Can you please try to control the weather first? Because we know from observation that that's just molecules pushing each other around, and it's a lot less complicated then life, so it should be easier to control, right? (only -- intractability)
No, it's actually more complicated. Biological machinery doesn't push molecules at random. Sure it's a lot to work out, but we've been doing it for the last 100 years with a lot of success. Google up some things we can make bacteria do nowdays.
By the way, the primary obstacle to controlling the weather is not the molecular-level interactions, it's the power requirements. Given enough energy generation, we could control weather using today's technology, just as we can do indoors with air conditioning and various experiments like "hey, let's make a cloud indoors and make it rain". Hell, your friendly neighbourhood nuclear power plant produces clouds and rain as a part of its daily operations. We just don't have enough raw power to do it on planetary scale (and we'd probably screw ourselves over big time if we had), as this article [0] kindly explains.
There's no intractability here, with enough power you could just push the air around any way you like. Weather is transforming energy in a very, very complex set of feedback loops, but you could override it completely with even more energy. You can throw paper balls at a cat to try and get it to move somewhere, or you can just grab it and put it where you want it to be (and then catch it again, because it will most definitely try to escape).
> with enough power you could just push the air around any way you like
Maybe a real god could, but we can't. Unless you have tractor beams, anti-gravity force fields and other sci-fi tech, either you'd have to have these "weather machines" placed in a fairly tight grid, or intractability would rule (outside a small area of influence). The problem isn't just energy, but directing it.
Also, the inefficiency of ex: wind turbines would add a lot of energy which would be counter productive. You might be able to control the weather by blocking out the sun and then selectively lighting some areas over others. But that's not really controlling weather so much as setting the temperature on an AC.
