Wood Anatomical Data from White Spruce (1950 -1999); Twisted Tree Heartrot Hill (TTHH); Yukon, Canada

Despite a lack of cold extremes during the current warm period (~1850 CE - present), records from tree rings in northwestern North America indicate that the summer of 1959 was uniquely cold relative to the last several centuries. In this study, we assessed the specific timing, magnitude, and spatial signature of this cold event using climate reanalysis data, a network of existing tree-ring records, and newly-developed wood anatomical data. Thin sections were produced from white spruce trees that were sampled in Yukon, Canada in the year 2000, and wood anatomical properties were analyzed using the software ROXAS (data herein). We found a particularly reduced cell wall thickness in the outer sector of the 1959 ring relative to other years, indicating that a major cold event happened in the late summer of 1959. Climate reanalysis data indicates a significant yet brief cold period spanning late July to early August likely contributed to an early cessation of cell wall thickening in that year. These results have important implications for the climatic interpretation of regional wood anatomical records.
Please refer to Leland et al. (2025) for additional details: Leland, C., Davi, N., D’Arrigo, R., Andreu-Hayles, L., Pacheco-Solana, A., Edwards, J., Anchukaitis, K.J., Porter, T.J., Pisaric, M.F., Mant, M. and Galloway, T., 2025. Tree-ring evidence of the elusive 1959 summer cold event in northwestern North America. Arctic, Antarctic, and Alpine Research, 57(1), p.2445945.