Torneträsk Tree Ring MXD Temperature Reconstruction AD 500-2004 Grudd, H. Grudd, H. Air Temperature Reconstruction PAGES 2k Network PAGES Arctic 2k earth science/paleoclimate/climate reconstructions|tree ring (age,null,null,year Common Era,null,climate reconstructions|tree ring,null,null,N,null) earth science/paleoclimate/climate reconstructions|tree ring (temperature,ring density,null,degree Celsius,null,climate reconstructions|tree ring,anomalized,null,N,based on latewood density; deviation from 1951-70 mean) earth science/paleoclimate/climate reconstructions|tree ring (temperature,ring density,null,degree Celsius,null,climate reconstructions|tree ring,anomalized|filtered,null,N,based on latewood density; deviation from 1951-70 mean; 30-year filtered) earth science/paleoclimate/climate reconstructions|tree ring (temperature,ring density,null,degree Celsius,null,climate reconstructions|tree ring,null,null,N,based on latewood density) earth science/paleoclimate/tree ring (tree ring standardized growth index,null,null,null,null,tree ring,composited,null,N,null) earth science/paleoclimate/climate reconstructions|tree ring (temperature,ring density,null,degree Celsius,null,climate reconstructions|tree ring,anomalized|filtered,null,N,based on latewood density; deviation from 1951-70 mean; 100-year filtered) earth science/paleoclimate/reconstructions (Torneträsk>LATITUDE 68.25>LONGITUDE 19.6) This paper presents updated tree-ring width (TRW) and maximum density (MXD) from Torneträsk in northern Sweden, now covering the period AD 500-2004. By including data from relatively young trees for the most recent period, a previously noted decline in recent MXD is eliminated. Non-climatological growth trends in the data are removed using Regional Curve Standardization (RCS), thus producing TRW and MXD chronologies with preserved low-frequency variability. The chronologies are calibrated using local and regional instrumental climate records. A boot-strapped response function analysis using regional climate data shows that tree growth is forced by April-August temperatures and that the regression weights for MXD are much stronger than for TRW. The robustness of the reconstruction equation is verified by independent temperature data and shows that 63-64% of the instrumental inter-annual variation is captured by the tree-ring data. This is a significant improvement compared to previously published reconstructions based on tree-ring data from Torneträsk. A divergence phenomenon around AD 1800, expressed as an increase in TRW that is not paralleled by temperature and MXD, is most likely an effect of major changes in the density of the pine population at this northern tree-line site. The bias introduced by this TRW phenomenon is assessed by producing a summer temperature reconstruction based on MXD exclusively. The new data show generally higher temperature estimates than previous reconstructions based on Torneträsk tree-ring data. The late-twentieth century, however, is not exceptionally warm in the new record: On decadal-to-centennial timescales, periods around AD 750, 1000, 1400, and 1750 were equally warm, or warmer. The 200-year long warm period centered on AD 1000 was significantly warmer than the late-twentieth century (p < 0.05) and is supported by other local and regional paleoclimate data. The new tree-ring evidence from Torneträsk suggests that this "Medieval Warm Period" in northern Fennoscandia was much warmer than previously recognized. STUDY NOTES: Tree ring maximum density temperature reconstruction for AD 500-2004, based on a total of 100 pine trees from Torneträsk in northern Sweden. Sample materials cover the period AD 441–2004. Dry dead wood covers the period AD 441–1789 and living trees cover the period AD 1336–2004. No subfossil lake material is included in the MXD data. Torneträsk area, northern Sweden (68.21-68.31°N, 19.45-19.80°E, 350-450 m a.s.l.). NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Grudd, H. 2010-04-01 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/12037 https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/europe/sweden/tornetrask-temperature2008.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/europe/sweden/tornetrask-temperature2008.xls https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/europe/sweden/tornetrask-temperature2008.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/europe/sweden/tornetrask-temperature2008.xls English https://www.ncdc.noaa.gov/paleo/study/12037 https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/europe/sweden/tornetrask-temperature2008.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/europe/sweden/tornetrask-temperature2008.xls Grudd, H. 2008. Torneträsk tree-ring width and density AD 500-2004: a test of climatic sensitivity and a new 1500-year reconstruction of north Fennoscandian summers. Climate Dynamics, Vol. 31, pp. 843-857. DOI:10.1007/s00382-007-0358-2 START YEAR: 500 AD * END YEAR: 2004 AD 19.45 68.21 19.8 68.31