Kinnard et al 2011 report a highly hockey-stick shaped reconstruction of sea ice. (For a different perspective based on Holocene ocean sediments under the Ellesmere Island ice shelf, see the recent Antoniades et al (PNAS...
Two interesting new proxy studies out recently, one with a meticulous archive, one without. Kinnard et al 2011 (Nature) here is a proxy reconstruction using 69 proxies to reconstruct Arctic sea ice. It contains a comprehensive...