Large-scale, millennial-length temperature reconstructions from tree-rings

Jan Esper, Scott St George, Kevin Anchukaitis, Rosanne D'Arrigo, Fredrik Charpentier Ljungqvist, Jürg Luterbacher, Lea Schneider, Markus Stoffel, Rob Wilson, Ulf Büntgen

Research output: Contribution to journalReview articlepeer-review

35 Scopus citations

Abstract

Over the past two decades, the dendroclimate community has produced various annually resolved, warm season temperature reconstructions for the extratropical Northern Hemisphere. Here we compare these tree-ring based reconstructions back to 831 CE and present a set of basic metrics to provide guidance for non-specialists on their interpretation and use. We specifically draw attention to (i) the imbalance between (numerous) short and (few) long site chronologies incorporated into the hemispheric means, (ii) the beneficial effects of including maximum latewood density chronologies in the recently published reconstructions, (iii) a decrease in reconstruction covariance prior to 1400 CE, and (iv) the varying amplitudes and trends of reconstructed temperatures over the past 1100 years. Whereas the reconstructions agree on several important features, such as warmth during medieval times and cooler temperatures in the 17th and 19th centuries, they still exhibit substantial differences during 13th and 14th centuries. We caution users who might consider combining the reconstructions through simple averaging that all reconstructions share some of the same underlying tree-ring data, and provide four recommendations to guide future efforts to better understand past millennium temperature variability.

Original languageEnglish (US)
Pages (from-to)81-90
Number of pages10
JournalDendrochronologia
Volume50
DOIs
StatePublished - Aug 2018

Bibliographical note

Funding Information:
We are grateful to Keith Briffa for his pioneering work on large-scale temperature reconstructions. Supported by the German Science Foundation , grants # Inst 247/665-1 FUGG and ES 161/9-1 . SSG acknowledges support by the Alexander von Humboldt Foundation, KJA by the US National Science Foundation grants AGS-1501856 and NSF AGS-1501834 , and JL and LS by the Belmont Forum and JPI-Climate, Collaborative Research Action INTEGRATE . A data file (NH-reconstructions.xlsx) containing the six annually resolved millennial-length reconstructions, scaled over 1881–1992 to June-August 30–70 °N land temperatures, is available at: https://www.blogs.uni-mainz.de/fb09climatology/publications-jan-esper-2/

Funding Information:
We are grateful to Keith Briffa for his pioneering work on large-scale temperature reconstructions. Supported by the German Science Foundation, grants # Inst 247/665-1 FUGG and ES 161/9-1. SSG acknowledges support by the Alexander von Humboldt Foundation, KJA by the US National Science Foundation grants AGS-1501856 and NSF AGS-1501834, and JL and LS by the Belmont Forum and JPI-Climate, Collaborative Research Action INTEGRATE. A data file (NH-reconstructions.xlsx) containing the six annually resolved millennial-length reconstructions, scaled over 1881–1992 to June-August 30–70 °N land temperatures, is available at: https://www.blogs.uni-mainz.de/fb09climatology/publications-jan-esper-2/

Publisher Copyright:
© 2018 Elsevier GmbH

Keywords

  • Little Ice Age
  • Maximum latewood density
  • Medieval Warm Period
  • Northern Hemisphere
  • Tree-ring width
  • Warm season temperatures

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