''Caution, not panic.'' That's the perspective with which both the US government and the public at large should view the possible climate-changing effects of the carbon-dioxide (CO2) gas released by burning coal, natural gas, and oil, according to the National Academy of Sciences.
This advice, embodied in the latest academy study of this climatic issue, contrasts strikingly with the tone of comments from the Environmental Protection Agency (EPA) when it released its own CO2 report Oct. 17.
While most atmospheric scientists agree that CO2 accumulating in the atmosphere probably would warm the Earth, the degree, timing, and possible consequences of that warming remain speculative. Yet the EPA suggested there could be a significant impact within a decade or so. It also repeated longtime speculation that the melting of polar ice caps could cause sea-level rises that would devastate many coastal areas. All of this carried the implication that drastic action may be needed in this century to curb the use of fossil fuels.
Some scientists outside the agency, including presidential science adviser George A. Keyworth, have already criticized the EPA position as needlessly ''alarmist.'' By contrast, the statement the academy issued with its report Friday has a much calmer tone.
The study was carried out by the National Research Council (NRC), the academy's operating arm. The council noted that ''uncertainty about both the scientific understanding of CO2 climate effects and the economic and social variables that might affect the use of fossil and synthetic fuels . . . argue against major policy changes at this time.''
The NRC report itself concludes: ''In our judgment, the knowledge we can gain in coming years should be more beneficial than a lack of action will be damaging; a program of action without a program of learning could be costly and ineffective.'' The report adds that what is needed now is ''research, monitoring , vigilance, and an open mind.''
Both reports do, in fact, emphasize the need for more research. They both stress the scientific uncertainties in trying to project the possibilities for CO2-induced climatic change. These include lack of knowledge of how CO2 is absorbed and released by the oceans, how general cloudiness might change to compensate for a warming effect, and how fossil-fuel usage itself will develop in the future.
With caveats such as these, the NRC study concludes that atmospheric CO2 levels ''most likely'' will double by late in the next century. This, the NRC study adds, could lead to rises in the planet's average temperature of between 1 .5 to 4.5 degrees C. (2 to 8 degrees F.), with the lower half of that temperature range being more probable. Warming would likely be strongest in polar regions.
The NRC acknowledges that such a climatic change would have ''few or no precedents in the Earth's recent history.'' Thus it does not dismiss the possibility of significant shifts in precipitation patterns or of eventual sea-level rises that might flood low-lying areas. However, the NRC urges that a premium be placed on gaining the knowledge to assess the climatic prospects more surely. It warns against raising fears based on lack of knowledge.
In fact, the EPA report itself makes much the same point. It is the ''alarmist'' tone with which the EPA issued its report that has put off many outside experts. They see it more as an attempt to preempt media attention before the academy study was issued than an exercise in informing the public. As one atmospheric scientist remarked off the record, '' 'Crying wolf' is a disservice'' in what should be a serious consideration of a serious subject.