Starting small doesn't work if you have a nonlinear system. In nonlinear systems, the magnitude of a perturbance isn't linearly related to the absorbed effect.
So in the worst case: small input, giant irreversible effect.
So in the worst case: small input, giant irreversible effect.
Of course that’s impossible to do since the world itself is doing things like erupting volcanos, shifting plates, melting glaciers, and redirecting ocean currents.