Minimum Arctic sea ice cover. Composite satellite image centred on eastern Asia showing the extent of minimum seasonal ice cover (white). Data for Arctic sea ice extent (top) was collected on September 21 2005, the day on which sea ice was at the minimum extent for the year. The extent of Arctic sea ice cover has decresed significantly in recent years, a phenomenon attributed to climate change. Data for landcover is the average since September 2004. Data obtained by the Terra and Aqua satellites.