Now, this is what I call a cool tool:
Researchers at the University of Alaska Fairbanks have developed a "web based atlas to let users view historical sea ice data collected between the mid-1800s and today, and compiled for display on an interactive map of the seas surrounding northern Alaska". Here's an overview of all the data sources they used to compile the historical sea ice atlas.
More background info in this Alaska Dispatch article:
New sea ice map offers a long-term look
at climate change
Mining more than a century of sea ice observations, including from 19th century Yankee whalers and 20th century Arctic wildcatters, researchers at the University of Alaska Fairbanks have put together an expansive view of climate change that lets web surfers track the ice pack off Alaska for decades.
The interactive digital map, dubbed the Sea Ice Atlas, allows viewers to watch the ice around Alaska shrink and grow -- but mostly shrink -- during a period of their choosing, month by month or year by year.
To create the play-by-play of diminishing sea ice, researchers relied on space-age data -- satellite images collected since 1979 -- plus decades of older information collected from ship decks, shorelines and airplanes.