Very good, detailed article in the New Yorker by Elizabeth Kolbert about Samsø, an island in Denmark, which has gone to zero, in ten years, in its CO2 production.
quite deliberately, the residents of the island set about changing [their oil consumption. They formed energy coöperatives and organized seminars on wind power. They removed their furnaces and replaced them with heat pumps. By 2001, fossil-fuel use on Samsø had been cut in half. By 2003, instead of importing electricity, the island was exporting it, and by 2005 it was producing from renewable sources more energy than it was using.