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The Question
(Submitted April 03, 1998)
What if our Ozone Layer had a very large hole in it, enough to cover
Australia?
The Answer
The ozone layer blocks out harmful ultraviolet (UV) rays from the Sun.
Where there is less ozone, more UV gets through. UV rays affect different
plants and animals in different ways--just as some people tan while others
burn, some species are more susceptible to damage from ultraviolet rays
than others.
An ozone 'hole', a place where there the ozone layer is thinner than
normal, was discovered a few years ago over Antarctica. Even at the ozone
levels found in the hole, most of the UV light is blocked before it reaches
the ground. But enough gets through to worry scientists.
The ozone hole is centered on Antarctica, so for it to stretch all the way
up to Australia, it would have to be quite large. That means that much of
the Antarctic Ocean and the Southern parts of other oceans would be exposed,
and these regions are very important to the world ecology. This might harm
some species of plankton and other ocean plants and animals. Nobody really
knows which species are most susceptible, and which will thrive as the UV
reduces the competition. The result might be worse (from our perspective)
than the current situation, because the current situation is what we are
used to--when something good changes, it usually becomes worse.
As for effects on individual people--an enlarged ozone hole would cause an
increase in tanning, burning, and skin cancer. However, the amount of UV
that gets through even 'normal' ozone layers is enough that it is wise to
wear a hat and sunscreen if you want to reduce your risk of skin cancer and
other effects.
More information is at
http://jwocky.gsfc.nasa.gov
including the press release at
http://pao.gsfc.nasa.gov/gsfc/service/gallery/fact_sheets/earthsci/ozonestu.htm
David Palmer
for Ask a High-Energy Astronomer
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