I think in the big picture the effects you are talking about are really small in the same way that the heat dissipation of all our energy use (from whatever ene

I think in the big picture the effects you are talking about are really small in the same way that the heat dissipation of all our energy use (from whatever energy sources) is negligible relative to daily incoming/outgoing solar radiation. Greenhouse gases affect these much larger energy flows (which is our problem right now), but the energy "produced" or "used" (i.e. transformed into entropy) by civilization barely even registers on that scale, and that's what you're talking about when you say "energy extracted from the weather system". Of course if we keep doubling the size of our economy (and thus energy use) every 25 years, then we will start having to worry about the heat dissipated by it all in a couple of hundred years even if all of it comes from perfectly green fusion reactors!