VATIS UPDATE Article

According to a new study published in the American Meteorological Society’s Journal of Climate, if the Montreal Protocol had been rejected and the risks of ozone depleting substances had been ignored by the world, we would be facing even more intense tropical cyclones in the near future. Using one of the most advanced atmospheric computer models available, scientists compared our expected future with a scenario in which Ozone-Depleting Substances (ODSs) had never been regulated.

When they looked at tropical storms, they found a striking difference: By 2065, the potential intensity of tropical cyclones was nearly three times greater in the scenario of a world without the Montreal Protocol. They found that the driver of that increasing potential intensity was almost exclusively the rise in sea surface temperatures due to the greenhouse gas effect of certain ODSs. “In this study, we show that the Montreal Protocol also mitigates the strength of hurricanes, not because it protects the ozone layer but because it reduces ODSs that warm the ocean surface,” said Lorenzo Polvani, at Columbia University, the United States.

In the new study, Polvani and his team, turned the question to hurricanes and tropical cyclones. They tested two scenarios: our current trajectory and the scenario of a world in which the Montreal Protocol had never existed. By using a computer model that takes into account land, ocean and sea-ice components and interactive stratospheric chemistry, the scientists could compare the changing forces behind hurricanes over several decades as ODSs increased. That finding has a bearing on research into the recent increases in tropical cyclone intensity. The study shows that even in a scenario where ozone losses are much larger than those over the past 30 years, the ozone loss did not affect tropical cyclone potential intensity.