The most visible change in the Arctic region in recent years has been the rapid decline of the perennial ice cover. The perennial ice is the portion of the sea ice floating on the surface of the ocean that survives the summer. This ice that spans multiple years represents the thickest component of the sea ice cover. This visualization shows the perennial Arctic sea ice from 1980 to 2012. The grey disk at the North Pole indicates the region where no satellite data is collected. A graph overlay shows the area's size measured in million square kilometers for each year. The '1980','2008', and '2012' data points are highlighted on the graph.
