The Ozone Hole over the Antarctic in 2013 was slightly smaller than the average sized hole in recent decades. This has led some scientists to believe we are beginning to see proof that the world’s ozone depletion has leveled off with the first signs of improvement.
Most of the world’s scientists are more cautious however, pegging the first date for when we will see tangible evidence of healing at a decade from now. At that projected rate, full recovery will not occur until 2070.
In the short term there are annual fluctuations in the size of the hole that have puzzled scientists. For instance while the size of the 2011 ozone hole was almost as big as that in 2006, which was the largest hole on record, the size of the ozone hole in 2012 was the second smallest on record.
Recent studies indicate that weather patterns play a more important role in the size of the hole in any given year than previously thought. Dr. Susan Strahan of Nasa’s Goddard Space Center in Maryland said, “We have identified another factor that wasn’t fully recognized before: and that is how much ozone gets brought to the polar regions in the first place, by the winds.”
This revelation has forced scientists to come up with an alternate explanation of the annual size of the ozone hole. Their analysis is that it depends on the various layers of the stratosphere that are involved and the wind’s influence. Scientists believe that the more ozone is blown into the lower stratosphere there is a greater supply to destroy and the hole looks bigger. They believe this is what happened in 2006.
In 2011 the winds blew less ozone into the lower stratosphere so the ozone there was destroyed more quickly making the hole look bigger. The scientists theorize that in 2012 the ozone was pushed into the upper stratosphere that masks the hole below and makes it look smaller.
This is not our first miscalculation. When we originally attacked our ozone problem, we were not as sensitive to climate change as we are now. Instead we were intent on the signing of the 1987 Montreal Protocol addressing ozone depletion. In order to protect the ozone, parties to the Montreal Protocol approved the use of hydrofluorocarbons (HFCs) to replace the more ozone damaging chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and halons. Also, selected third world countries were left out of the agreement. (See January 2013 posting, “Are We Trading Greenhouse Gas for Ozone”).
Unfortunately we have come to regret our endorsement of HFCs as an ecofriendly substitute for CFCs, HCFCs, and halon gas. While HFCs do not contain chlorine or bromine and therefore do not interact with ozone, they are powerful greenhouse gases that over time could negatively contribute to climate change. Two varieties of HFC are particularly troubling because of how long they last in the atmosphere. HFC-134 has an atmospheric lifetime of about 14 years while HFC-23 has a lifetime of 260 years.
In 2013 President Barack Obama announced an agreement in principle with India and signed a formal agreement with China to work at eliminating completely the use of the banned chemicals CFCs, HCFCs and halon gas. In addition, the June 8, 2013 signed agreement with President Xi of China specifically mentions the threat of HFCs and indicates a willingness to significantly reduce the use of these chemicals as well.
Although this U.S./China document and the accompanying agreement by the G-20 countries on HFCs do not specify concrete steps or binding deadlines they do represent positive developments in the formal recognition of the problem. The positive sentiments to make progress are encouraging to those of us that continue to be concerned about ozone depletion and global climate change.
Also encouraging are developments by the world’s major chemical producers who have developed alternative chemicals to replace HFCs. DuPont has specifically mentioned their new family of refrigerants, Opteons, as a suitable replacement for other, more harmful, refrigerants.
Use the following links to obtain more information or see the original source documents: