Antarctica’s ozone issue
In 1985 3 scientists from the British Antarctic Survey raised the alarm regarding depletion of the ozone layer above Antarctica, the international community jumped into action at a speed rarely seen in the field of environmentalism. Only 2 years after the first report, the Montreal Protocol on Substances that Deplete the Ozone Layer came into action, banning the chlorofluorocarbons (CFCs) which, through human use, caused the damage.
Why does depletion take place over Antarctica?
Ozone depletion existing over Antarctica and not, for example, over Europe, is reflective of Antarctica’s uniquely harsh climate system. With each winter polar stratospheric clouds (PSCs) form through isolating vortex winds in the polar stratosphere. Chemical reactions within these clouds (forming in the austral winter) result in the releasing of harmful CFCs that in turn damage the ozone layer. With the return of spring in Antarctica, temperatures rise, this trend weakens, and the ozone layer (to a degree) recovers. Revelations from the scientific community in the 1980s, however, showed that ozone depletion wasn’t sufficiently recovering and that the ‘hole’ was growingly significantly due to CFC use
What about the Arctic?
Climate, once again, explains the disparity between ozone depletion in Antarctica and the Arctic. Ozone depletion, on a level as significant as in Antarctica, hasn’t occurred in the Arctic stratosphere. This is a result of the slightly warmer in the Arctic atmosphere conditions, which are less conducive to the formation of the PSCs that encourage the damage that the Antarctic ozone layer experiences. PSCs form at temperatures of -78 degrees Celsius and lower in the polar stratosphere: the Arctic only sees temperatures this cold for a couple of months a year, whilst Antarctica experiences them for 5-6 months a year. Some years, the Arctic doesn’t even reach the minimum temperatures needed for the formation to start with.
Why are changes to the ozone layer over Antarctica so alarming?
The state of the ozone layer matters for a number of reasons, but two are worth expanding in the context of global environmental change.
Firstly, if the ozone layer were to continue to degrade human animal, and plant DNA would be damaged by the harsh UVB rays that would normally be minimised significantly by the ozone layer. E
For this reason, the banning of CFCs in aerosols and the gradual repairing of the Antarctic ozone hole over the last 30 years is a monumental success – a testimony to international cooperation
Whilst the repairing of the ozone layer is, without doubt, positive, research over the past 15 years regarding the repairing ozone layer (and the subsequent potential for temperature increases) has far less rosy implications.
Here comes the second point raising concern…
Antarctica’s climate is integrally linked to the rest of Earth’s climate system. Changes in the fluxes, flows and trends of cooling and warming on the continent and in the Southern Ocean are significant globally, largely due to the threats of significant sea-level rise if mass and rapid melting were to take place. The warming temperatures being felt on the Antarctic Peninsula and West Antarctica are increasingly well documented: threats of rising temperatures on the continent, when combined with certain areas of new research regarding a repairing ozone hole and its link to the continent’s weather patterns, are alarming.
The key potentiality worrying some scientists is the potential for a reversal of the trend seen across the last 30 years which has seen the ozone hole creating negative radiative forcing and a ‘delayed breakup of the stratospheric polar vortex‘, keeping the continent isolated, harsh and cold.
The implications being made by a handful of scientific papers is that as the ozone layer repairs, positive radiative forcing could take place whereby the earth would be absorbing more energy from sunlight that it would be radiating outwards. Clearly, if this were to be the case, implications could be dire.
Important to note here is the uncertainty around these findings. Not only can we not concretely predict how large ice-sheets will react to changing wind patterns and so on, but the predictions regarding the impact of ozone repair itself are currently only early predictions. Some suggest that this impact could be weakened by the high albedo Antarctic snow has, especially in the areas where ozone depletion would impact.
There are also concerns around what a repairing ozone hole would mean for trends in the Southern Hemisphere Annular Mode (SAM). Recent trends imply that the ozone hole has encouraged a more positive SAM and thus stronger westerly winds. A repairing ozone hole could effectively see, therefore, the SAM more negative in the austral summer and thus warmer winds. However, the positive phase of SAM in non-summer months is thought to have the potential to remain strong due to rising greenhouse gas concentrations, so these two trends could have the potential to offset each other.
Reason to worry?
Acting with caution is surely the best way to progress when it comes to climate science in an environment as precarious as Antarctica. Here, however, it’s arguably a lose-lose situation. If we don’t continue the repairing of the ozone hole, our health, our literal DNA, could be irreversibly damaged in the future. If we do continue on the path we are headed (which is seeing the depletion over Antarctica repair), we could raise surface temperatures on a continent that holds over 60% of the world’s freshwater.
The potentialities are worrying, but not totally clear. What is clear, is that far more focus is needed on this area of climate science, to shed light on what the future really does hold for the Antarctic in the context of ozone depletion and recovery.