First, the problem: spreading drought, possibly a result of growing climate change, possibly something occurring with increasing frequency. Whether or no, it's still ruining crops. Fewer crops, less food, higher prices, more hunger, more wars.
There's plenty of water in the world. That's not the issue. It's the distribution and the quality. It falls too much or too little in any place at any given time. The large reservoirs are polluted with things like salt which prevent its use in agriculture. Growing population increases demand for water, so the need even in ideal distribution years will not be going away.
(Thus speaks someone who's moving to Arizona for half the year.)
But right now I live in Minnesota, and even when there's not much on the ground, there's still plenty in the air. Step outside and try to breathe, if you doubt me. Put ice in your drink and watch the water dribble down the outside of the glass and ruin the wood finish on the table, if you're still not convinced.
So why don't we harvest it? Now I'm not talking cheap, here, or without effort, or resources, or technology. But most of the energy should be renewable, at least, and while the output may be slow, it's a way to provide water in the spots where roots can soak it up. How long before we're that desperate?
Here's the idea. Using geo-thermal cooling, install a system of underground pipes with liquid flowing through and coming back to the surface to circulate in something modeled on a radiator. It needs a lot of surface area per water-from-air output, but if it sits on the ground, the water will drip down to the root zones without re-evaporation. Power for circulation can be provided by either wind or solar energy. Maybe somebody can come up with a material that isn't metal but can transfer heat as well as metal. Perhaps a special glass, since that's what works in the home, and there's plenty of silica in the world.
This is obviously a simplified version of what's needed, but how about it, engineers? If anybody wants to take this idea and run with it, no credit necessary.
The rest of you, how about just no laughing please?