Wind turbines extract kinetic energy from the air around them, and since less energy makes for weaker winds, turbines do indeed make it less windy. Technically speaking, the climate zone right behind a turbine (or behind all the turbines on a wind farm) experiences what’s called a “wind speed vacuum,” or a “momentum deficit.” In other words, the air slows down.
The effect has implications for wind-farm efficiency. Upwind turbines in a densely packed farm may weaken the breeze before it reaches the downwind ones. It could even have a more general impact. If wind farms were constructed on a truly massive scale, their cumulative momentum deficit could conceivably alter wind speeds on a global scale
The same geniuses who worry about miniscule effects related to CO2, have no problem with causing major changes to global wind patterns.