Summer temperature variability since 1730 CE across the low-to-mid latitudes of western North America from a tree ring blue intensity network

Regional reconstructions of air temperature over the past millennium provide critical context for ongoing climate change, but they are temporally limited in recent period or absent many parts world. We demonstrate use latewood blue intensity (LWB) to reconstruct current-year growing (warm) season maximum temperatures (Tmax) low-to-mid latitudes (30°-50°N) western North America. present a new tree ring network comprised 26 LWB chronologies developed from living, high-elevation Engelmann spruce (Picea engelmannii Parry ex Engelm.) sampled across United States. The parameter shows strong, positive (r = 0.65–0.73), and temporally-stable correlations with Tmax. From this we 4 regional Tmax reconstructions, which characterize histories America northern Mexico southern British Columbia centuries. Our comparison these highlights spatial patterns trends throughout time. These important updates increased data point density proxy Northern Hemisphere. highlight methods at both low- mid-latitude upper line locations increase presence strongly temperature-sensitive records increasingly lower