Actually, for northern climates it is a warmer roof that typically causes the snow to melt and re-freeze creating ice dam problems. Quite often this can be traced to poor insulation details or installation. A cool roof actually helps prevents the snow from thawing, and therefore prevents the ice dams.
That's exactly what I was saying. The warmer part melts the snow... it runs down on to the cooler part... refreezes and Voila.... ice dam
