Ask A Scientist© Environmental Science Archive

Author:     kentner
Text:       I am looking for some evidence that man has not significantly 
influenced the ozone layer, with the use of CFCnd carbon dioxide.

Response #: 1 of 3
Author:     Mark Fernau
Text:       First of all, carbon dioxide does not influence the ozone layer so 
you do not need any evidence for that. The only real evidence that CFCs are 
not hurting the ozone hole is that we did not measure Antarctic ozone until 
fairly recently so even though the "hole" has gotten worse, we have no clue 
what it was like before measurements. I am not sure that would hold up in 
court). There is evidence that ozone in the rest of the world is decreasing, 
but not as fast as people expected. -Again, a fairly weak argument. Many 
scientists feel that CFCs are guilty but you may find some that could give you 
contrary evidence.

Response #: 2 of 3
Author:     Don Libby
Text:       We know that CFCs cause the destruction of ozone in the presence 
of sunlight, and we know that CFCs are produced by human industry, and we know 
that CFC concentrations in the upper atmosphere have risen while ozone 
concentrations have fallen. There is sufficient evidence to attribute some of 
the ozone depletion to human activity. However, there may be other chemical 
agents capable of depleting ozone that come from natural processes, which 
could add to the rate of depletion. Perhaps some of our atmospheric chemists 
could comment on the proportion of variance in ozone depletion accounted for 
by rising CFC concentrations?

Response #: 3 of 3
Author:     Mark Fernau
Text:       It has been suggested and there is some evidence that the Pinatubo 
eruption increased the ozone loss last year in Antarctica. Also there is 
increasing interest in the probability that methyl bromide, a pesticide, is 
causing as much depletion as are CFCs.