Original paper

Scandinavian climate since the late 18th century reconstructed from shells of bivalve mollusks

Schöne, Bernd R.; Dunca, Elena; Mutvei, Harry; Baier, Sven; Fiebig, Jens


We present a revised, more robust summer (June–August) air temperature proxy record from variations in annual shell growth rates of the freshwater pearl mussel Margaritifera margaritifera (L.). Shell oxygen isotope profiles resemble the temperature range of about 7 to 8°C during the growing season and confirm the annual periodicity of shell formation. Based on similar growth patterns, 60 contemporaneous specimens (individual ages ranging from ten to 127 years) with overlapping life-spans were assembled to form a 216-year master chronology (AD 1777–1992). Age-detrended, standardized and pre-whitened annual growth rates and air temperature (river water temperature during summer closely coincides with air temperature) exhibit a significant positive correlation (R2 = 0.60, p <0.0001) and high running similarity confirming previous experimental findings. a linear growth-temperature model can reconstruct summer air temperature from annual shell growth increments with a precision error of better than ± 0.95°c (p <0.05) and verify dendrochronological reconstructions. proxy (shells, trees) and available observational summer air temperature records from scandinavia do not resemble the global surface temperature rise over the last 140 years. however, in scandinavia, extremely cold summers occurred less frequently after ca. 1930 than before.Freshwater pearl mussels provide an independent measure for temperature changes in the pre-instrumental era capable of verifying and complementing other proxy archives.


bivalve mollusksclerochronologyisotopesclimate changedendrochronology