Gagen, M.

Grudd, H.

Irobertson, I.

Jalkanen, R.

Kirchhefer, A.

Loader, N.

McCarroll, D.

Young, G.

Zorita, E.

Jukuri

Geophysical Research AbstractsVol. 12, EGU2010-5385, 2010EGU General Assembly 2010© Author(s) 2010Reconstructing summer cloudiness from stable carbon isotope ratios intreeringsMary Gagen (1), Danny McCarroll (1), Eduardo Zorita (2), Giles Young (1), Håkan Grudd (3), Risto Jalkanen (4),Neil Loader (1), Iain Robertson (1), and Andreas Kirchhefer (5)(1) Swansea University, United Kingdom (m.h.gagen@swansea.ac.uk), (2) Dept. of Palaeoclimate, Institute for CoastalResearch, GKSS Research Centre, Geestacht, Germany., (3) Department of Physical Geography and Quaternary Geology,Stockholm University, Sweden., (4) Finnish Forest Research Institute, METLA, Rovaniemi, Finland., (5) Department ofArctic and Marine Biology, University of Tromsø, Tromsø, NorwayPalaeoclimate information from the annual rings of trees dominates research on climates of the last thousandyears because the proxy is unrivalled through its combination of geographical coverage, absolute dating and depthof study. The stable isotope treering proxies (carbon hydrogen and oxygen isotopes measured in wood celluloseextracted from annual rings) have received less attention by virtue of being relatively recent additions to the disci-pline. Treering stable carbon isotope ratios from northern Boreal sites have traditionally been used to reconstructpast changes in summer temperature. However, a summer temperature reconstruction based on stable carbon iso-tope ratiods in Pinus sylvestris from a site in northern Finnish Lapland (Gagen et al 2007) appears inconsistent withearly instrumental temperature series from the region. A further stable carbon isotope series from Pinus sylvestrissampled in Northern Norway reveals that, when the relationship between instrumental temperature and cloud coverin the region has diverged in the past, treering stable carbon isotope ratios infact record summer cloud cover nottemperature. Here we present summer cloud cover reconstructions from Norway and Finland revealing that cloudcover was diminished during cold centuries over the recent past. At these high latitude sites a negative short-wavecloud feedback is indicated.

Reconstructing summer cloudiness from stable carbon isotope ratios in treerings.

Reconstructing summer cloudiness from stable carbon isotope ratios in treerings.

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