Sir, - Jonathan Shanklin of the British Antarctic Survey terms my skeptical essay on CFCs and ozone depletion as 'one-sided' (C&I 1994, 282), apparently because I do not follow the 'accepted scientific consensus'. Later, he claims that 'some recent studies have linked a decrease in phytoplankton . . . with the Antarctic ozone hole,' but neglects to tell that other studies (by O Holm-Hansen, for example) do not confirm such a connecton. So much for 'one-sidedness'.

It is disingenuous of Shanklin to mix up the transient Antarctic ozone hole (a genuine phenomenon, but not predicted by the CFC-ozone theory) with a long-term global depletion trend. The latter can only be established after we have a longer data set from satellites, because there is indeed a sunspot connection and, therefore, an irregular 11-year cycle of ozone, and much other natural variability.

There certainly is also a volcanic influence on ozone, albeit sporadic and temporary. Because of Pinatubo, we saw a lowering of global ozone content during 1992-93, which is also quite apparent from Shanklin's chart. I am wiring to bet though that 1994 will show a return to higher Antarctic ozone values rather than a further downward trend.

Shanklin cites support from the UIC Stratospheric Ozone Review Group's (SORG) report, issued last February and warmly endorsed by a minister of state for the environment. Let me mention just one of the many problems with the report. SORG gives credence to a scientific paper that claims an increasing trend in UV radiation of 35% per annum! This result, as will be shown in a forthcoming issue of Science, is based on an invalid statistical analysis.

As the public begins to question the reality of the ozone 'threat' and the wholesale abandonment (at great cost) of a wide range of very useful chemicals, look for more distortion of the science to justify what has now become an established policy backed by an international treaty.

S. Fred Singer
Science & Environmental Policy Project
Washington DC