By Hemesh Patel
Daily Bruin Senior Staff
The United Nations announced last week in Geneva, Switzerland
that levels of ozone gas have increased over the Northern
Hemisphere.
The World Meteorological Organization, a UN agency, reported
that the concentration of ozone in the atmosphere is five percent
below normal.
“The ozone protects us from ultraviolet radiation that
gives us sunburns and put us at risk for skin cancer,” said
Roger Wakimoto, professor of atmospheric sciences.
The near-normal levels of ozone can be attributed to warmer than
average temperatures in the upper levels of the atmosphere.
But this comes as no surprise to UCLA scientists who say the
ozone layer is more likely to dissipate during the colder winter
and spring seasons.
“The increase in stratospheric ozone this year is probably
just a year-to-year variation and not an indication that the ozone
layer is currently regenerating,” said Jeffrey Lew, lecturer
for the Department of Atmospheric Sciences.
Chlorofluorocarbons, which were manufactured in the ’40s
and ’50s, found their way into aerosol sprays and
refrigerators.
“We created something that was a great refrigerant and it
won’t go away,” Wakimoto said.
While the chemicals functioned as propellant and as refrigerant,
they also contributed to the hole in the ozone layer.
The main problem with CFCs, however, is that these compounds
remain in the atmosphere for 100 years.
“The most severe depletion occurs at higher latitudes due
to ice particles,” said Richard Turco, director of
UCLA’s Institute of the Environment. “When the
stratosphere warms, there are fewer ice crystals and the ozone
layer is more slowly destroyed.”
Turco said the naturally occurring ice crystals that form clouds
in the stratosphere are made of nitric acid and water.
The presence of these clouds contribute to ozone depletion
because of a complex set of reactions that can only take place on
these ice crystals.
Once the CFCs interact with the ice crystals, they can release
Chlorine which reacts and finally destroys ozone.
But to limit the use of CFCs, scientists have developed
alternatives to these compounds, Hydrochlorofluorocarbons, that
have a shorter lifetime and do not contain destructive chlorine,
according to Turco.
These new alternatives to CFCs can help in the recovery of the
ozone layer in the long run.
Turco said, at this rate it will take tens of decades for the
ozone layer to be restored to normal levels.
While levels of ozone depletion over the Northern Hemisphere
seems to be improving, the same can not be said about the ozone
hole atop the Southern Hemisphere.
“The ozone hole is as deep as it has ever been,” Lew
said. “It’s usually just over the Antarctic but this
last season, the hole extended to Chile.”
HOW CFCs DESTROY THE OZONE LAYER Aerosols and
refrigerants release chlorofluorocarbons into the upper layers of
the atmosphere that eventually eat away at the ozone layer. The
ozone layer is found within the stratosphere and protects the Earth
from harmful UV rays, which are potentially cancerous to humans.
SOURCE: UCLA Department of Atmospheric Science Original graphic by
JOAN ONG/Daily Bruin Senior Staff Web adaptation by STEPHEN
WONG/Daily Bruin