One of the real fears in the later years of the Cold War was the impact of a 'Nuclear Winter' on Mankind. The whole concept of a 'Nuclear Winter' only became publicly apparent in the 1980's and had its supporters and its detractors. However, for a short time the whole idea of a nuclear winter caught the public imagination to such an extent that the BBC produced a television programme based around a nuclear attack on the city of Sheffield and what happened to the area around the city once a nuclear winter had set in.
By 1985, the total explosive power of all the nuclear weapons held by countries was estimated to be between 12,000 and 20,000 megatons. The superpowers of the USA and the USSR kept their actual nuclear strength secret but various bodies such as the International Institute for Strategic Studies concluded that the world's stockpile of nuclear bombs was in the range of 12k to 20k megatons. To give some idea of what these figures represent, the explosive power of 'Little Boy' - which devastated the city of Hiroshima in August 1945 - was dwarfed by nuclear weaponry. A one- megaton bomb would have produced the explosive power of 80 'Little Boy' bombs. Therefore 12 thousand megatons would have been the equivalent of 960,000 'Little Boy' bombs and 20 thousand megatons would have been 1,600,000. Some scientists believed that just a fraction of these bombs would have thrown up enough dust and detritus after an explosion that would have blocked out the light of the sun. The estimated figure was that at 10 miles above the Earth's surface, 74% of the Sun's light would be blocked.
In 1983, a conference on the issue of a nuclear war was organised by American scientists. The conference was titled 'The Long-Term Worldwide Consequences of Nuclear War'. It concluded that a nuclear war would involve the use of 5,000 megatons of nuclear bombs. These bombs would produce 225 million tons of smoke alone. The darkness created by these explosions would last for weeks and even months. Without the rays of the Sun penetrating through to the Earth's surface, daily temperatures away from the coast would fall to -15 to -25 degrees Celsius. This was the 'nuclear winter'; crops would not grow; farm animals would die from radiation poisoning as would people. Areas throughout the world unaffected by actual bomb explosions would be affected by the 'nuclear winter' as the winds would carry radiation worldwide. Once the dust had settled the Sun's rays would once again get to ground level. However, the ozone layer would have been so weakened that much higher ultra-violet radiation would cause severe damage to the immune system to those humans who had survived.
Scientists at the conference estimated that just 8 days after a nuclear attack, world temperatures would have collapsed with even sub-Saharan Africa and the Amazon Basin experiencing daytime temperatures that would hover around the 0 degrees Celsius mark. The conference concluded with the following conclusion:
“In the aftermath of a 5,000 MT nuclear exchange, survivors would face extreme cold, water shortages, lack of food and fuel, heavy burdens of radiation and pollutants, diseases, and severe psychological stress - all in twilight or darkness. It is clear that the ecosystem effects alone resulting from a large-scale thermo-nuclear war would be enough to destroy civilisation as we know it in at least the Northern Hemisphere. These long-term effects, when combined with the direct casualties from the blast, suggest that eventually there might be no human survivors in the Northern Hemisphere. Human beings, other animals, and plants in the Southern Hemisphere would also suffer profound consequences.”