Climate and climatology A historical perspective

The chemical era of abiotic photochemical transformation of the primordial atmosphere and oceanic water to form the organic molecules from which life could spring. 

The microbial era during which the first simple life-forms evolved, proliferated, and forever modified the atmosphere and environment. 

The geological era in which the physical reconfiguration of oceans and continents caused major deviations in the evolution of life and the atmosphere. 

The recent age, when humans appeared with the intelligence to exploit fully all of the capability to alter significantly the global atmosphere and environment. 

The concept of a spherical world is attributed to the Greek philosopher Pythagoras in the sixth century B.C. (see also Chapter 1.3.1). Based on this mathematical-astronomical definition, the ancient geographers, namely Ptolemy, introduced 24 climata, being zones between two parallel circles, for which the length of the longest 

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