The tree rings used for temperature are from trees at
quite high latitudes, where temperature has historically been the limiting factor.
Not exact matches
Furthermore, the relatively
high «sensitivity» from glacial to interglacial is largely driven by the change in the orbit relative to the Sun, which changes the distribution of incident solar energy into the system
quite dramatically (more energy is distributed to the
higher latitudes in the NH summer, in particular).
Given how global warming from CO2 is delivered prefentially over land,
high latitudes, in the winter 1.1 C should be
quite welcome even before considering that plants will grow faster using less water and have a longer growing season in which to do it.
As a slight variant on this, some deciduous trees that grow at
high latitudes are not
quite so dark and have bigger water fluxes.