Paleoclimatic potential of the northernmost juniper trees in Europe

Abstract

In late summer 2004 stem discs were collected from about 40 juniper trees ( Juniperus Siberica Burgsd) growing at the remote central part of Kola Peninsula behind the polar circle at the northern timberline. Up to now these juniper trees are oldest ones found at Kola Peninsula. Data processing was difficult due to extremely small tree rings as well as the occurrence of missing and false rings. However, finally it was possible to build up a 676-year long chronology and retrieve information on the past climatic variations at Kola Peninsula that could partly be linked to extraterrestrial factors such as changes in solar activity and galactic cosmic ray activity. It was obtained that: (1) There is a rather good agreement between long-term climatic variation in Europe and at Kola Peninsula. (2) The minima of solar activity Sporer (1416–1534 AD), Maunder (1645–1715 AD) and Dalton (1801–1816 AD) were accompanied by temperature decreases. Cooling during the end of the Wolf minimum (until 1350) is reflected in the juniper tree-ring series from Kola Peninsula whereas it is not reflected in the European temperature reconstructions. (3) Some recent decreases in solar activity around 1900 and 1960 are linked to phases of reduced growth in juniper. (4) The juniper chronologies from Kola Peninsula do not indicate a temperature rise at the end of the XX century. (5) MTM spectral and wavelet analysis of juniper tree-ring records showed: (a) more pronounced 22- and 80–100-year periodicities; (b) the main cycle of solar activity, the 11-year Schwabe cycle, was not present; (c) 20–22-year periodicity was not significant throughout the entire ca.700-year period, but during certain time intervals: 1328–1550, 1710–1800, 1985 to present.