In September 2007, the extent of summer sea ice receded to its lowest record level since satellite measurements began, as captured by the Envisat Advanced Synthetic Aperture Radar. The reduction in ice opened up the Northwest Passage – a long-sought short cut between Europe and Asia that has been historically impassable. The Northwest Passage is shown by the orange line and the Northeast Passage by the blue line. The dark grey represents the ice-free areas, while green denotes areas with sea ice.