High-Resolution Temperature Variability Reconstructed from Black Pine Tree Ring Densities in Southern Spain

The presence of an ancient, high-elevation pine forest in the Natural Park of Sierras de Cazorla in southern Spain, including some trees reaching >700 years, stimulated efforts to develop high-resolution temperature reconstructions in an otherwise drought-dominated region. Here, we present a reconstruction of spring and fall temperature variability derived from black pine tree ring maximum densities reaching back to 1350 Coefficient of Efficiency (CE). The reconstruction is accompanied by large uncertainties resulting from low interseries correlations among the single trees and a limited number of reliable instrumental stations in the study region. The reconstructed temperature history reveals warm conditions during the early 16th and 19th centuries that were of similar magnitude to the warm temperatures recorded since the late 20th century. A sharp transition from cold conditions in the late 18th century (t(1781-1810)= -1.15 degrees C +/- 0.64 degrees C) to warm conditions in the early 19th century (t(1818-1847)= -0.06 degrees C +/- 0.49 degrees C) is centered around the 1815 Tambora eruption (t(1816)= -2.1 degrees C +/- 0.55 degrees C). The new reconstruction from southern Spain correlates significantly with high-resolution temperature histories from the Pyrenees located similar to 600 km north of the Cazorla Natural Park, an association that is temporally stable over the past 650 years (r(1350-2005)> 0.3,p< 0.0001) and particularly strong in the high-frequency domain (r(HF)> 0.4). Yet, only a few of the reconstructed cold extremes (1453, 1601, 1816) coincide with large volcanic eruptions, suggesting that the severe cooling events in southern Spain are controlled by internal dynamics rather than external (volcanic) forcing.