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Volcanic
aerosol clouds and gases lead to ozone destruction
8 Nov 2006-Volcanic eruptions
destroy ozone and create ‘mini-ozone holes’, according to two new studies by
researchers at the Universities of Cambridge and Oxford.
The new research, spearheaded by
Dr Genevieve Millard at the Department of Earth Sciences, University of
Cambridge, discovered that volcanic gases released during eruptions accelerate
reactions that lead to ozone destruction. The researchers found that even
relatively small volcanic eruptions can destroy ozone and create localised ‘holes’
in the stratosphere.
Previously, scientists had
concentrated on the climatic effects of the tiny particles of volcanic sulphate
created from the sulphur dioxide gas emitted during an eruption. For the first
time, analysing data from a 2000 eruption of the Hekla volcano, Iceland, the
researchers discovered that volcanic gases may also lead to the formation of ice
and nitric acid particles. This is a critical finding as these particles ‘switch
on’ volcanic chlorine gases, accelerating reactions that lead to ozone
destruction.
Dr Millard said, “We have shown
for the first time that volcanic eruptions which penetrate the stratosphere can
lead to the formation of the type of clouds that promote reactions with volcanic
chlorine gases - gases that destroy stratospheric ozone and lead to the
formation of ‘mini-ozone holes’.”
The ozone losses due to the small
eruption at Hekla lasted for about two weeks, and eventually returned to normal
levels. This is the first time that people have observed the complete removal of
local ozone following a volcanic eruption.
“Now we want to find out what
might happen to the ozone layer after a much larger eruption,” said Dr David
Pyle, University of Oxford, project coordinator. “For example, is there
significant loss of ozone and increased ultra-violet radiation at low latitudes
following large explosive eruptions? We want to understand this, so that we can
have a better picture both of what might have happened in the past, and of what
may happen in the future.”
For further information, please
contact the University of Cambridge Office of Communications on 01223 332300
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