Trends and uncertainties in Siberian indicators of 20th century warming Export

@article{citeulike:5899125, abstract = {Estimates of past climate and future forest biomass dynamics are constrained by uncertainties in the relationships between growth and climatic variability and uncertainties in the instrumental data themselves. Of particular interest in this regard is the boreal-forest zone, where radial growth has historically been closely connected with temperature variability, but various lines of evidence have indicated a decoupling since about the 1960s. We here address this growth-vs.-temperature divergence by analyzing tree-ring width and density data from across Siberia, and comparing 20th century proxy trends with those derived from instrumental stations. We test the influence of approaches considered in the recent literature on the divergence phenomenon (DP), including effects of tree-ring standardization and calibration period, and explore instrumental uncertainties by employing both adjusted and nonadjusted temperature data to assess growth-climate agreement. Results indicate that common methodological and data usage decisions alter 20th century growth and temperature trends in a way that can easily explain the post-1960 DP. We show that (i) Siberian station temperature adjustments were up to 1.3 °C for decadal means before 1940, (ii) tree-ring detrending effects in the order of 0.620130.8 °C, and (iii) calibration uncertainties up to about 0.4 °C over the past 110 years. Despite these large uncertainties, instrumental and tree growth estimates for the entire 20th century warming interval match each other, to a degree previously not recognized, when care is taken to preserve long-term trends in the tree-ring data. We further show that careful examination of early temperature data and calibration of proxy timeseries over the full period of overlap with instrumental data are both necessary to properly estimate 20th century long-term changes and to avoid erroneous detection of post-1960 divergence.}, address = {Swiss Federal Research Institute WSL, Zrcherstrasse 111, 8903 Birmensdorf, Switzerland; Oeschger Centre for Climate Change Research, Erlachstrasse 9a, 3012 Bern, Switzerland; Laboratory of Dendrochronology, Institute of Plant and Animal Ecology, Ural Branch of Russian Academy of Sciences, 8 Marta Street, 222, Ekaterinburg 620144, Russia; V. N. Sukachev Institute of Forest SB RAS, 660036 Krasnoyarsk, Akademgorodok, Russia}, author = {Jan Espe, R. and David Fran, K. and Ulf B\"{u}ntge, N. and Anne Versteg, E. and Hantemirov, Rashit M. and Kirdyanov, Alexander V.}, citeulike-article-id = {5899125}, citeulike-linkout-0 = {http://dx.doi.org/10.1111/j.1365-2486.2009.01913.x}, citeulike-linkout-1 = {http://www3.interscience.wiley.com/cgi-bin/abstract/122374111/ABSTRACT}, doi = {10.1111/j.1365-2486.2009.01913.x}, issn = {1365-2486}, journal = {Global Change Biology}, keywords = {bias, boreal, climate, divergence, paleoclimate, proxy, temperature, tree-ring, trend, uncertainty}, number = {1}, pages = {386--398}, posted-at = {2009-10-06 15:54:12}, priority = {2}, title = {Trends and uncertainties in Siberian indicators of 20th century warming}, url = {http://dx.doi.org/10.1111/j.1365-2486.2009.01913.x}, volume = {16}, year = {2010} }

TY - JOUR ID - citeulike:5899125 L3 - citeulike-article-id:5899125 N2 - Estimates of past climate and future forest biomass dynamics are constrained by uncertainties in the relationships between growth and climatic variability and uncertainties in the instrumental data themselves. Of particular interest in this regard is the boreal-forest zone, where radial growth has historically been closely connected with temperature variability, but various lines of evidence have indicated a decoupling since about the 1960s. We here address this growth-vs.-temperature divergence by analyzing tree-ring width and density data from across Siberia, and comparing 20th century proxy trends with those derived from instrumental stations. We test the influence of approaches considered in the recent literature on the divergence phenomenon (DP), including effects of tree-ring standardization and calibration period, and explore instrumental uncertainties by employing both adjusted and nonadjusted temperature data to assess growth-climate agreement. Results indicate that common methodological and data usage decisions alter 20th century growth and temperature trends in a way that can easily explain the post-1960 DP. We show that (i) Siberian station temperature adjustments were up to 1.3 °C for decadal means before 1940, (ii) tree-ring detrending effects in the order of 0.620130.8 °C, and (iii) calibration uncertainties up to about 0.4 °C over the past 110 years. Despite these large uncertainties, instrumental and tree growth estimates for the entire 20th century warming interval match each other, to a degree previously not recognized, when care is taken to preserve long-term trends in the tree-ring data. We further show that careful examination of early temperature data and calibration of proxy timeseries over the full period of overlap with instrumental data are both necessary to properly estimate 20th century long-term changes and to avoid erroneous detection of post-1960 divergence. IS - 1 JF - Global Change Biology SN - 1365-2486 AD - Swiss Federal Research Institute WSL, Zrcherstrasse 111, 8903 Birmensdorf, Switzerland; Oeschger Centre for Climate Change Research, Erlachstrasse 9a, 3012 Bern, Switzerland; Laboratory of Dendrochronology, Institute of Plant and Animal Ecology, Ural Branch of Russian Academy of Sciences, 8 Marta Street, 222, Ekaterinburg 620144, Russia; V. N. Sukachev Institute of Forest SB RAS, 660036 Krasnoyarsk, Akademgorodok, Russia EP - 398 TI - Trends and uncertainties in Siberian indicators of 20th century warming VL - 16 SP - 386 KW - bias KW - boreal KW - climate KW - divergence KW - paleoclimate KW - proxy KW - temperature KW - tree-ring KW - trend KW - uncertainty AU - Jan Espe, R AU - David Fran, K AU - Ulf Büntge, N AU - Anne Versteg, E AU - Hantemirov, Rashit AU - Kirdyanov, Alexander PY - 2010/// UR - http://dx.doi.org/10.1111/j.1365-2486.2009.01913.x ER -