Effects of multiple wind farms: since the net result of one is zero, the net result of many will be zero.
The net result can't possibly be zero, energy is being extracted from the system. Now it may very well be that, as another poster suggested, the amount of energy being extracted is so small as to have no net measurable effect, and while that may be understood to the the case on a very small scale, I personally don't have a good intuitive feel for that when you scale up to many gigawatts. Extrapolating the effects from a very small wind farm to a massive one (on a global scale) would seem imprudent to me. I'm not completely ignorant in the matter, but neither have I researched it in enough depth to satisfy my curiosity. Your response of "it's zero, now go away troll!" doesn't help. Perhaps you have pointers to some research or even just some well-written articles from science journalists to back your opinion. Your personal intuition doesn't count any more than mine does.
I have similar questions about all-electric cars. Sure, an electric car emits effectively zero emissions when it's driving around, but the energy to move it around came from somewhere. Given our current power infrastructure, it's far from clear to me just how much better an electric car is from a fossil fuel car. My intuition is that it likely is measurably better, but I'd really like some science that backs that up. I think the larger benefit to electric cars is that any improvements made to power plant efficiency and cleanliness directly translates to less emissions attributable to the electric cars that are already on the road, but I'm nowhere near convinced that today's electric cars are significantly superior to the higher fuel efficiency internal combustion cars. That doesn't mean I'm an anti-electric car troll. It used to be that critical thinking and skepticism were valued, especially in scientific discussions, and not considered the hallmark of trolls and shills and subjected to automatic ridicule.
However, putting up sufficient wind power means we can reduce the use of other kinds of power which actually do have a negative effect on climate (from our POV.)
Certainly. And given the difficulty in deploying wind farms on a massive scale (on the ground or in the atmosphere), there will be plenty of time for scientists to measure and understand the possible effects of such scaled-up deployments. Despite the propensity of the anti-science religious right to use scientific skepticism as an argument against science in general, that's how science must always be conducted.
Rather than attacking as a troll someone for asking what was likely an innocent question based out of ignorance (not stupidity as you so arrogantly suggested), it might be more constructive to simply point out their ignorance and maybe even point them in the direction of some useful materials to educate themselves. Reflexively calling them a troll or stupid just eliminates any credibility you might have had, at least in my opinion.