Climatic Changes and Biotic Events

A single multistage system of climatic variations from short-term (a few tens and hundreds of thousands of years) to superlong ones (several hundred million years) which existed during the Phanerozoic is evidence of the diversity and persistence of the factors governing climatic changes. This provides principal possibility to recognize and identify these factors according to the specific character of oscillations. In addition, knowledge of the structure of climatic oscillations will permit the long-term natural components of recent climatic trends to be estimated more exactly and mathematical models of climate to be made more real. The global, synchronous, and in-phase character of climatic oscillations of various ranks indicate that these oscillations are connected with changes in the Earth’s thermal balance rather than with heat redistribution in the biosphere. Thus, the circle of possible causes of climatic oscillations becomes much narrower and the search for them becomes easier. The main difference between glacier intervals of geological history and interglacial stages was a great increase in the amplitudes of climatic oscillations. This seems to be related to the periodic appearance and fluctuations of multi-year cryophase with superposition of minima of various rank. Climatic changes can govern biotic events or only provoke them. In the first case, the scales of biotic changes are determined, as a rule, by the magnitude, and the spatial and temporal scales of climatic changes. In the second case, there may be no direct relationship between the magnitude of climatic changes and the scale of a biotic event.