The climate flux would take thousands to millions of year to run its course before anthropogenic activity accelerating it by thousand-fold. In that case we could adapt easily since even evolution, as slow as it is, was capable of doing so without technology.
We know that things change, including the climate, the tectonic plates, etc., the issue is how fast things change, that's where catastrophe lies and the call is not to keep the climate as close as possible to the 1700s but to deal with the mess we created and slow down the process of change so not only humans but other species have the chance to adapt as well.