The necessity of eliminating the possibility of a large-scale nuclear conflict from the future of mankind is the most important problem of our times. There is no doubt that the probable aftereffects of such a conflict would by many times exceed the damage caused by the First and Second World Wars, the greatest in history. The question of the scale of the damage that would be inflicted upon liv ing nature by nuclear weapons has, however, not yet been fully clarified. It is clear that this damage would not be local, i.e., restricted to destruction in only the places of nuclear explosion. As a result of nuclear detonations, the atmosphere and hydrosphere would receive many harmful substances, including the radioactive waste products of nuclear reactions. These substances can be transferred by air flows and water currents over long distances, thus considerably increasing the area of harmful influence of nuclear bursts. There is no doubt that the indirect effects of nuclear warfare would inflict enor mous damage on mankind, since the present human society can only exist by a complicated system involving the production of foodstuffs, manufactured goods, medical supplies, etc. The destruction of even separate but important links of this system would bring about starvation, epidemics, and other calamities, which would spread to areas not directly involved in the nuclear conflict."

The authors of this book have studied the changes in the chemi cal composition of the atmosphere during geological history with regard to its close relationship to the evolution of the Earth's sedimentary shell. Beginning in 1977, the initial results of this study have been published as articles and parts of several monographs. Since new material clarifying atmospheric evolution have been obtained recently, the necessity has arisen to write a book treating the major results of investigations of the history of the atmosphere. In this book much consideration is given to the interrelation between the evolution of animate nature and changes in atmospheric composition. It proved be necessary to study the history of the two components of atmospheric air: carbon dioxide and oxygen. Attempts have been made to repre sent quantitatively the conclusions drawn here, i. e. to determine by calculation the changes in the amount of carbon dioxide and oxygen over much of the history of the atmosphere. These calculations, performed in most detail for the Phanerozoic and to a lesser degree for the Late Precambrian, are supplemented with estimates of changes in the chemical composition of the atmosphere in the Early Precambrian. Comparisons have been drawn between the changes in the chemical composition of the atmosphere and the development of animate nature, a close relationship being found to exist between the stages of the evolution of organisms and variations in the chemical composition of the atmosphere."