If the climate becomes unreliable you need large scale underground water storage of rain to compensate this.

Basically you need cheap, replaceable solar-pumps (that one is allready doable).

And you need cheap, near surface volumes dug out and sealed. Actually all you need for that is - a water pump and a glorified fridge. You drill a initial hole- and now you pump water in and freeze it. Water expands, you thaw it and repeat. Basically a giant intentional pothole.

Now, anyone here into tunnel engineering? How to cheaply seal the resulting artificial cavern?