|The conclusion, conveyed with great authority by several big-league climatologists from government and private research organizations, is terrible: by the year 2000, the atmosphere and weather will grow warmer by several degrees and life - animal, plant, human - will be threatened. The experts say that melting ice caps, flooded cities, droughts in the corn belt and famine in the third world could result if the earth's mean temperature rises by a mere two or three degrees.|
PICKING up where a high-school chemistry class might end, ''Nova,'' the public-broadcasting science series, offers the nonmatriculating viewer an advanced course in worrying. The cause of the concern is all the carbon dioxide that's being pumped into the industrialized and motorized air. The hourlong broadcast is called ''The Climate Crisis: The Greenhouse Effect,'' at 9 tonight on Channel 13.
The documentary swings between pictures of green lands and smokestack skies. This, of course, is familiar to readers and documentary viewers, going back at least to Rachel Carson's ''Silent Spring.'' The pleasant educational lesson on ''Nova'' illustrates planetary ecology. In an interesting analogy, we learn from the writer-producer Richard Broad, of Boston's public-television station WGBH, that a single trans-Atlantic flight consumes all the energy that an acre of forest produces in 100 years. The oceans and forests absorb carbon dioxide; that's the good news. The bad news is that these natural safeguards could be imperiled if tropical forests are cut down for agricultural use.
Millions of tons of coal are burned annually around the world. In small amounts, carbon dioxide is necessary, but with the ever-growing consumption of fossil fuels (mainly coal), the air becomes polluted at an intolerable level. The scientists explain that the carbon dioxide released into the air acts like the glass in a greenhouse, sealing the earth in its own warmth - creating the ''greenhouse effect.''
Looking at the clouds of industrial smoke, and then at the crowded highways, a scientist from the National Center for Climate Research says: ''The industrialized West keeps the furnaces burning. This is the high price we pay for prosperity.'' It is a grim prognosis. The scientists on the program issue warnings but they cannot quite tell the world to stop the clock of industrialization. The advances made on antipollution devices on automobiles might be applied to cutting down industrial smoke, too.
''The Climate Crisis'' was originally produced by WGBH in 1983. It would be useful to do some re-editing, cut down a bit on the original documentary and bring it up to date, even if only with a brief new introduction or conclusion.