THIS LINK to NSDIC will update you on the state of the Northwest Passage.
What does this online analysis provide?
The online information we offer in this section includes:
Daily images of near-real-time Arctic sea ice conditions (above right)
Monthly scientific analysis year-round, with more frequent updates during the melt season or as conditions warrant
Previous news and analysis and general information about sea ice (right navigation)
RSS feed for automatic notification of new analyses.
Please credit the National Snow and Ice Data Center for image or content use unless otherwise noted beneath each image. Sign up for the Arctic Sea Ice News RSS feed for automatic notification of analysis updates.
Update: Hat tip to reader Jim Sattersfield for this link to Geology.com.
There is also a short history of three trips through the Passage.
Update 2: Tx1 sends this chart on temp and CO2:
Update 3: Long term CO2 and temperature