It all depends on your momentum.
A simple example - You are approaching at 100 Knots airspeed into a 10 knot headwind with power / thrust set for steady flight, so, your groundspeed is 90 knots. Your aerodynamic performance depends on your airspeed (100 Kt), your momentum depends upon your Groundspeed (90 Kt).
Suddenly you encounter a headwind of 20 knots, your airspeed is suddenly 110 Kt because your aircraft remains at 90 Kt groundspeed due to it's momentum, and the 20 Kt headwind gives you 110 Kt airspeed. You have increasing lift, i.e. overshoot shear.
If the aircraft is left alone, after a short time, the airspeed will stabilise at 100 Kt again with a new Groundspeed of 80 Kt because the increased drag at 100 Kt will return the aircraft to the speed for which power / thrust was applied, i.e. 100 Kt.
The same applies for decreasing tailwind, the opposite applies for increasing tailwind / decreasing headwind.