Trends and uncertainties in Siberian indicators of 20th century warming

Jan Esper, David Frank, Ulf Büntgen, Anne Verstege, Rashitm Hantemirov, Alexander V. Kirdyanov

Research output: Contribution to journalArticlepeer-review

90 Scopus citations


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 borealforest 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 0.6-0.8 °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 longterm changes and to avoid erroneous detection of post-1960 divergence.

Original languageEnglish (US)
Pages (from-to)386-398
Number of pages13
JournalGlobal change biology
Issue number1
StatePublished - Jan 2010
Externally publishedYes


  • Boreal forest
  • Climate data
  • Proxy data
  • Siberia
  • Tree-rings
  • Wood density

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Ecology
  • Environmental Science(all)


Dive into the research topics of 'Trends and uncertainties in Siberian indicators of 20th century warming'. Together they form a unique fingerprint.

Cite this