Lake-level fluctuations at Ljustjنrnen, central Sweden and their implications for the Holocene climate of Scandinavia

A detailed reconstruction of water-level fluctuations in Ljustjärnen, a small kettle lake in south-central Sweden, provides a preliminary outline of Holocene changes in water balance for that region. Lake-levels were generally high from 9200 to 8000 yr B.P., falling from then until c. 6500-6000 yr B.P., and rising again by 5000 yr B.P. Temporary lowerings were recorded c. 4000 yr B.P. and c. 2000 yr B.P., and water levels have risen dramatically since c. 500 yr B.P. The reconstruction is based on sedimentologic and fossil analyses of multiple cores, as well as on geomorphological evidence. Comparison of lake-level fluctuations in south-central Sweden with those from southern Sweden and western Finnish Lapland, and with records of glacier fluctuations in the Scandinavian Mountains suggest a distinct north-south contrast in water balance from 9000 to 5000 yr B.P., consistent with strongly zonal atmospheric circulation during that period. Between 7000 and 5000 yr B.P. the mid-Holocene dry period appears to have been time-transgressive across Scandinavia, perhaps as a result of a gradual shift in the position of the Atlantic Polar Front and its associated cyclonic stormtrack. Since 4000 yr B.P., however, most detectable fluctuations are synchronous across Scandinavia, with the most prominent and widespread change being increased net moisture during the “Little Ice Age”.