ABSTRACT
The major world problems, chemical pollution of the atmosphere, waste proliferation and probable drastic climatic change all defer from a same cause. This chapter considers the transitional zone in the North of Africa and in particular the limit between the southern Sahara and the northern Sahel. At global scale, the Quaternary is characterized since some 2.4 million years by sharp, relatively short successions of cold and warm phases. Astronomical orbit related parameters constitute the major "forcing" of those wide climatic pseudo-periodicities. Geology, palaobiology, palaoanthropology and prehistory provide documented answers, since they yield efficient markers of the climatic parameters: Temperature, Wind and Precipitation. The process of global warming after the LGM was irregular with some short-term fluctuations, of which the most remarkable are the two "surges" of sea level rise at ca 14 and 11.5 ka, and the Younger Dryas cold episode at 11–10 ka.
