Food crop yields could drop significantly because most plants are sensitive to ultraviolet radiation. Productivity in ocean plants, our planet's single greatest source of oxygen, has already decreased, due, in part, to excess UV radiation. These dire predictions catalyzed global agreement on the Montreal Protocol, a 1987 treaty to phase out CFCs. Since it takes 10 to 20 years for CFCs to travel to the stratosphere, scientists had thought the size of the ozone hole would now be starting to level off. Yet this is clearly not the case.
Some scientists think that global warming is exacerbating the effect of ozone depletion.
While the increase in greenhouse gases has increased the temperature of the lower atmosphere, it may have decreased the temperature of the stratosphere. Cooler temperatures in the stratosphere allow the formation of ice clouds, which causes air to stagnate and increases the ability of CFCs to do their damage. Another possible cause of the increase in ozone destruction is variable weather conditions. In this case, the size of the hole will decrease as stratospheric CFC concentrations decline. Reference Ozone Hole Refuels Debate on Climate, Andrew Revkin, New York Times, October 10, 2000.