520 year record of summer sunshine for the eastern European Alps based on stable carbon isotopes in larch tree rings

• Published in: Climate dynamics Vol. 43; no. 3-4; pp. 971 - 980
• Main Authors: Hafner, Polona, McCarroll, Danny, Robertson, Iain, Loader, Neil J, Gagen, Mary, Young, Giles HF, Bale, Roderick J, Sonninen, Eloni, Levanič, Tom
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-08-2014; Springer Berlin Heidelberg; Springer; Springer Nature B.V
• Subjects: altitude; Carbon; Carbon dioxide; Carbon isotopes; Cellulose; climate; Climatology; Climatology. Bioclimatology. Climate change; Daylight; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Environmental aspects; Exact sciences and technology; External geophysics; Fractionation; Geophysics. Techniques, methods, instrumentation and models; Geophysics/Geodesy; growth rings; Isotope fractionation; Isotopes; Larix decidua; Meteorology; Oceanography; photosynthesis; Radiocarbon dating; solar radiation; stable isotopes; Summer; Sunshine; temperature; time series analysis; Trees; Alps; Southern Europe; Slovenia; Eastern Europe; Europe; Eastern Alps; United Kingdom; Climate change; Cloud cover; Dendrochronology; Carbon isotopes; Dendroclimatology; stable isotopes; Historical reconstruction; Larix decidua; Century 19th; Century 17th; Summer; Century 18th; Century 16th; insolation; Century 20th; Tree ring; Atmospheric temperature; Gymnospermae; isotope fractionation; Coniferales; Spermatophyta; climate change
• ISSN: 0930-7575; 1432-0894
• DOI: 10.1007/s00382-013-1864-z

A 520-year stable carbon isotope chronology from tree ring cellulose in high altitude larch trees (Larix decidua Mill.), from the eastern European Alps, correlates more strongly with summer temperature than with summer sunshine hours. However, when instrumental records of temperature and sunshine diverge after AD1980, the tree ring time series does not follow warming summer temperatures but more closely tracks summer sunshine trends. When the tree ring stable carbon isotope record is used to reconstruct summer temperature the reconstruction is not robust. Reconstructed temperatures prior to the twentieth century are higher than regional instrumental records, and the evolution of temperature conflicts with other regional temperature reconstructions. It is concluded that sunshine is the dominant control on carbon isotope fractionation in these trees, via the influence of photosynthetic rate on the internal partial pressure of CO₂, and that high summer (July–August) sunshine hours is a suitable target for climate reconstruction. We thus present the first reconstruction of summer sunshine for the eastern Alps and compare it with the regional temperature evolution.