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ENVIRONMENT: The Return of the Ozone Layer
By Julio Godoy*
PARIS, Sep 14 (Tierramérica) - 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 Programme's Energy and Ozone
Action Unit.
In a conversation with Tierramérica, Shende said observations by scientists
from the World Meteorological Organisation (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 organisations
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 on Ozone-Depleting Substances,
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 have also been found to occur over the North Pole.
In 1989, after long and difficult negotiations, representatives from 29
countries plus the European Economic Community signed the Protocol, in the
Canadian city of Montreal.
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 industrialised 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 industrialised world by January 2005, but extends the
deadline to 2007 for developing countries to phase out production and use of
this chemical.
If an industrialised 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. Originally published Sep. 11 by
Latin American newspapers that are part of the Tierramérica network.
Tierramérica is a specialised news service produced by IPS with the backing
of the United Nations Development Programme and the United Nations
Environment Programme.)
(END/2004)
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