From the time Europeans discovered the North American continent to the mid-twentieth century, sailors searched for a northwest passage that would connect the Atlantic Ocean (and Europe) to the Pacific Ocean (and Asia). No such passage exists through the continent, but during the summer, a northwest route through the Arctic opens up.
This natural gatekeeper, which prevents sea ice from exiting the Arctic Ocean and drifting southward into Baffin Bay, was still intact in late May 2020.
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.
This image shows sea ice around the Northwest Passage as observed by the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) aboard NASA’s Aqua satellite on August 22, 2007. McClure Strait, Parry Channel, Victoria Strait, and McClintock Channel (north of Victoria Strait), all appear nearly ice-free. North of McClure Strait, an area of sea ice remains, but it is fragmented.
On September 15, 2007, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured a largely cloud-free image of the Northwest Passage. Although the sea route had been characterized as nearly open weeks earlier, persistent cloud cover prevented a MODIS true-color image of the open route.