THE HOLE IN THE THEORY

The "hole" in the ozone layer above the Antarctic (actually only a temporary thinning) was discovered in 1985, and a special scientific expedition in 1986 brought back extensive data. A few days after you get this issue, the 1987 expedition will be on its way.

The hole appears only during a few weeks each year, around October. The 1986 data show the hole less pronounced than it was in 1985--to the dismay of the Cassandras, no doubt. Chlorine was indeed found in the Antarctic as it was in the remaining strato-sphere, but there is not one ounce of evidence to link it to man-made sources (whether CFCs or other); there is plenty of chlorine in volcanic eruptions and in every green plant. Nor does the hole indi-cate a global deficiency of ozone; preliminary evidence suggests that it is due to a redistribution, with the worldwide total remaining constant.

Why the Antarctic?

The first thing that comes to mind is electric particles spewed out by the sun. They are deflected by the earth's magnetic field into spirals that eventually end in the polar regions (causing Northern Lights in the Arctic, for example). However, the deflection north or south does not depend only on charge, so that the absence of a hole in the Arctic would have to be explained.

Next, unlike the northern polar region, which is mostly ocean, the Antarctic is a continent, with the coldest atmosphere on earth above it (-100 degrees C), and its chemistry differs significantly from the rest of the atmosphere. What exactly that does to the dynamics of the atmosphere and to the photochemistry in it cannot be explained by scientists who are still puzzled by many aspects of the ozone layer even without this complication.

It is therefore quite unknown whether the Antarctic anomaly is due to chemical or other causes, and if it is the former, whether man has any part in it.

That does not mean that it makes no difference what cause is the one preferred by speculators. Ascribe it to CFCs, industrial pollu-tion and to man's reckless greed for profits, and your theory is assured of wide publicity by a sympathetic press; otherwise you will have to do the slow, exacting and patient work of an honest scien-tist before you publish it in a respectable journal.