Ozone loss over the Arctic this year was so severe that for the first time it could be called an “ozone hole” like the Antarctic one, according to scientists.
At about 20km (13 miles) above the ground, figures revealed 80% of the ozone was lost, and an Arctic ozone hole appeared over populated regions for parts of winter and spring for the first time ever since studies began.
Scientists believe the hole was a possible result of an unusually long period of cold weather at altitude. Cold weather optomizes the conditions that highten the activity of chlorine molecules that destroy ozone.
The much colder Antarctic now sees severe ozone depletion every winter. Ozone occurs in polar stratospheric clouds, with chlorine being the principal element in the breakdown of ozone concentrations. Chlorine based molecules last for decades in the upper atmosphere, and it may take until mid-century before the ozone layer is restored to natural pre-industrial levels of ozone.
The ozone layer blocks the deadly ultraviolet-B rays from the Sun which cause skin cancer. Stations in northern Europe and Russia registered increased levels of UVB penetration.
Dr Michelle Santee from NASA’s Jet Propulsion Laboratory (JPL): “Winter in the Arctic stratosphere is highly variable – some are warm, some are cold. It was continuously cold from December through April, and that has never happened before in the Arctic in the instrumental record.”
Although, the Arctic was ringing alarm bells this year, the Antarctic ozone hole remains comparatively stable from year to year with a large hole.