Torneträsk, Sweden 1100 Year Tree Ring d13C and Sunshine Reconstruction Loader, N.J.; Young, G.H.F.; Grudd, H.; McCarroll, D. Loader, N.J. Young, G.H.F. Grudd, H. McCarroll, D. Arctic Oscillation (AO) Other Reconstruction earth science/paleoclimate/climate reconstructions|tree ring (surface downwelling shortwave radiation,null,null,hour,Jun-Aug,climate reconstructions|tree ring,null,null,N,hour per day) earth science/paleoclimate/climate reconstructions|tree ring (surface downwelling shortwave radiation,null,null,hour,Jun-Aug,climate reconstructions|tree ring,null,null,N,scaled 1913-2006; hour per day) earth science/paleoclimate/climate reconstructions|tree ring (surface downwelling shortwave radiation,null,two standard deviations,hour,Jun-Aug,climate reconstructions|tree ring,null,null,N,hour per day) earth science/paleoclimate/tree ring (delta 13C,alpha cellulose,null,per mil VPDB,null,tree ring,corrected,isotope ratio mass spectrometry,N,corrected for the decrease in atmospheric δ13C values due to the rise in CO2 caused by fossil fuel combustion since the beginning of the industrialization) earth science/paleoclimate/tree ring (number of samples,null,null,count,null,tree ring,null,null,N,null) earth science/paleoclimate/instrumental (surface downwelling shortwave radiation,null,null,hour,Jun-Aug,instrumental,null,null,N,hours per day) earth science/paleoclimate/tree ring (delta 13C,alpha cellulose,one standard deviation,per mil VPDB,null,tree ring,corrected,isotope ratio mass spectrometry,N,null) earth science/paleoclimate/tree ring (age,null,null,year Common Era,null,tree ring,null,null,N,null) earth science/paleoclimate/reconstructions (Torneträsk d13C>LATITUDE 68.2>LONGITUDE 19.8) This paper presents results from the first 1100 years of a long stable carbon isotope chronology currently in development from Scots Pine (Pinus sylvestris L.) trees growing in the Torneträsk region of northern Sweden. The isotope record currently comprises a total of 74 trees with a mean annual replication of >12, thereby enabling it to be compared directly with other tree-ring based palaeoclimate reconstructions from this region. In developing the reconstruction, several key topics in isotope dendroclimatology (chronology construction, replication, CO2 adjustment and age trends) were addressed. The resulting carbon isotope series is calibrated against instrumental data from the closest meteorological station at Abisko (AD1913-2008) to provide a record of June-August sunshine for northern Fennoscandia. This parameter is closely linked to the direct control of assimilation rate; Photosynthetically Active Radiation (PAR) and the indirect measures; mean July-August temperature and percent cloud cover. The coupled response of summer sunshine and temperature in this region permits a multi-parameter comparison with a local reconstruction of past temperature variability based upon tree growth proxies to explore the stability of this coupling through time. Several periods are identified where the temperature (X-ray density) and sunshine (stable carbon isotope ratio) records diverge. The most significant and sustained of these occur between c AD1200-1380 and c AD1550-1780, providing evidence for a cool, sunny, two-phase "Little Ice Age". Whilst summer sunshine reconstructed for the 20th century is significantly different from the mean of the last 1100 years (P < 0.01), conditions during the early mediaeval period are similar to those experienced in northern Fennoscandia during the 20th century (P > 0.01), so it is the 17th-18th, and to a lesser extent, the 13th centuries rather than the early mediaeval period that appear anomalous when viewed within the context of the last 1100 years. The observed departures between temperature and sunshine are interpreted as indicating a change in large-scale circulation associated with a southward migration of the Polar Front. Such a change, affecting the Northern Annular Mode (Arctic Oscillation) would result in more stable anticyclonic conditions (cool, bright, summers) over northern Fennoscandia, thus providing a testable mechanism for the development of a multi-phase, time-transgressive "Little Ice Age" across Europe. STUDY NOTES: Reconstruction of summer (June-August) sunshine for northern Fennoscandia for the last 1,100 years based on carbon isotopes from Scot Pine tree rings from Torneträsk, Sweden. IITRDB007 NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Loader, N.J. Investigator : Young, G.H.F. Investigator : Grudd, H. Investigator : McCarroll, D. 2013-01-08 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/13674 https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/europe/sweden/tornetrask2013d13c.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/europe/sweden/tornetrask2013d13c.txt English https://www.ncdc.noaa.gov/paleo/study/13674 https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/europe/sweden/tornetrask2013d13c.txt Loader, N.J., G.H.F. Young, H. Grudd, and D. McCarroll. 2013. Stable carbon isotopes from Torneträsk, northern Sweden provide a millennial length reconstruction of summer sunshine and its relationship to Arctic circulation. Quaternary Science Reviews, Vol. 62, pp. 97-113. DOI: 10.1016/j.quascirev.2012.11.014 START YEAR: 900 AD * END YEAR: 2008 AD 19.4 68.1 20.2 68.3