Forces of Change

What is the Arctic?

The Arctic is the Earth’s northernmost region. Mostly comprised of ocean, the Arctic can be defined in many ways. Among them:

Arctic Circle

An imaginary line around the Earth at 66° 33’ N above which the sun does not completely set on the summer solstice.

Polar Treeline

The northernmost limit above which trees don’t grow.


The areas at high latitudes where the average summer temperature does not rise above 10°C (50°F).


Various geographical boundaries set by the eight nations with territory in the Arctic.

Images self-advance through the four topics
Maps The M Factory © Smithsonian Institution