Arctic ice pack

The Arctic ice pack is the sea ice covering the Arctic Ocean and the waters around it. It shrinks through spring and summer to its lowest extent around mid September and then rebuilds through autumn and winter, so that its summer extent is only about half its winter extent. Roughly 28 percent of the pack persists year round as thicker multi year ice, typically 3 to 4 meters thick and reaching as much as 20 meters in pressure ridges, though the pack as a whole has been shrinking over recent decades as part of a broader shift in Arctic climate conditions. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/