Cooler temperatures in the ozone layer above the Arctic have recently caused a dramatic drop in ozone levels, suggesting that the region is in for a record loss of the trace gas that protects the planet’s surface from ultraviolet radiation from the sun.
“Our measurements show that at the relevant altitudes about half of the ozone that was present above the Arctic has been destroyed over the past weeks,” says Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association (AWI) researcher Markus Rex. “Since the conditions leading to this unusually rapid ozone depletion continue to prevail, we expect further depletion to occur.”
The research has been coordinated by the Potsdam Research unit of the AWI which has overseen measurements taken by over 30 ozone sounding stations spread across the Arctic and Subarctic regions.
These changes in the ozone layer are likely to have an effect on regions south of the Arctic as well. Air masses above the Arctic which are exposed to ozone loss tend to drift southwards, increasing the UV intensity in middle latitudes.
“Special attention should thus be devoted to sufficient UV protection in spring this year,” recommends Rex.
Ozone Depletion 101
The ozone layer exists in the upper atmosphere and prevents the Sun’s damaging electromagnetic radiation reaching the planet’s surface. However, anthropogenic chlorofluorocarbons (CFCs) throughout the years prior to the Montreal Protocol being enacted in 1987 have had a substantially damaging effect on the ozone layer, reducing the strength of the ozone layer by up to 70% in the early 80’s over Antarctica, and increasing the UV intensity over locations such as Tasmania, Australia, dramatically.
The Montreal Protocol is an international treaty adopted under the United Nations umbrella which essentially bans the production of CFCs worldwide.
However, the CFCs already in the atmosphere will reside there for another few decades, and are still having a deleterious effect on the ozone layer, specifically when combined with extremely cold temperatures.
Additionally, though paradoxically, scientists have pointed to a link between ozone loss and climate change, particularly the fact that the coldest winters in the Arctic stratosphere where the ozone is have been getting stronger and leading to larger ozone losses.
“The current winter is a continuation of this development, which may indeed be connected to global warming,” Rex explains. “To put it in a simplified manner, increasing greenhouse gas concentrations retain the Earth’s thermal radiation at lower layers of the atmosphere, thus heating up these layers. Less of the heat radiation reaches the stratosphere, intensifying the cooling effect there.”
In short, the anthropogenic greenhouse gasses keeping the warmth closer to the surface of the planet are ensuring that the colder parts of our atmosphere get colder. The problem is that it is in those parts of the atmosphere where the ozone is, and as a result, combined with CFCs, is seeing increased ozone loss.
The Good News
As a result of the Montreal Protocol, CFCs will start to degrade and disappear before the middle of this century, reducing the chance of ozone loss. “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,” explains Rex.
Source: Alfred Wegener Institute