Wind, solar, and run of river hydro are unscheduled so if load ramps up due to renewable generation ramping up there is no change in load to be accommodated by dispatchable scheduled units.

If the load responding to increased renewable generation exceeded the generation then the excess load should have just run whenever it was convenient since it isn’t using renewable power anyway.

I’ve omitted nuclear and large hydro from my discussion even though their fuel doesn’t emit carbon.