Also interesting to hear these findings agree with the documentary evidence.

Yes, we would love to see other groups try something similar. The Canadian group were planning to do this after we presented the concept to CMIP7.

I think 1750 would be ideal but starting in 1800 would include simulation of the major volcanic eruptions which is important for post-1850 climate. When we suggested these ideas for CMIP7 the modelling centres saw the value but were not keen on spending (limited) computational resources on this.

We performed parallel simulations using 1750 and 1850 frameworks.

When starting in 1750, the simulated climate for lengthy periods after 1850 is different from simulations started in 1850, even with the same radiative forcings.

This is mainly because of volcanoes & land use changes before 1850.