In the Arctic, sea ice extent fluctuates with the seasons. It reaches its peak extent in March, near the end of Northern Hemisphere winter, and its minimum extent in September, at the end of the summer thaw. In September 2007, Arctic sea ice extent was the smallest area on record since satellites began collecting measurements about 30 years ago.
In 1984, there were 1.86 million square kilometers of old ice spread across the Arctic at its yearly minimum extent. In September 2016, there were only 110,000 square kilometers of old ice left.