Read here. McKay et al. research PDF download. Peer-reviewed study analyzing 9,000 years of sediment core data (two different types of sediment cores) from the west Arctic Ocean area confirms what was learned from the Greenland ice cores: the Medieval and Roman periods experienced higher temperatures than the world's present climate. See top chart, Fig. A. (click on image to enlarge)
[Note: Blue bars on y-axis of both figures indicate range of modern measurements. The open and closed markers for both figures represent the results from the two sediment cores. The red-shaded areas represent warming periods as found within the sediment cores. The authors contend the red-shaded areas are associated with an evident 2,500 year period of oscillation that naturally occurs.]
In addition, this study was able to determine the approximate sea ice coverage (see bottom chart, Fig. B) over the last 9,000 years. As one would expect, and the bottom chart data reveals, the actual sea ice coverage would be less over the term of a calendar year when the sea-surface temperatures were higher.
Obviously, the "death spiral" of Arctic sea ice that big-government paid scientists like to frighten MSM reporters with (about the current Arctic conditions) has happened multiple times before. These "death spirals" are solely due to natural climate variation - literally, humans don't cause these sea-ice death spirals and humans can do nothing to stop them from happening.
The final conclusion of authors: Modern surface temperatures of west Arctic are well below historical/ancient temperatures. Modern sea-ice coverage is well above the 9,000 year average of the past. Neither modern measurement is "unprecedented" as claimed by global warming alarmists.
The readers can also conclude the following from both this new evidence and the previous Greenland ice core data: Polar bears and walruses are not at risk since both species survived much warmer temperatures and significantly less ice in the past.