September Arctic Sea Ice

Satellite-based passive microwave images of sea ice have provided a reliable tool for continuously monitoring changes in the Arctic ice since 1979. During Northern Hemisphere spring and summer months, the Arctic sea ice melts considerably, usually reaching its minimum extent in September, before colder weather begins to cause ice cover to increase during fall and winter months. This series of images shows Arctic sea ice extent for a selection of years using data from AMSR-E and AMSR2. The burgundy area represents the median sea ice extent observed by satellite sensors in September from 1979 to 2000.

Over the last few decades, the average global temperature has been on the rise—and temperatures in the Arctic have risen at nearly twice the rate as temperatures elsewhere on the planet. As temperatures rise in the Arctic, the extent of sea ice declines. Sea ice is highly reflective of the sun’s energy; therefore, reductions in sea ice impact Earth’s radiation budget. Rather than reflecting most of the sun’s energy, ice-free areas absorb sunlight causing subsequent warming of the ocean.