Last millennium Northern Hemisphere summer temperatures from tree rings: Part II, spatially resolved reconstructions. (1st May 2017)

• Record Type: Journal Article
• Authors: Anchukaitis, Kevin J.; Wilson, Rob; Briffa, Keith R.; Büntgen, Ulf; Cook, Edward R.; D'Arrigo, Rosanne; Davi, Nicole; Esper, Jan; Frank, David; Gunnarson, Björn E.; Hegerl, Gabi; Helama, Samuli; Klesse, Stefan; Krusic, Paul J.; Linderholm, Hans W.; Myglan, Vladimir; Osborn, Timothy J.; Zhang, Peng; Rydval, Milos; Schneider, Lea; Schurer, Andrew; Wiles, Greg; Zorita, Eduardo
• Is Part Of: Quaternary science reviews. Volume 163(2017)
• Page Start: 1
• Page End: 22
• Publication Date: 2017-05-01
• Subjects: Tree-rings -- Northern Hemisphere -- Last millennium -- Common Era -- Summer temperatures -- Reconstruction -- Spatial; Geology, Stratigraphic -- Quaternary -- Periodicals; Stratigraphie -- Quaternaire -- Périodiques; 551.79
• DOI: 10.1016/j.quascirev.2017.02.020
• Languages: English
• ISSNs: 0277-3791

Abstract

Abstract: Climate field reconstructions from networks of tree-ring proxy data can be used to characterize regional-scale climate changes, reveal spatial anomaly patterns associated with atmospheric circulation changes, radiative forcing, and large-scale modes of ocean-atmosphere variability, and provide spatiotemporal targets for climate model comparison and evaluation. Here we use a multiproxy network of tree-ring chronologies to reconstruct spatially resolved warm season (May–August) mean temperatures across the extratropical Northern Hemisphere (40-90°N) using Point-by-Point Regression (PPR). The resulting annual maps of temperature anomalies (750–1988 CE) reveal a consistent imprint of volcanism, with 96% of reconstructed grid points experiencing colder conditions following eruptions. Solar influences are detected at the bicentennial (de Vries) frequency, although at other time scales the influence of insolation variability is weak. Approximately 90% of reconstructed grid points show warmer temperatures during the Medieval Climate Anomaly when compared to the Little Ice Age, although the magnitude varies spatially across the hemisphere. Estimates of field reconstruction skill through time and over space can guide future temporal extension and spatial expansion of the proxy network. Highlights: The Northern Hemisphere temperature field is reconstructed using tree-ring proxies. Point-by-Point Regression is used at the hemisphere-scale for the first time. Widespread warmth is detected during the Medieval Epoch. Coherent large-scale cooling follows large volcanic eruptions. Spatial analysis can guide future collection, updating, and network expansion.