This book deals with what is popularly called ''the greenhouse effect''. The starting point is the sun, and it is considered how the atmosphere and magnetic field of the earth protect us against the radiation from the outer space. The atmosphere contains gases in a quantity and a mixture that make conditions suitable for the life on the earth. We are dependent on the existing greenhouse effect, but are anxious that the emitted gases caused by human activities, will increase the temperature in an alarming degree. The book is addressed to all who have an interest in the nature and the environment. It may be used in colleges and in courses for environmental studies. It gives information to politicians and other people who have to make decisions in the management of the nature and the resources of the earth. 70 figs., 15 tabs.