The decline of Late Bronze Age civilization as a possible response to climatic change
The disintegration of Eastern Mediterranean civilization at the end of the late Bronze Age (late thirteenth and twelfth centuries B.C.) has traditionally been attributed to the irruption of new peoples into this area. However, the nearly contemporaneous decline of highly organized and powerful states in Greece, Anatolia, Egypt, and Mesopotamia warrants consideration of possible environmental causes likely to operate over sizable areas, especially since archaeological research has not succeeded in establishing the presence of newcomers at the onset of the Bronze Age disturbances.
Climatic change is a particularly attractive candidate since temperature and precipitation variations persisting over relatively short times can adversely affect agricultural output. Carpenter (1966) argued that the Mycenaean decline and migrations in and from Greece in the late thirteenth century were caused by prolonged drought and not the incursion of less civilized Dorian tribes. Donley (1971) and Bryson et al. (1974) have presented evidence of a spatial drought pattern which occurred in January 1955 that might be invoked to support this thesis. Population movements in Anatolia at the same time, though not as well established, can be delimited to some degree by the distribution of Hitto-Luwian peoples in the late ninth century B.C. It is hypothesized here that a drought induced migration of Luwian peoples from Western Antolia occurred early in the twelfth century B.C., that it was associated in some fashion with the invasion of Egypt by the ‘Sea Peoples’ in the reign of Ramesses III, and that the defeated remnants of these peoples settled along the Levantine coast and filtered into North Syria and the upper Euphrates valley.
It has been suggested that past climatic patterns recur in the present epoch but with a possibly different frequency. To establish that a spatial drought analogue to the above hypothesized migration can occur, temperature and precipitation records from 35 Greek, Turkish, Cypriot, and Syrian weather stations for the period 1951–1976 were examined. The Palmer drought index, an empirical method of measuring drought severity, was computed for each of these stations for the period of record. Since wheat yields tend to be highly correlated with winter precipitation for the area in question, the drought indices for the winter months were subjected to an empirical eigenvector analysis. An eigenvector (drought pattern) consistent with the postulated population movements in Anatolia occurred within the modern climatological record and was found to have been the dominant pattern in January 1972. The potential problems of eigenvector analysis in investigating problems of this type are discussed.