Natural climate variability inferred from cosmogenic isotopes and other geophysical data and its impact on human activity

This paper discusses how natural climate changes may have influenced anthropological development. The main characteristics of solar variablity are reviewed: (1) as measured in detail over recent decades by instruments on-board artificial satellites; (2) as recorded in historical documents on the time-scale of centuries; and (3) as inferred on millennial time-scales from archived records of the cosmogenically generated isotopes C-14 and Be-10. The older, proxy data comprise temperature changes reconstructed from tree ring studies and environmental changes deduced from multidisciplinary studies of lake sediments. The effects of changes in ocean circulation and the sporadic influence of volcanic activity are also considered briefly.