DOI: 10.25921/87vs-2p80
title: NOAA/WDS Paleoclimatology - Pyrenees, 1260-2006 AD, Maximum Latewood Density, tree ring width, Mountain Pine, PAGES Euro-Med 2k Version

description: Past temperature variations are usually inferred from proxy data or estimated using general circulation models. Comparisons between climate estimations derived from
       proxy records and from model simulations help to better understand mechanisms driving climate variations, and also offer the possibility to identify deficiencies in both approaches.
       This paper presents regional temperature reconstructions based on tree-ring maximum density series in the Pyrenees, and compares them with the output of global simulations for
       this region and with regional climate model simulations conducted for the target region. An ensemble of 24 reconstructions of May-to-September regional mean temperature was
       derived from 22 maximum density tree-ring site chronologies distributed over the larger Pyrenees area. Four different tree-ring series standardization procedures were applied,
       combining two detrending methods: 300-yr spline and the regional curve standardization (RCS). Additionally, different methodological variants for the regional chronology were
       generated by using three different aggregation methods. Calibration verification trials were performed in split periods and using two methods: regression and a simple variance matching.
       The resulting set of temperature reconstructions was compared with climate simulations performed with global (ECHO-G) and regional (MM5) climate models. The 24 variants of May-to-September temperature reconstructions
       reveal a generally coherent pattern of inter-annual to multi-centennial temperature variations in the Pyrenees region for the last 750 yr. However, some reconstructions display
       a marked positive trend for the entire length of the reconstruction, pointing out that the application of the RCS method to a suboptimal set of samples may lead to unreliable results.
       Climate model simulations agree with the tree-ring based reconstructions at multi-decadal time scales, suggesting solar variability and volcanism as the main factors controlling
       preindustrial mean temperature variations in the Pyrenees. Nevertheless, the comparison also highlights differences with the reconstructions, mainly in the amplitude of
       past temperature variations and in the 20th century trends. Neither proxy-based reconstructions nor model simulations are able to perfectly track the temperature variations of the
       instrumental record, suggesting that both approximations still need further improvements.
description: A dataset of 804 individual maximum density (MXD) treering series, grouped into 22 chronologies covering the Pyrenees area, was available for the present study. The network includes the two chronologies previously used to develop the first tree-ring based regional reconstruction of past maximum temperatures in the Pyrenees (Büntgen et al., 2008): additional data published in Büntgen et al. (2010), and a newly developed 700-yr long MXD chronology. Compared to the previous reconstruction of maximum temperature, the new dataset covers a wider area and uses a larger replication, not only in most recent centuries, but also in the earliest part of the period (1260-1350 AD). The location, elevation and tree species at each site are indicated in Fig. 1. The species sampled were Mountain pine (Pinus uncinata Ramond ex DC. in Lam. et DC.), a shade-intolerant and long-lived conifer that grows under temperate subalpine climate conditions and dominates at elevations above 1800m a.s.l., and Silver fir (Abies alba Mill.) that usually grows at humid sites on north facing, shady slopes and at elevations above 1200m a .s.l. (Macias et al., 2006). Scientific name "Pinus mugo Turra = Pinus montana Mill." used as a synonym for the species "Pinus uncinata Ramond ex DC".