title: Causes and consequences of past and projected Scandinavian summer temperatures, 500-2100 AD.
abstract: Tree rings dominate millennium-long temperature reconstructions and many records originate from Scandinavia, an area for which the relative roles of external forcing and internal variation on climatic changes are, however, not yet fully understood. Here we compile 1,179 series of maximum latewood density measurements from 25 conifer sites in northern Scandinavia, establish a suite of 36 subset chronologies, and analyse their climate signal. A new reconstruction for the 1483-2006 period correlates at 0.80 with June-August temperatures back to 1860. Summer cooling during the early 17th century and peak warming in the 1930s translate into a decadal amplitude of 2.9°C, which agrees with existing Scandinavian tree-ring proxies. Climate model simulations reveal similar amounts of mid to low frequency variability, suggesting that internal ocean-atmosphere feedbacks likely influenced Scandinavian temperatures more than external forcing. Projected 21st century warming under the SRES A2 scenario would, however, exceed the reconstructed temperature envelope of the past 1,500 years.
authors.affiliation: Swiss Federal Research Institute WSL, Birmensdorf, Switzerland. buentgen@wsl.ch
authors.forename: Ulf
authors.initials: U
authors.lastname: Büntgen
authors.forename: Christoph C
authors.initials: CC
authors.lastname: Raible
authors.forename: David
authors.initials: D
authors.lastname: Frank
authors.forename: Samuli
authors.initials: S
authors.lastname: Helama
authors.forename: Laura
authors.initials: L
authors.lastname: Cunningham
authors.forename: Dominik
authors.initials: D
authors.lastname: Hofer
authors.forename: Daniel
authors.initials: D
authors.lastname: Nievergelt
authors.forename: Anne
authors.initials: A
authors.lastname: Verstege
authors.forename: Mauri
authors.initials: M
authors.lastname: Timonen
authors.forename: Nils Chr
authors.initials: NC
authors.lastname: Stenseth
authors.forename: Jan
authors.initials: J
authors.lastname: Esper
mesh_terms: D057231:Climate Change; D012537:Scandinavian and Nordic Countries; D012621:Seasons; D013696:Temperature