After settling on the island, the settlers started deforestation, which resulted in a complete removal of trees. How did they stay warm during winter before they had the technology to use the geothermal resources found there?
They used seaweed oddly enough. While most deforested areas used peat for there fuel needs Iceland, being an island, used a more common fuel. One that could be found on every shore line. Source http://www.noamkelp.com/technical/iceland.html