Spectrum of climatic variations and their causal mechanisms

This paper surveys the history of the Earth's climate and deals with facts, techniques, and causes. A review of climatic history since the origin of the Earth demonstrates the changes and variability of our climate along different scales. These variations can probably be fully understood only when taking into account both external forcing and non-linear interactions between the components of the climatic system: atmosphere, oceans, cryosphere, lithosphere, and biosphere. At least, as far as boundary conditions and forcing are concerned for the 10⁸ to 10⁹ yr time scale, atmospheric composition, solar evolution, and tectonism have to be considered, while variations of the Earth's orbital elements, and subsequently of the insolation, best explain the glacial-interglacial occurrences during the Quaternary Period. For shorter time scales, volcanic dust, solar activity, sea surface temperatures, and atmosphere-ocean autovariations have to be taken into account. Furthermore, the man-made effects have now to be considered: atmospheric loading of dust and air pollution particles, changes in surface albedo, and mainly the increasing rise of atmospheric CO₂ and other trace gases adding to a greenhouse effect.This man-made warming effect of future CO₂ increase will probably emerge as a clearly recognizable trend against the background of natural climatic fluctuations by the end of this century. This carbon dioxide induced super-interglacial will be superimposed on the expected natural long-term cooling trend of the ice age chronology.