Move astronomy out of the atmosphere — that is where it belongs anyway, in orbit or on the far side of the moon.

The big question with such an all encompassing climate machine is “who will control it?”

You could easily turn any country you don’t like into a big popsicle. Shift the radiative balance just a little bit, and you control the ice ages of the future. Put them exactly where you want them. Or turn “lights out” for as long as you need to de-populate an entire region or continent. No need to burn the area and destroy all life in broad daylight. Let the entirety freeze in the darkness while the rest of the world goes about its business.

If you design an ultra-intelligent machine, you could just turn control of the climate machine over to the machine.

Otherwise assume the device will be used as an instrument of “politics by other means”. In other words, what are some variations that would accomplish the valuable ends you wish, without posing such a threat as one might fear?