Each winter sea ice forms over the salty waters of frigid northeastern Canada's Hudson Bay. As sunlight lengthens and weather warms, ice begins to break up and melt, with retreat typically starting in May and melt-out completed sometime in July. Since the 1970s, the timing of sea ice breakup in Hudson Bay has changed, with melting beginning earlier in the spring.
The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite captured this a true-color image of Hudson Bay on March 26, 2013. Although snow still covers the surrounding land, ice has already begun to retreat from much of the eastern shore of the Bay visible in the image.
A ring of bright white ice remains solidly frozen around the Belcher Islands in the southeast section of the Bay, but this ring is surrounded by blue waters and large chunks of ice. In the southwest, a similar situation is seen at Akimiski Island. The shelf of bright white ice gives way to open water in the south, as well as fractured, blue-tinted ice. The blue tint generally indicates water logging as ice begins to soften.
The Aqua satellite captured a similar image of early ice melt on Hudson Bay on April 6, 2012. That image can be viewed at: http://modis.gsfc.nasa.gov/gallery/individual.php?db_date=2012-04-19 .