Living in climates where there is snow and temperatures get below freezing, it is important to prevent ice dams from forming on your gutters and roof. These usually occur after heavy snowfall followed by really cold temperatures. Ice dams that build up can cause serious damage including destroying gutters and eaves, causing water leaks in the exterior walls or attic, reducing the effectiveness of insulation and creating mold and mildew problems. It is important to be diligent and prevent them from occurring, but you also have to be safe when attempting to solve the problem. Sometimes it may be better to call for a professional to help.
This is a dangerous job as it requires climbing onto your roof in the winter time, so many people will hire a professional company to do this. The main piece of equipment to do this a steamer, which is a like a pressure washer but will heat the water.
You use the steamer to cut chunks of ice off and in order to break up the large mass of ice, and get the ice off the roof and the gutter.
Here is a great sample video from oscarkuhl.