Changes to the Earth's orbit drove centuries of cooling, but temperatures rose fast in the last 100 years as human greenhouse gas emissions rose.
Scientists took evidence from ice cores, tree rings and lake sediments.
Writing in the journal Science, they say this confirms that the Arctic is very sensitive both to changes in solar heating and to greenhouse warming.
The 23 sites sampled were good enough to provide a decade-by-decade picture of temperatures across the region.
The result is a "hockey stick"-like curve in which the last decade - 1998-2008 - stands out as the warmest in the entire series.
