1.   Some estimates suggest that CFCs direct contribution to the greenhouse effect might be more or less offset by their indirect effect of countering it by depleting ozone.

2.   They calculate that ozone is depleted fastest when the sun is least active.

3.   Andrew Blustein of Oregon State University is looking at the possibility that some species lack a natural defense against ultraviolet radiation, making them vulnerable where ozone is depleted.

4.   The chemical in the refrigeration system also depletes the ozone but they have found a substitute for that.

5.   They are using HFCs, which do not deplete the ozone but do add to global warming.

6.   Chemical emissions are depleting the ozone.