Cold winter could lead to enlargement of ozone hole over North Europe

The record low temperatures recorded in the Arctic high atmosphere are causing increased destruction of the ozone layer across that region, leading to fears of an Antarctic style ozone hole over the northern hemisphere.

The ozone layer is located at an altitude of about 8km in the polar region and protects the earth from harmful solar UV radiation which can cause skin cancer.

Scientists from the EU SCOUT-03 Integrated Project have been studying changes in the thickness of the ozone layer in the Arctic on a daily basis since May 2004 with the aim of predicting future changes. They have found that extreme low temperatures speed up the destruction of the ozone layer as it is then that the CFC gases can operate most effectively. Since ozone destruction also requires sunlight, the ozone loss process starts after a cold winter when the sun returns to polar latitudes in spring.

"The Arctic has experienced an extremely harsh winter. The first signs of ozone loss have now been observed, and large ozone losses are expected to occur if the cold conditions persist," said European Commissioner for Science and Research Janez Potocnik.

Overall a decrease in total ozone in the Arctic region has been observed since 1980, although there is a considerable year-to-year variation in the observed values. This variability is to be contrasted with the Antarctic, where nearly complete ozone loss has occurred almost every winter since the late 1980s. The difference is linked to the Arctic warmer winter conditions.

The extreme conditions are of major concern and scientists will be addressing a number of questions, such as: How large will the ozone loss be? What will be the impact on UV radiation? Are the conditions for large ozone losses more favourable than before? "The meteorological conditions we are now witnessing resemble and even surpass the conditions of the 1999-2000 winter, when the worst ozone loss to date was observed," said Dr. Neil Harris of the European Ozone Research Co-ordinating Unit, Cambridge. "However, it is still too early to predict the temperature development in February and March, which are the crucial months for ozone loss in the Arctic. We will watch the development closely from day to day, and will inform the public and our authorities if the situation becomes worrying."

The cold conditions have worsened during the month of January, and in the last few days the geographical extent of polar stratospheric clouds has reached values much higher than ever observed in the Arctic.

By David Hopkins



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