ARCHAEOLOGICAL AND PALEOECOLOGICAL INDICATIONS OF AN ABRUPT CLIMATE-CHANGE IN THE NETHERLANDS, AND EVIDENCE FOR CLIMATOLOGICAL TELECONNECTIONS AROUND 2650 BP

A sudden and sharp rise in the C-14 content of the atmosphere, which o ccurred between ca. 850 and 760 calendar yr BC (ca. 2750-2450 BP on th e radiocarbon time-scale), was contemporaneous with an abrupt climate change. In northwest Europe (as indicated by palaeoecological and geol ogical evidence) climate changed from relatively warm and continental to oceanic. As a consequence, the ground-water table rose considerably in certain low-lying areas in The Netherlands. Archaeological and pal aeoecological evidence for the abandonment of such areas in the northe rn Netherlands is interpreted as the effect of a rise of the water tab le and the extension of fens and bogs. Contraction of population and f inally migration from these low-lying areas, which had become marginal for occupation, and the earliest colonisation by farming communities of the newly emerged salt marshes in the northern Netherlands around 2 550 BP, is interpreted as the consequence of loss of cultivated land. Thermic contraction of ocean water and/or decreased velocity and press ure on the coast by the Gulf Stream may have caused a fall in relative sea-level rise and the emergence of these salt marshes. Evidence for a synchronous climatic change elsewhere in Europe and on other contine nts around 2650 BP is presented. Temporary aridity in tropical regions and a reduced transport of warmth to the temperate climate regions by atmospheric and/or oceanic circulation systems could explain the obse rved changes. As yet there is no clear explanation for this climate ch ange and the contemporaneous increase of C-14 in the atmosphere. The s trategy of C-14 wiggle-match dating can play an important role in the precise dating of organic deposits, and can be used to establish possi ble relationships between changing C-14 production in the atmosphere, climate change, and the impact of such changes on hydrology, vegetatio n, and human communities.