The Earth’s climate has, during its long history, oscillated between warm periods and cool periods, but the extreme ranges have remained within biological limits (Lovelock, 1982). Such oscillations have been attributed to a wide variety of natural phenomena such as perturbations in the Earth’s major orbital parameters, changes in the solar energy flux, changes in atmospheric gas components, changes in the particulate matter within the atmpshere such as volcanic dust, changes in ocean currents such as with El Niño, changes within biological life itself such as described by the Gaia hypotheses, changes in distributions of continents and oceans, and even combinations of several of these phenomena. The surface of the Earth is slowly but constantly being changed by geologic processes, and local weather and climate changes accordingly. The major cool periods of the past were, however, associated with times when there was land in a polar or subpolar position; warm periods were associated with times when land masses were in temperate or equatorial positions.
The space allotted for this short chapter does not permit discussion of a “normal” climate of the Earth, or even if the Earth has one. This short synthesis deals only with broad generalities, and gives a small sample of the various methods used to decipher our climatic changes during the Quaternary. Literature on this subject is vast and grows at a fast pace, but most of it concerns the Holocene and Wisconsin paleoclimatology; very little of it deals with pre-Wisconsin Quaternary.
The terrestrial system