The ozone layer, the thin seam of gas surrounding the planet, acts as a screen against harmful ultraviolet rays reaching the earth's surface. UV-B rays have been linked to skin cancer, cataracts and damage to the human immune system. Some crops and forms of marine life can also suffer adverse effects. Scientists have long known about how chemicals can eat away at the ozone layer, but what about other factors, like climate change? A mission has been researching the issue in the Arctic to find out how temperature shifts have an effect on the ozone layer, and it has already brought back some revealing results.
The project, RECONCILE, is studying the chemistry of ozone depletion in the stratosphere based on model and lab studies as well as field campaigns which included high altitude flights over the Arctic. Backed by a €3.5 million European Union (EU) grant, the four-year project started in March 2009 with 18 partners from eight countries.
The researchers gathered material for their climate chemistry models by sending a special aircraft into the cold Arctic stratosphere where temperatures are as low as minus 80°C. The GEOPHYSICA is a Russian plane that was constructed to host a large number of instruments for chemical and physical measurements and that is able to fly at altitudes up to 21 km. It has already served as a platform for stratospheric research in a number of former EU projects.
While researchers are already familiar with the processes that deplete ozone in the stratosphere, the project looked at how effective these processes really are, and how they relate to climate change. "We felt that we did not know everything about Arctic ozone depletion that we should know," says project coordinator Marc von Hobe, from German research centre Forschungszentrum Jülich. "By the end of the RECONCILE project, we will be able to say that we fully understand the processes actually destroying ozone in the polar regions."
The link between ozone loss and climate change is particularly striking in the Arctic, where the coldest winters are getting colder, thus leading to larger ozone losses. Greenhouse gases accumulating in the atmosphere hold the Earth's thermal radiation at lower atmospheric levels and cool the higher levels which are under certain circumstances intensifying the chemical cycles that destroy ozone.
Thanks to the 1987 Montreal Protocol, the treaty banning the use of harmful chlorofluorocarbons (CFCs), the ozone layer has stabilised. However, CFCs released over prior decades are likely to remain in the atmosphere for many decades to come.
RECONCILE which won the FRP NRW Award in April 2011 for the most innovative and efficient coordination concept of EU projects in North Rhine-Westphalia has already found that the low temperatures in the Arctic can trigger large-scale ozone depletion. In turn, the loss of ozone means the Arctic has lost part of its shield against ultraviolet rays.
"We essentially confirmed the current theory of how an ozone hole is formed," says von Hobe, pointing to the record ozone loss over the Arctic in 2011. "We also managed to improve models so we can make more accurate predictions about the future of the ozone layer in times when climate change may alter the dynamics and composition of the atmosphere."
Von Hobe says he hopes the research can eventually help preserve the environment for future generations. "The more we understand about climate, the ozone layer, and our atmosphere in general, the better we can foresee the consequences of our actions such as emitting greenhouse gases, or CFCs," he says. "In projects such as RECONCILE, we as scientists try to perfect our understanding and develop models of 'possible futures'. Taking the necessary policy action to avoid some of the more unpleasant ones is then up to the politicians."