A 7400-year tree-ring chronology in northern Swedish Lapland: natural climatic variability expressed on annual to millennial timescales

Abstract

Tree-ring widths from 880 living, dry dead, and subfossil northern Swedish pines (Pinus syl vestris L.) have been assembled into a continuous and precisely dated chronology (the Torneträsk chronology) covering the period 5407 BC to ad 1997. Biological trends in the data were removed with autoregressive standardization (ARS) to emphasize year-to-year variability, and with regional curve stan dardization (RCS) to emphasize variability on timescales from decades to centuries. The strong association with summer mean temperature (June–August) has enabled the production of a temperature reconstruction for the last 7400 years, providing information on natural summer-temperature variability on timescales from years to centuries. Numerous cold episodes, comparable in severity and duration to the severe summers of the seventeenth century, are shown throughout the last seven millennia. Particularly severe conditions suggested between 600 and 1 BC correspond to a known period of glacier expansion. The relatively warm conditions of the late twentieth century do not exceed those reconstructed for several earlier time intervals, although replication is relatively poor and confidence in the reconstructions is correspondingly reduced in the pre-Christian period, particularly around 3000, 1600 and 330 bc. Despite the use of the RCS approach in chronology construction, the 7400-year chronology does not express the full range of millennial-timescale temperature change in northern Sweden.

Climatic factors affecting the tree‐ring width of Betula ermanii at the timberline on Mount Norikura, central Japan

“…Although most dendrochronological and/or dendroclimatological studies have not examined the effects of insolation duration on the tree-ring width, many researchers reported that tree growth was limited by low summer temperatures in high altitudes and high latitudes (Oberhuber et al 1997;MacDonald et al 1998;Gervais & MacDonald 2000;Mäkinen et al 2000;Grudd et al 2002;Helama et al 2002;Kirdyanov et al 2003;Takahashi 2003a;Barber et al 2004;Takahashi 2005Takahashi , 2006. Low temperatures reduce the tree growth through several ways.…”

Fingerprints of extreme climate events in Pinus sylvestris tree rings from Bulgaria

“…Scots pine (Pinus sylvestris L.) is one of these species and is wide spread world-wide and in specific regions (Richardson 2000). In addition to this, numerous studies are available on P. sylvestris tree-ring width, density and anatomy variation and their dependence on climate (Grudd et al 2002;Briffa et al 2004;Antonova et al 1995;Rigling et al 2001;Eilmann et al 2006;Büntgen et al 2010;Oberhuber and Gruber 2010;Gruber et al 2010;Eilmann et al 2011). Yet, these studies were generally focused on specific sites or factors and thus, do not provide sufficient evidence of how tree-ring features could be indicative of different extremes dependent on the location.…”

On past temperatures and anomalous late‐20th‐century warmth

“…All series are shown with respect to the 1961-90 base period. [Mann et al, 1999]; "Chesapeake Bay" [Cronin et al, 2003]; "W. Greenland" [Fisher et al, 1996]; "Tornetrask" [Grudd et al, 2002]; "Low Countries" [van Engelen et al, 2001); "Yamal" [Hantemirov andShiyatov, 2002, reprocessed in Briffa, 2000]; "Taimyr" [Naurzbaev et al, 2002]; "Mongolia" [D'Arrigo et al, 2001]; "China" [Yang et al, 2002].…”