Stability of climate signal in carbon and oxygen isotope records and ring width from Scots pine (Pinus sylvestris L.) in Finland

Four hundred year long records of carbon and oxygen stable isotope ratios and ring width were measured from Scots pine (Pinus sylvestris U from sites in Northern and Eastern Finland. Responses of isotope ratios to temperature and precipitation were analysed for the 20th century. Carbon isotope ratios responded strongly to summer temperature at both sites, whereas all influence of precipitation oil the record was observed only at the site in Eastern Finland. Oxygen isotope ratios were less responsive to climatic variation than carbon at the high-frequency level. To shed light on the role of the possible divergence problem during last decades the climate responses were Studied separately in the first and in the second half of the 20th century. The responses to temperature were stable in the north but in Eastern Finland the significant period Of Summer occurred earlier during the later half of the century. Relationships between records were Studied during the 400 a period. All proxies correlated positively with each other, although temporal changes Occurred. Common forcing, discovered in Northern Finland between carbon isotope and ring width records, was weaker in the earlier period studied. Three climate reconstructions were created: temperature reconstruction for Northern Finland and temperature and precipitation reconstructions for Eastern Finland. Copyright (C) 2009 John Wiley & Sons, Ltd.