[en] As a result of a nuclear war, vast forest areas will go up in smoke - corresponding at least to the combined land mass of Denmark, Norway and Sweden. In addition to the tremendous fires burning for weeks in cities and industrial centres, fires will also rage across croplands and it is likely that at least 1.5 billion tons of stored fossil fuels (mostly oil and gas) will be destroyed. The fires will produce a thick smoke layer, drastically reducing sunlight reaching the earth's surface. Darkness would persist for many weeks, rendering any agricultural activity in the Northern Hemisphere virtually impossible if the war takes place during the growing season. Marine ecosystems are probably particularly sensitive to prolonged periods of darkness. It is also possible that severe, worldwide photochemical smog conditions would develop, with high levels of tropospheric ozone that would likewise interfere severely with plant productivity. Survival becomes even more difficult if stratospheric ozone depletions also take place. The authors conclude that not more than a small fraction of the initial survivors of a nuclear war in the middle and high latitude regions of the Northern Hemisphere could escape famine and disease during the following year. (U.K.)