Ozone layer most fragile on record

Roman Bystrianyk · medicine forum Guru Joined: 02 May 2005 Posts: 454

http://www.healthsentinel.com/news.php?event=news_print_list_item&id=776

Paul Brown, "Ozone layer most fragile on record", Guardian, April 27,
2005,
Link: http://www.guardian.co.uk/uk_news/story/0,3604,1470944,00.html

The protective ozone layer over the Arctic has thinned this winter to
the lowest levels since records began, alarming scientists who believed
it had begun to heal.

The increased loss of ozone allows more harmful ultraviolet light to
reach the earth's surface, making children and outdoor enthusiasts such
as skiers more vulnerable to skin cancer - a disease which is already
dramatically increasing.

Scientists yesterday reinforced the warning that people going out in
the sun this summer should protect themselves with creams and hats.

Research by Cambridge University shows that it is not increased
pollution but a side effect of climate change that is making ozone
depletion worse. At high altitudes, 50% of the protective layer had
been destroyed.

The research has dashed hopes that the ozone layer was on the mend.
Since the winter of 1999-2000, when depletion was almost as bad,
scientists had believed an improvement was under way as pollution was
reduced. But they now believe it could be another 50 years before the
problem is solved.

What appears to have caused the further loss of ozone is the increasing
number of stratospheric clouds in the winter, 15 miles above the earth.
These clouds, in the middle of the ozone layer, provide a platform
which makes it easier for rapid chemical reactions which destroy ozone
to take place. This year, for three months from the end of November,
there were more clouds for longer periods than ever previously
recorded.

Cambridge University scientists said yesterday that, in late March,
when ozone depletion was at its worst, Arctic air masses drifted over
the UK and the rest of Europe as far south as northern Italy, giving
significantly higher doses of ultraviolet radiation and sunburn risk.

The results, which were announced at a Geophysical Union meeting in
Vienna yesterday, are part of a European venture coordinated by
Cambridge University's chemistry department, which has been studying
the relationship between the ozone layer and climate change since May
2004.

Yesterday, Professor John Pyle, from the university, said: "These were
were the lowest levels of ozone recorded since measurements began 40
years ago. We thought things would start to get better because of the
phasing out of CFCs and other chemicals because of the Montreal
protocol, but this has not happened.

"The pollution levels have levelled off but changes in the atmosphere
have made it easier for the chemical reactions to take place that allow
pollutants to destroy ozone. With these changes likely to continue and
get worse as global warming increases, then ozone will be further
depleted even if the level of pollution is going down."

The relationship between the depletion of the ozone layer and climate
change is so complex that the EU is investing £11m in a five-year
project to try to understand and predict what is happening. Reporting
the results of the first year, the scientists told the meeting in
Vienna yesterday that "the atmospheric lifetime of these [ozone
depleting] compounds is extremely long and the concentrations will
remain at dangerously high levels for another half century."

Increased greenhouse gases in the air trap more heat in the lower
atmosphere, but the stratosphere far above the earth is getting colder.
As a result, ice clouds form between 14 and 26 kilometres above the
earth, exactly in the region where the protective ozone is found.

The European scientists reported the first signs of ozone loss in
January. As sunlight returned to northern latitudes, the rate of ozone
depletion increased and rapid destruction of ozone occurred throughout
February and March. In the altitude range where the ozone layer usually
reaches its maximum concentration, more than half of the ozone was
lost. In the lower atmosphere losses were not so great.

"Overall, about 30% of the ozone layer was destroyed," said Dr Markus
Rex, from the Alfred Wegener Institute in Potsdam, Germany, another
member of the team. He said the cold conditions which created polar
stratospheric clouds were four times more extensive in 2005 than in the
1960s and 70s.

Professor Pyle said overall the mixing of the air in the northern
hemisphere was far more rapid than in the Antarctic so a "hole" in the
ozone layer did not occur. Instead, as the air mixed in spring, there
was a general thinning of the protective ozone over the whole of the
northern hemisphere.

"It just means we have less natural protection than we should have and
we are used to. It means that we should be careful about exposing
ourselves to the sun, but that is already the case, this just makes
things slightly worse," he said.

The UV danger Ecology altered as Earth burns

· The thinning of the ozone layer allows more ultraviolet light - or
UV radiation - to reach the Earth's surface

· UV light stimulates the production of vitamin D in the skin, which
strengthens bones, but it also burns and causes skin cancer,
particularly in fair-skinned people. The UN environment programme
estimates that for every 1% thinning of the ozone layer there is a 2%
to 3% rise in skin cancer

· It also causes eye problems even if dark glasses are worn - mainly
cataracts and snow blindness -and can suppress the immune response to
the herpes virus and damage the spleen

· Excess UV radiation cuts photosynthesis in plants, reducing the size
and yield of winter wheat

· Plankton which are constantly exposed suffer damaged DNA. As some
species are more vulnerable than others, an increase in UV exposure has
the potential to cause a shift in species composition and reduce
diversity in ecosystems

· Reducing the world's populations of phytoplankton would
significantly impact the world's carbon cycle, because phytoplankton
store huge amounts of carbon in the ocean

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