First it was acid rain, then the ozone hole. Now, CO2 in the air is supposed to bring on a climate catastrophe. Is global warming really a threat, are the polar ice caps in danger of elting and are coastal areas of habitation under threat of a deluge? Do we therefore need an energy-CO2 tax? The author explains in straight-forward language what climatological research indicates about the following questions: • What is and how does the greenhouse effect work? What does that mean for life on earth? • Why is a rise in temperature feared? • How and for what reasons has climate changed over the centuries and what role was played by the greenhouse effect? • What do we really know about the effect of a growing concentration of greenhouse gases in the atmosphere and what do current computer programs make of that ? • How do plants and algae cope with increased CO2 and temperature through photosynthesis?