how about a large laser array powered by nuclear power heating large areas of the caps and use a large magnifying glass type lens to intensify the beams. Hell a nuclear power plant using the cold of the planet to cool it allowing the heat to heat the surrounding area and also producing electricity for any colony also. SO many ways this could be done, hell take a few asteroid and allow them to impact the area and they'll be hot coming in, just not huge ones that'll leave dust in the atmosphere.