Study: Montreal Protocol has Prevented Acute Changes in Earth’s Hydroclimate
A study published in the June 2013 issue of the Journal of Climate, conducted by Yutian Wu of New York University and Lorenzo M. Polvani of Columbia University, finds that the 1987 Montreal Protocol to the Vienna Convention for the Protection of the Ozone Layer has been critical in preventing major changes in Earth’s hydroclimate.
It has long been known that the Montreal Protocol has helped to slow global warming due to the near-elimination of chlorofluorocarbons (CFCs), a family of potent greenhouse gases. The Wu and Polvani study extends this analysis to Earth’s hydroclimate by using an IPCC AR-4 class atmospheric general circulation model to calculate the hydrological cycle and atmospheric general circulation changes associated with a “World Avoided” scenario (an Earth without the Montreal Protocol) for the years 2020-2029.
The study finds that severe ozone loss and CFC increases would have resulted in a “dry gets drier and wet gets wetter” pattern, similar to the effects expected from global warming. Generally, the model predicts that equatorial wet regions would become wetter without a Montreal protocol, that subtropical dry regions would become drier, and that mid- and high-latitude wet regions would intensify and move poleward due to shifts in Earth’s jet streams.
Although the study does not correct for the increased presence of hydrofluorocarbons (HFCs) in Earth’s atmosphere due to the replacement of CFCs by HFCs following the Montreal Protocol, the study offers a fascinating view of a climate that might have been, a climate that was avoided due to concerted action by the world’s nations. Further, the study is a stark reminder that humans can easily generate large-scale changes in Earth’s systems, destabilizing the human environment.