum size
and will begin to shrink in the decades to come.
For more than 30 years, meteorologists from these and other organizations
have been observing and quantifying the concentration of ozone-depleting
substances in the atmosphere.
''Today it is possible to establish that the rate of increase of
the concentration of those chemicals has begun to diminish,'' thanks
to the implementation of the Montreal Protocol, signed in 1989,
said Shende.
WMO records from early September suggest that the loss of ozone
above the Earth's poles has been on the decline for five years.
The famous ozone hole, the area of thinning over Antarctica, measured
around 12.5 million square km on Sep. 1, half the size estimated
in September 2000. This annual phenomenon reaches its peak in September
or October.
However, that variance is due in part to climatic factors. ''In
colder years, the same amount of ozone-depleting compounds can destroy
more ozone in comparison to warmer years,'' explained Daniel Albritton,
director of the aeronomy laboratory of the U.S. National Oceanic
and Atmospheric Administration (NOAA).
Shende stressed that the regeneration of the ozone layer would take
at least 50 to 60 years.
''If we continue to eliminate emissions (of ozone-depleting chemicals),
our great-grandchildren might be able to sunbathe on the beaches
of Argentina, Norway and Australia without the fears that our children
face today,'' he said.
Maintaining the current trend towards regeneration depends on the
continued application of the Montreal Protocol, and the absence
of natural phenomena that also deplete the ozone layer, such as
major volcanic eruptions, added the expert.
Ozone, a very unstable molecule made up of three oxygen atoms, constitutes
a layer in the atmosphere -- at 15 to 50 km above the Earth's surface
-- that filters out much of the Sun's ultraviolet rays. Excessive
exposure to UV radiation causes skin cancer, eye cataracts and even
blindness, as well as the destruction of plant life.
Some 90 chemical products used in farming and industry, particularly
for refrigeration, air conditioning and fire-fighting equipment,
destroy ozone molecules when they reach the stratosphere, especially
near the Earth's poles.
Among these substances are CFCs (chlorofluorocarbons), halons, carbon
tetrachloride, hydrobromofluorocarbons, methyl bromide and bromochloromethane.
When they arrive in the upper reaches of the atmosphere, catalytic
chemical reactions occur that break down ozone.
Scientists first identified these reactions 40 years ago over Antarctica,
and they also occur over the North Pole.
In 1989, after long and difficult negotiations, representatives
from 29 countries plus the European Economic Community signed the
Montreal Protocol, in the Canadian city of that name.
The signatories represented 82 percent of total global consumption
of ozone-depleting chemicals.
To date, 184 countries have ratified the Protocol, which seeks the
elimination of substances that destroy the ozone layer as its final
objective, but is based upon a flexible methodology.
For example, the Protocol has led to the halt of production and
use of CFCs in refrigerators and air conditioners in industrialized
countries, but these substances continue to be used for those purposes
in the developing world.
The treaty sets the goal of complete elimination of the pesticide
methyl bromide in the industrialized world by January 2005, but
extends the deadline to 2007 for developing countries to phase out
production and use of this chemical.
If an industrialized country that has signed the Protocol proves
that it faces insurmountable difficulties in eliminating the pesticide
before January, the treaty allows for an extension of up to one
year, with a ''transitive'' clause, meaning that if one country
is granted a later deadline, other nations will benefit from the
same.
In July, the United States requested that such extensions be granted
for several years. The proposal will be up for debate during the
16th Meeting of Parties to the Montreal Protocol, to take place
in Prague, Nov. 17-26.
* Julio Godoy is an IPS correspondent.
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