Tree-ring evidence of the elusive 1959 summer cold event in northwestern North America

Tree-ring records in northwestern North America suggest that the year 1959 was anomalously cold relative to the last several centuries. Here, we investigate the spatial characteristics, specific timing, and magnitude of the 1959 cold event through analyzing a multiparameter tree-ring network, including two wood anatomical records, and climate reanalysis data. By assessing the sensitivity of tree-ring data to a climate extreme during the instrumental era, we can better understand the capacity of these records to capture historical climate extremes. Our results suggest that cool conditions prevailed across the region in the summer of 1959, but the most extreme cold was centered around northwestern Canada, where maximum latewood density and cell wall thickness anomalies were exceedingly low. Though the entire summer of 1959 was cool, a brief episode of record cold temperatures from late July through early August likely contributed greatly to the extreme tree-ring anomalies. Our findings highlight that climate extremes during critical periods of the growing season can leave a significant imprint on maximum latewood density and that high-resolution wood anatomical data can be particularly powerful for identifying and potentially reconstructing the timing, duration, and magnitude of historical and undocumented climate extremes.