Good news for the planet, and by extension for all life on it, even though it has been thirty years in the making: the ozone hole is closing. A group of researchers from MIT and the University of Leeds has published a study with the clearest evidence to date that the ozone layer is recovering. The researchers place the main reason on the entry into force of the Montreal Protocol, which established the ban on chlorofluorocarbons.
The Montreal Protocol: A Landmark Treaty
Agreed on September 16, 1987, with effective entry into force on January 1, 1989, the Montreal Protocol went through eight revisions between 1990 and 2007, making it the most successful international treaty. Experts will surely highlight that the protocol is actually the mechanism that emerged from the Vienna Convention for the Protection of the Ozone Layer, presented on May 22, 1985. The point is that the fight against the ozone hole and the global deterioration of the layer has been going on for more than thirty years, and although far from over, a group of researchers from MIT and the University of Leeds reported what we wanted to hear: It is working.
Volcanic Influence and the Study
The ozone hole has changed its size over the past few years, in some cases drastically. In October 2015, the hole reached 23 million square kilometers, 20 percent "bigger" than the previous year, but the main reason was an increase in volcanic activity, and researchers point to the three eruptions that Calbuco volcano had in April of that year, after remaining dormant for more than four decades. That led them to use the month of September as a reference, which is much more stable and less sensitive to volcanic activity. After analyzing the records for the month of September over the past fifteen years (2000-2015), the results show an average reduction of 4.5 million square kilometers.
Encouraging News for the Future
Considering the fact that not all CFCs are equal and this modifies their degradation (some have already disappeared, others will remain for decades), the news is very encouraging. Several agencies, including NASA, reach similar conclusions: had it not been for the Montreal Protocol, the ozone layer would disappear between the years 2050 and 2060. Now, if this rate of recovery is maintained, it is most likely that in that future decade we will see a complete recovery. Slow, but a little better each time.
