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Headlines Published on 11 March 2005

Title Colder temperatures could widen ozone hole in northern hemisphere

The first signs of ozone depletion were observed over the Arctic this winter and continuing cold weather threatens to extend the potential losses, say scientists from the European SCOUT-03 project. A hole in the ozone could expose northern countries to increased ultraviolet radiation.

This animation is part of a skin cancer awareness campaign that has been running for almost 25 years in Australia © The Cancer Council Australia
This animation is part of a skin cancer awareness campaign that has been running for almost 25 years in Australia
© The Cancer Council Australia
Warnings about the dangers of overexposure to ultraviolet (UV) light – and the links to skin damage and cancer – have been par for course to residents of the southern hemisphere since news first broke about ozone losses in the 1980s. Now, with this winter's Arctic ozone layer being as cold as it is – and so closer to Antarctic temperatures – large ozone losses are also expected in the north.

Since last November, scientists from the EU-backed SCOUT-03 research project have noted the presence of large formations of clouds in the ozone layer – in the upper atmosphere – over the Arctic region. Continuing record low temperatures are making ozone depletion very likely later in the year when the sun returns to the poles and completes the cycle, the group predicted back in January.

The use of halogen-based substances, such as chlorofluorocarbons (CFCs) and halons, is generally blamed for increasing atmospheric concentration of chlorine and bromine, leading to ozone depletion. Rapid ozone loss can occur when temperatures drop below around -78°C some 20km above Earth’s surface – until this year, only occasionally reached in the Arctic ozone during winter.

The scientists are following the situation in the Arctic carefully using a combination of measurements and modelling. Data from the ground-based network of atmospheric observing stations and from satellites operating above the planet is combined in order to study the degree of ozone loss leading up to the warmer months in the northern hemisphere.

Slop on some sunscreen
“The meteorological conditions we are now witnessing resemble and even surpass [those] of the 1999-2000 winter, when the worst ozone loss to date was observed,” said Neil Harris of the European Ozone Research Coordinating Unit, Cambridge University (UK), and one of lead groups in SCOUT-03, which has 59 partner institutions with over 200 scientists working out of 19 countries.

Following the recent cold spell in February and March, the vortex of cold air over the Arctic has remained and the chances of ozone losses of 40% or more at the 18km region are high. With this loss, we can expect increases in ultraviolet radiation streaming down on northern parts of Europe, Harris warns. “Ozone absorbs UV rays from the sun and atmosphere, which means that if you have less ozone, the UV in the bottom range (8-12km) is increased,” he told Headlines. “Just how intense it is depends on localised issues at ground level, such as cloud cover, snow and how high up you are – skiers always have to be careful, for example.”

Similar developments in the southern hemisphere led to huge public awareness campaigns in Australia, South Africa and New Zealand, for example, where fair-skinned inhabitants, in particular, are encouraged to stay out of direct sunlight and to cover up as much as possible to prevent skin cancer and cell damage.

Harris says their team's instruments are planned to ride piggyback on the high-flying M55 Geophysika craft on flights run by two other EU projects, TROCCINOX and APE-INFRA, giving them a bird’s eye view of what is happening over the Arctic region. The situation will be discussed at SCOUT-O3’s annual meeting in Zurich (CH) this week.

Source:  Cambridge University, EU sources

Research Contacts page

More information:

  • Record low temperatures in Arctic ozone (Cambridge University, press release 28 January 2005)
  • The Cancer Council Australia (SunSmart campaign)

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