The Loss of Sea Ice
Detailed satellite observations have existed since 1979, and older records, since the mid 1800’s, have also been digitized. Sea ice conditions started to change in the 1980s.
Sea ice extent is a key metric for the reflectivity of sunlight. The rapid decline in sea ice extent, especially in the summer months, is showing a trend that could lead to further positive feedback on the warming of the planet.
Stopping further loss of summer sea ice, and reversing the trend, to go back to the levels experienced in the 1980s would slow down global warming.
By processing the sea-ice extent for each point in the Arctic, we can measure the sea-ice “duration”, as the time a certain portion of sea is covered in ice (at the minimum 15% concentration) through an entire year.
Source: NOAA/NSIDC Climate Data Record of Passive Microwave Sea Ice Concentration, Version 4 (G02202)
Figure: Average sea ice duration in the 1980s.
Figure: Average sea ice duration 2020-22
Source: Difference in sea ice duration between the 1980s and 2020-22
We can observe that very large areas in the Arctic have lost months of sea ice throughout the year, and only the central parts of the Ocean are maintaining the same duration. The loss in volume of sea ice is endangering these areas too.