The World Avoided by protecting the ozone layer

There are several very interesting papers in literature that analyse a future world where ozone depleting substances were never regulated by the Montreal Protocol. This protocol signed in 1989 was the first international agreement on regulation of chemical pollutants, and it is widely considered the most successful environmental treaty. Newman et al (ACP, 2009) show that 17% of the globally-averaged column ozone is destroyed by 2020, and 67% is destroyed by 2065 in comparison to 1980. Ozone levels in the tropical lower stratosphere remain constant until about 2053 and then collapse to near zero by 2058. Morgenstern et al. (GRL, 2008) indicate that the Montreal Protocol has not only averted further damage to the ozone layer but has helped prevent significant regional climate change. In this sense, Molina et al. (PNAS, 2009) state that the strengthening of the Montreal Protocol can phase down the production and consumption of hydrofluorocarbons (HFCs) with high global warming potential. According the authors, this and other strategies may reduce the risk of abrupt climate change in the next few decades.