Ozone levels over the Arctic have been plummeting in recent days, and look to be heading for a record loss.
Testing at a network of over 30 ozone sounding stations across the Arctic and Subarctic has shown that at the relevant altitudes about half of the ozone that was present above the Arctic has been destroyed over the past few weeks.
"Since the conditions leading to this unusually rapid ozone depletion continue to prevail, we expect further depletion to occur," says Markus Rex of the Alfred Wegener Institute for Polar and Marine Research.
And the changes may have an impact beyond the Arctic. Air masses exposed to ozone loss above the Arctic tend to drift southwards later, so that episodes of high UV intensity could also occur in middle latitudes.
"Special attention should thus be devoted to sufficient UV protection in spring this year," says Rex.
The breakdown products of chlorofluorocarbons (CFCs) destroy ozone when exposed to extremely cold conditions. And with climate change apparently making Arctic winters colder, there have been greater ozone losses.
CFCs released in the past won't vanish from the atmosphere for decades yet. In the long term, though, the ozone layer will recover, thanks to extensive environmental policy measures enacted for its protection.
"By virtue of the long-term effect of the Montreal Protocol, significant ozone destruction will no longer occur during the second half of this century," says Rex.