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Ozone recovery shows potential of regulation

Parry Singh Mudhar

December 21, 2014

Each year NASA and the National Oceanic and Atmospheric Administration (NOAA) conduct studies to determine the health of the ozone layer, particularly over the Antarctic. Fortunately, due to international regulations agreed to in the 1989 Montreal Protocol the thinning ozone layer around the lower polar region has gradually stabilized and recovery is hopeful.
The ozone layer of the atmosphere is 20 to 30 kilometers above ground. It is crucial for not only our health and food production, but also for the health and biodiversity of our oceans. The ozone layer actively blocks the Sun's ultraviolet light which can cause harmful damage to plant and animal life, notably skin cancer and cataracts in humans. Primary producers thriving in the photic zone of the ocean, where 90 per cent of marine life dwells, such as plankton are especially susceptible.
Although the Earth's natural changes such as the stratosphere's changing temperature has noticeable effects on the shrinking volume of ozone, independent scientific studies since the 1970's have shown that chlorofluorocarbons (CFCs) have an increasing effect on ozone loss.
Ozone-depleting substances
CFC's and other ozone-depleting substances (ODS) have been widely used since the 1930's in aerosol sprays and refrigerators. As these gases are released on the Earth's surface, they can circulate unchanged under the stratosphere for decades. Once these gases reach the mid to upper layer of the stratosphere, above the ozone layer, they react with the Sun's ultraviolet light to form chlorine, which reacts with and depletes ozone.
The Dobson Unit is most readily used when measuring and recording the concentration of ozone. 300 DU is the average ozone thickness in the stratosphere, which corresponds to around a 3 mm layer. 220 DU is considered a theoretical threshold in ozone thickness as practical observations since prior to 1979 had not shown ozone concentrations below this level.
The steady annual decrease in the south polar ozone layer began in the early 1980's with levels of 173 DU in 1982 dropping to 124 DU in 1985. Critically low concentrations were seen in 1991 as the level of ozone concentration fell below 100 DU and the lowest of 73 DU in 1994. Estimates put the amount of ozone depleting chlorine in the stratosphere, caused by human activity, to be as high as 80%. However, due to the Montreal Protocol the ozone layer has relatively stabilized since the mid-1990s.
Kofi Annan has stated that, "perhaps the single most successful international agreement to date has been the Montreal Protocol." Governmental cooperation laid out by the protocol phased out and then eliminated key ODS. The concentration levels of the most damaging ODS, including CFCs, have decreased or at least leveled off since the mid-1990's.
Although current models show that recovery of the south polar ozone will occur around 2040, it will take until 2050 to 2070 to return to 1980 levels. However, the ozone layer covering various other topological areas are still at risk, the mid-southern and tropic regions will need much more work and most importantly time to repair due to human accelerated factors such green house warming.
Like the climate change deniers of today, various ODS manufacturing industries were quick to deny the impacts of their products regardless of the amount of credible and peer reviewed scientific data being published on the matter. One member of DuPont's board claimed that scientific work into CFC's effect on the depletion of the ozone was, "a science fiction tale...a load of rubbish...utter nonsense." Industry has learned from this defeat and no international treaty regulating green house gases has been signed.
Even now the Canadian Conservative government is taking a similar stance to Dupont with its silencing of scientists and disregard to published and peer reviewed scientific and economic data showing the climate effects of the tar sands and risk of oil spills along any one of the many proposed routes.
The data is present, and it's up to all of us to build an anti-capitalist climate movement that can bring about the changes that we need.

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