So much for tree rings as a temperature proxy.
Huge Canadian Tree Growth Study.
Our analyses of a new methodologically standardized tree-ring dataset covering Canada’s boreal forest provide insights into the growth responses of this ecosystem to climate change. Although revealing no overarching “growth enhancement” or “growth decline” in recent years, results do point to significant regional- and species-related trends in growth. The observed link between climate variation and growth variability revealed unique evidence of an intensification of the impacts of hydroclimatic variability on growth late in the 20th century, in parallel with the rapid rise of summer temperature.
Such response can be attributed to annual growth variability in these forests being mainly driven by negative sensitivity to summer temperature (warmer summers leading to less growth) and positive sensitivity to summer soil moisture (more moisture leading to more growth)