We present the first European network of tree ring δ¹³C and δ¹⁸O, containing 23 sites from Finland to Morocco. Common climate signals are found over broad climatic‐ecological ranges. In temperate regions we find positive correlations with summer maximum temperatures and negative correlations with summer precipitation and Palmer Drought Severity Indices (PDSI) with no obvious species‐specific differences. Regional δ¹³C and δ¹⁸O chronologies share high common variance in year‐to‐year variations. Long‐term variations, however, exhibit differences that may reflect spatial variability in environmental forcings, age trends and/or plant physiological responses to increasing atmospheric CO₂ concentration. Rotated principal component analysis (RPCA) and climate field correlations enable the identification of four sub‐regions in the δ¹⁸O network ‐ northern and eastern Central Europe, Scandinavia and the western Mediterranean. Regional patterns in the δ¹³C network are less clear and are timescale dependent. Our results indicate that future reconstruction efforts should concentrate on δ¹⁸O data in the identified European regions.

New records of δ¹³C and Δ¹⁴C values in annual rings of pine and oak from different sites around the world were obtained with a time resolution of 1 yr. The results obtained for Europe (Poland), east Asia (Japan), and South America (Peru) are presented in this paper. The δ¹³C and radiocarbon concentration of α-cellulose from annual tree rings of pine and of the latewood of oak were measured by both accelerator mass spectrometry (AMS) and liquid scintillation spectrometry (LSC). The values of ¹⁴S, which represent decreasing ¹⁴C concentrations caused by the emission of CO₂ from fossil fuel use (Suess effect; Suess 1955), were calculated for each site. Low average ¹⁴S (about −0.4 to 0.8%) values for clean areas and high values (about 3.4–3.6%) for industrial and/or urbanized areas were noted. Records of the δ¹³C values obtained for pine and oak from Poland were used to reconstruct climate changes during the last 400 yr. The results clearly indicate the climate cooling during the periods of the Maunder minimum (1645–1715) and the Dalton minimum (1790–1820). The anti-correlation between the δ¹³C and Δ¹⁴C records during those 2 periods is clear if the ¹⁴C record is shifted toward older ages by 24 yr.