New theory predicts the largest ozone hole over Antarctica will occur this month

2008-09-16 10:09:59

WATERLOO,
Ont. (Tuesday, Sept. 16, 2008) — A University of Waterloo scientist
says that cosmic rays are a key cause for expanding the hole in the
ozone layer over the South Pole — and predicts the largest ozone hole
will occur in one or two weeks.

Qing-Bin Lu,
a professor of physics and astronomy who studies ozone depletion, says
that it was generally accepted for more than two decades that the
Earth’s ozone layer is depleted by chlorine atoms produced by
sunlight-induced destruction of chlorofluorocarbons (CFCs) in the
atmosphere. But more and more evidence now points to a new theory that
the cosmic rays (energy particles that originate in space) play a major
role.

The ozone
layer is a layer in Earth’s atmosphere that contains high concentrations
of ozone. It absorbs almost all of the sun’s high-frequency ultraviolet
light, which is potentially damaging to life on Earth and causes
diseases such as skin cancer and cataracts. The Antarctic ozone hole can
be larger than the size of North America.

Lu says that
data from several sources, including NASA satellites, show a strong
correlation between cosmic ray intensity and ozone depletion. Lab
measurements demonstrate a mechanism by which cosmic rays cause drastic
reactions of ozone-depleting chlorine inside polar clouds.

Satellite
data in the period of 1980-2007, covering two full 11-year solar cycles,
demonstrate the significant correlation between cosmic rays and ozone
depletion.

“This
finding, combined with laboratory measurements, provides strong evidence
of the role of cosmic-ray driven reactions in causing the ozone hole and
resolves the mystery why a large discrepancy between the
sunlight-related photochemical model and the observed ozone depletion
exists,” Lu says.

For example,
the most recent scientific assessments of ozone depletion by the World
Meteorological Organization and the United Nations Environment
Programme, which use photochemical models, predict ozone will increase
by one to 2.5 per cent between 2000 and 2022 and Antarctic springtime
ozone is projected to increase by five to 10 per cent between 2000 and
2020.

In sharp
contrast, Lu says his study predicts the severest ozone loss —
resulting in the largest ozone hole — will occur over the South Pole
this month. The study also predicts another large hole will probably
occur around 2019.

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