This visualization shows the age of the Arctic sea ice between 1984 and 2019. Younger sea ice, or first-year ice, is shown in a dark shade of blue while the ice that is four years old or older is shown as white.
A graph displayed in the upper left corner quantifies the area covered sea ice 4 or more years old in millions of square kilometers.
One significant change in the Arctic region in recent years has been the rapid decline in perennial sea ice.
Perennial sea ice, also known as multi-year ice, is the portion of the sea ice that survives the summer melt season.
Perennial ice may have a life-span of nine years or more and represents the thickest component of the sea ice; perennial ice can grow up to four meters thick.
By contrast, first year ice that grows during a single winter is generally at most two meters thick.
This animation shows the seasonal variability of the ice, growing in the Arctic winter and melting in the summer.
In addition, this also shows the changes from year to year.
A graph in the upper left corner the quantifies the change over time by showing the area covered by sea ice that is 4 years old or older in millions of square kilometers.
This graph also includes a memory bar - the vertical green bar that indicates the maximum value seen thus far in the animation for the given week being displayed.
For example, when viewing the sea ice age for the first week in September, the memory bar will display the maximum value seen for the first week of September in all prior years from the beginning of the animation (1984).
In addition, a violet bar indicates the weeks's average area covered by sea ice greater than 4 years of age during the the 20-year time period from 1984 through 2003.
Note that data for the sea ice age is not available along the coastlines.
The region where data is not available is shown in a dark lavender color.
Visualizers: Cindy Starr (lead), Horace Mitchell
Arctic sea ice likely reached its 2019 minimum extent of 1.60 million square miles (4.15 million square kilometers) on Sept. 18, tied for second lowest summertime extent in the satellite record, according to NASA and the National Snow and Ice Data Center.
The Arctic sea ice cap is an expanse of frozen seawater floating on top of the Arctic Ocean and neighboring seas.
Every year, it expands and thickens during the fall and winter and grows smaller and thinner during the spring and summer.
But in the past decades, increasing temperatures have caused marked decreases in the Arctic sea ice extents in all seasons, with particularly rapid reductions in the minimum end-of-summer ice extent.
The shrinking of the Arctic sea ice cover can ultimately affect local ecosystems, global weather patterns, and the circulation of the oceans.