SOLAR INFLUENCES ON HOLOCENE CLIMATIC CHANGES ILLUSTRATED BY CORRELATIONS BETWEEN PAST LAKE-LEVEL FLUCTUATIONS AND THE ATMOSPHERIC C-14 RECORD

Chronological correlations established at different time scales among the lake-level fluctuations in the Jura and French Subalpine ranges, glacier movements in the Swiss and Austrian Alps, and the atmospheric 14C record during the last 7 millennia show coincidences between lake-level rises, glacier advances, and high 14C production and vice versa. These correspondences suggest that the short-term 14C variations may be an empirical indicator of Holocene palaeoclimates and argue for possible origins of Holocene climatic oscillations: (1) The varying solar activity refers to secular climatic oscillations and to major climatic deteriorations showing a ca. 2300-yr periodicity. (2) A question is raised about a relationship between the earth's magnetic field and climate. First, the weak-strength periods of the earth's dipole magnetic field (between 3800 and ca. 2500 B.C.) coincide with higher climate variability, and vice versa. Second, the ca. 2300-yr periods revealed by the 14C record and also by the major climatic deteriorations re. corded in Jurassian lakes (ca. 1500 A.D., ca. 800 B.C., and ca. 3500 B.C.) coincide with the ca. 2300-yr periods revealed by the earth's nondipole geomagnetic field. The present warming induced by anthropogenic factors should be intensified during the next few centuries by natural factors of climate evolution. © 1993 by Academic Press, Inc.