6 - The conditions in Africa and Eurasia during the last glacial cycle

Summary

The global pattern

In this chapter I will focus my attention particularly on temperate and boreal Europe, the Mediterranean and Africa, which are the key areas that will be examined in Chapter I with regard to the Neanderthal extinction and the colonisation by Moderns. In Chapter 3 I described the pattern of increasing global climatic deterioration and instability during the Pleistocene. This progressive deterioration led, for example, to the contraction and extinction of tropical and sub-tropical woodland in southern Europe and to the rise of xeric species that culminated with a maximum expansion during the Last Glacial Maximum (LGM) (Carrion et al., 2000). Smaller scale patterns, as will be discussed in this chapter, have to be viewed within these larger-scale climate trends at the scale of millions of years (Webb & Bartlein, 1992). The progressive glaciation of the northern hemisphere commenced towards the end of the Pliocene although cooling started as early as the Eocene. The Quaternary is characterised by the alternation of cold glacial and warmer interglacial periods. There were at least nine glacial–interglacial cycles between 2 Myr and 700kyr (Shackleton & Opdyke, 1973, 1976; Shackleton et al., 1984) with at least 10 after that (Imbrie et al., 1984). Interglacials, which were often brief, started and finished abruptly (Flohn, 1984; Broecker, 1984), and characterised only 10% of the Pleistocene (Lambeck et al., 2002a & b). The amplitude of the climatic oscillations was lower prior to 735kyr (c. 41kyr) than after (c. 100kyr) (Ruddiman et al., 1986).