24 European annually resolved stable isotope chronologies have been constructed from tree ring cellulose for the last 400 years (1600CE – 2003CE) for carbon and oxygen and for the last 100 years for hydrogen. Data was produced within the ISONET project (400 Years of Annual Reconstructions of European Climate Variability Using a Highly Resolved Isotopic Network,) to initiate an extensive spatiotemporal tree-ring stable isotope network across Europe funded as part of the fifth EC Framework Programme “Energy, Environment and Sustainable Development”. This data set comprises the ISONET δ18O records.

Wood increment cores of 15 or more Pinus sylvestris, Quercus robur/petraea or Cedrus atlantica tree individuals were taken. Dendro-dated tree-ring material of 4-5 individuals per site was dissected and pooled year by year. After cellulose extraction and homogenization, 18O/16O-ratios of annually resolved samples were determined by Isotope Ratio Mass Spectrometry (IRMS). Time series of 18O/16O are given as d-values versus SMOW. Details can be found in the downloadable “data description” file.

The ISONET project has been striving to improve greatly our understanding of European climate systems providing independent quantitative data for model verification and policy making. A network of 24 sites provides dendrochronological coverage from Iberia to Fennoscandia, Caledonia and the Tyrol. The stable isotope (C, H, O) ratios of these annually resolved time series shall be analysed within this project, to reconstruct past climate regimes (temperature, relative humidity and precipitation characteristics) for the last 400 years. Climate variability shall be addressed on three timescales; decade-century (source water/air mass dominance); inter-annual (quantifying baseline variability, extreme events and recent trends); and intra-annual (high resolution exploration of seasonality signals within tree-rings). ISONET goes far beyond existing tree-ring analyses in its spatial based investigation and interpretation (see also https://cordis.europa.eu/project/id/EVK2-CT-2002-00147).