Not really. If the issue was thermometers getting more accurate, other proxy methods would show a similar divergence. Trees are complex organisms whose growth

Not really. If the issue was thermometers getting more accurate, other proxy methods would show a similar divergence. Trees are complex organisms whose growth relies on many factors in a complicated relationship. Just as a simple example, if you have a long, hot drought, do you expect tree growth to be more affected by the temperature or the lack of moisture? The scientists must control for these kinds of factors to isolate the temperature signal. But when you're dealing with the interactions of complex systems, new factors can emerge and the methods need to change to keep up.