The global tree-ring community is racking up the papers investigating the utility of the relatively new proxy using blue intensity of annually-dated tree rings. This latest effort is a blue intensity investigation followup of a recent study on ring widths also led by Dr. Santosh Shah of Birbal Sahni Institute of Palaeosciences in Locknow, India. Blue intensity is a proxy that has added a new dimension to thermal histories across the globe including efforts at the The College of Wooster Tree Ring Lab. Shah et al. (2025) used cores extracted from three sites of the Western Himalayan Fir (Abies pindrow) from the Kashmir Valley.
Map from the study showing the location of the three tree-ring sites and the meteorological station (Srinager). The centrally-located Srinager climate station has records of precipitation and temperature spanning 1901-2024, one of the longest in the region.
A figure from the paper showing the beautiful images of earlywood (above) and latewood (below) blue light reflectance for individual rings from the Western Himalayan Fir (Abies pindrow).
The upshot of the work is that time series of blue intensity values from the latewood of A.Pindrow are strongly correlated with monthly average and maximum temperature series from nearby climate station (Srinager). Ring-width are