IT HAS BEEN 10 years since the first fears were raised about the destruction of the planet's protective layer of ozone. Since then, its fate has played a major role in this country's decision not to build a supersonic airplane and in the debate over the space shuttle program and, last year, led to a ban on the manufacture of chlorofluorocarbons for use in aerosol sprays. This week, a long-awaited report from the National Academy of Sciences raised the basis for concern several notches higher by concluding that the ozone layer is being lost twice as fast as was predicted three years ago. It also predicted that if other industralized countries continue to release these compounds at an increasing rate, eventual ozone depletion would very likely be four times as great as had been thought.

The academy's earlier estimate led to a nationwide production ban primarily because of fears that ozone depletion would lead to increased skin cancer, since ultraviolet rays from the sun would be less effectively screened out. Concerns about the sensitivity of vital crops and fish species to increased ultraviolet radiation and possible, though uncertain, effects on climate also contributed to the ban. Research done in the interim tends to strengthen all those concerns. Indeed, it is now thought by some that, in addition to their effect on the ozone layer, chlorofluorocarbons may directly cause an increase in global temperatures, in much the same way that carbon dioxide is thought to act.

At almost the same moment that it released its ozone study, the academy also finished an expert review of the magnitude and likely effects of increased carbon dioxide in the atmosphere. The report agreed with earlier predictions that the amount of carbon dioxide in the atmosphere is steadily increasing, that the increase is a direct result of using fossil fuels and of slash-and-burn agriculture, and that a doubling of carbon dioxide would raise the average global temperature by about three degrees. The report confirmed earlier caluclations that if the use of fossil fuels grows at its historical rate of 4 percent annually, the doubling would occur in about 50 years. The three-degree warming could lead to drastic shifts in agricultural patterns, to a rise in sea level of up to 20 feet, and to a variety of other unpredictable but probably massive changes.

What should be done?So far the government bureaucracy has been reluctant to face up to the consequences of carbon dioxide buildup -- and for very understandable reasons. The energy problem is already bad enough without further limiting the options because of the long-range effects of increased use of fossil fuels. Heavier reliance on coal and on synthetic fuels seems to many to be the country's only energy salvation, especially in light of nuclear power's shaky status. But refusing to deal with the problem now will only increase the eventual pain. If adjustments are going to have to be made in the country's energy plan, it would be preferable to know it sooner rather than later.

Both reports also highlight the urgency of initiating collective international action. So far no other country has followed the U.S. lead in banning chlorofluorocarbons, though several are studying it. Clearly, neither problem can be successfully tackled without international cooperation. While the prospects for such a venture are admittedly dim, the risks of not acting are, in the wake of the academy's reports, undeniably high.