It was a dust storm across Mars in 1971 that made biologists wonder if nuclear war might endanger all life on planet Earth: marine as well as human. The question of whether there can be any winner in a nuclear war is arising more emphatically now in laboratories in the Soviet Union and the United States. A bold new theory states that with the explosion of even a fraction of the stored up arsenal of nuclear power presently on Earth, there will be a so-called ''nuclear winter,'' caused by a devastating dust storm of soot and smoke, like that observed temporarily on Mars.
The development of the dust storm, which will cut off sunlight, had not previously been visualized. Rarely has a revolutionary concept appeared so suddenly at what could be a critical historical juncture.
It was publicly aired at a conference of 100 natural scientists here Oct. 31 -Nov. 1, and repeated last week at a meeting sponsored by Sens. Edward M. Kennedy (D) of Massachusetts and Mark O. Hatfield (R) of Oregon, with four leading US and four front-rank Soviet scientists participating.
Putting ideology aside, they argued that under the new postulates life might become impossible on Earth in a nuclear war. Not even cockroaches and other insects could adjust.
''The new results of findings on climate catastrophe seem to raise the stakes of nuclear war enormously,'' testified Carl Sagan of Cornell University. Arguing that nuclear weapons may precipitate calamity on all countries, he said, ''The possibility has arisen that, past a certain point, more nuclear weapons do not increase national security.''
E. P. Velikhov, vice-president of the Soviet Union's Academy of Sciences, discussed new research findings in the USSR similar to those in America. Nuclear war, accompanied by the release of radioactivity, toxic smoke, and drought, would black out sunlight for many months, he said, causing temperatures to fall precipitously around the world, killing plants and animals.
Until now, said Sergei Kapitza of the Moscow Physico-Technical Institute, it was arguable that nuclear arsenals deterred nuclear war as a ''tacit mutual hostage arrangement between the opposing nuclear powers.'' No longer, he argued. He agreed with US counterparts that recent findings mean that use of nuclear weapons is ''suicidal.''