Revising midlatitude summer temperatures back to A.D.600 based on a wood density network

• Published in: Geophysical research letters Vol. 42; no. 11; pp. 4556 - 4562
• Main Authors: Schneider, Lea, Smerdon, Jason E, Buentgen, Ulf, Wilson, Rob JS, Myglan, Vladimir S, Kirdyanov, Alexander V, Esper, Jan
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 01-06-2015
• Subjects: Age; Annual variations; Bias; Chronology; Cooling; Density; Ice; Ice ages; Little Ice Age; Networks; Northern Hemisphere; Reconstruction; Records; Recovery; Seasonal variations; Summer; Summer temperatures; Temperature; Temperature effects; Temperature variability; Trends; Variability; Volcanic eruptions; Width; Wood; Northern Hemisphere
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2015GL063956

Annually resolved and millennium-long reconstructions of large-scale temperature variability are primarily composed of tree ring width (TRW) chronologies. Changes in ring width, however, have recently been shown to bias the ratio between low- and high-frequency signals. To overcome limitations in capturing the full spectrum of past temperature variability, we present a network of 15 maximum latewood density (MXD) chronologies distributed across the Northern Hemisphere extratropics. Independent subsets of continental-scale records consistently reveal high MXD before 1580 and after 1910, with below average values between these periods. Reconstructed extratropical summer temperatures reflect not only these long-term trends but also distinct cooling pulses after large volcanic eruptions. In contrast to TRW-dominated reconstructions, this MXD-based record indicates a delayed onset of the Little Ice Age by almost two centuries. The reduced memory inherent in MXD is likely responsible for the rapid recovery from volcanic-induced cooling in the fourteenth century and the continuation of warmer temperatures until ~1600. Key Points * First millennial climate reconstruction based on extratropical tree ring density network * Improved ratio between low- and high-frequency temperature variability * New insights into postvolcanic cooling and the onset of the Little Ice Age