The Martian moons Phobos and Deimos are made up of some of the darkest material in the Solar System. If a solar powered mass driver were placed on Phobos it could be mined for the dark material and used as a kind of rocket fuel by the recoil of the mass driver hurling mined slugs of the material into and over the Martian Polar Ice Caps.
This would also change the orbit while also lowering its mass, and eventually place it in a Polar orbit. Larger chunks could then be deployed to continue to cover the Polar caps with Dark Carbon like material which could absorb light and melt the polar caps.
The lowering of the mass of Phobos would make it more likely to break apart and easier to mine, close to the Roche limit it should be very easy to redirect huge portions into a controlled break up over the Martian polar caps to maximize coverage and heating effects.
As relics of the Frost belt and being in orbit about Mars when it lost most of its water there is also a good chance a significant portion of the material may contain water and could be salvaged for rocket fuel for orbital travel and deceleration of incoming spacecraft.
Deimos being in a higher orbit and smaller, could also be used as an Electromagnetic dynamo to create a sustained magnetic field. Powered by its orbital kinetic energy, by trailing a long dipole antenna from the moon a distance towards the planet.
This was proven in an experiment conducted on the space shuttle in Earth orbit. Scaled up.. it should provide some protection at certain atitudes for any travelers or bases in orbit.. as from a solar flare.. and on the surface at certain latitudes.