The BBC has the summary:
Arctic temperatures are now higher than at any time in the last 2,000 years, research reveals.
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 full article is firewalled at Science, but it’s long enough to allow some significant quotes. The lead author is Darrell S. Kaufman of the School of Earth Sciences and Environmental Sustainability at Northern Arizona University.