The nuclear twilight.

• Position: Third special Assembly on disarmament

It is a hot, humid summer night in Beijing, Moscow or New York. Windows are open to let in the warm, stifling air People shift and sweat in their beds, unable to sleep. But the city lies still in the heat. Suddenly, the night is torn apart by an apocalyptic blast-a nuclear explosion.

Tens of thousands are instantly killed from scorching nuclear heat. A hundred thousand suffer from deadly radiation burns and sickness. There's no electricity, no water. Untainted food is scarce. Scenes of carnage fill the hospitals. Violent fires rage throughout the city, sending up a thick cloud of smoke and soot. An unexpected wind spreads the radioactive fall-out to distant communities.

It is now morning. But the city remains in darkness, shrouded by a densely black sky. Temperatures quickly drop. On the third day of darkness, water spilled by firemen desperately trying to put out the nuclear fires starts to freeze on the sidewalks.

Extreme cold and darkness continue for a month, not only in the targeted cities, but in a large part of the planet. The spectre of starvation rises in the second month: crops die from lack of sunlight and rain and from the cold. The nuclear war has already killed hundreds of millions of people. Its indirect effects on climate and heredity will now kill billions. Will Earth ever recover?

A lasting impact

The current scientific consensus is blunt: a large- scale nuclear war could have a lasting and disastrous impact on global climate.

"The risk would be greatest if large cities and industrial centres in the northern hemisphere were to be targeted in the summer months", concludes a study prepared for the United Nations by a group of experts on a predicted phenomenon called "nuclear winter". "The scientific evidence is now conclusive", the experts add.

Their 70-page report (A/43/351) on the climatic and other global effects of nuclear war analyses in detail current scientific research on the atmospheric and climatic consequences, the effects on natural ecosystems and agriculture and the health and socio-economic impact.

The term "nuclear winter" is not used in the report because the experts feel that "it does not do justice to the nature, extent and complexity of thc circumstances involved". Most of the planet's surface would not freeze as a result of a major nuclear war, but the global cumulative effects would be, nevertheless, "severe and extensive".

Less sunlight, lower temperatures and fewer rains would severely threaten world...