Singer wrote in 1995,
<< For the general public, and even for the trained scientist, these
scientific controversies are difficult to sort out. It is indeed a
multi-faceted problem, a chain with many links connecting the release of
CFCs into the atmosphere with the occurrence of skin cancer. Briefly,
the steps are postulated as follows (6):
1. CFCs with lifetimes of decades and longer become well-mixed in the
atmosphere, percolate into the stratosphere, and there release chlorine.
2. Chlorine, in its active form, can destroy ozone catalytically and
thereby lower its total amount in the stratosphere.
3. A reduced level of ozone results in an increased level of solar
ultraviolet radiation reaching the surface of the earth.
4. Exposure to increased UV leads to increases in skin cancer.
Each of these four steps is controversial, has not been sufficiently
substantiated, and may even be incorrect (7,8). One can reasonably
conclude that policy is rushing far ahead of the science. >>
William Connolley is picking apart #1 above (the well-mixed point).
The context of the discussion is the POLITICAL controversy over the CFC
ban. Singer says it's not justified, because NOT ALL of the 4 points in
the chain of reasoning are correct. If even one is incorrect, he argues,
then the Montreal Protocol was unjustified.
It's basically Singer's POV vs. Connolley's POV. Lots of
environmentalsts side with Connolley, and lots of others side with
Singer.
Many of the environmentalists try to bolster their argument by saying
that "the consensus of scientists" agrees with them. But I don't think
Wikipedia ought to support the claim that such a "consensus" exists.
Now if someone did a survey, and 95% of scientists agreed on a point, we
could arguably call that a "consensus" (as we have done on evolution:
95% of all scientists (not just biologist) surveyed support Darwin's
theory, and well over 99% of biologists.
I'm getting tired, so I'll see you guys tomorrow...
Uncle Ed