The Arctic is the area around the North Pole, at the top of the Earth. Most of the Arctic is ocean, and the Arctic Ocean is bordered by Greenland, Canada, Norway, Alaska and Russia. Sea ice is frozen seawater that floats on the ocean. Arctic and Antarctic sea ice differ mainly because of their different geographies. The Arctic is a semi-enclosed ocean almost completely surrounded by land, and Antarctica is a continent surrounded by ocean. Antarctica's sea ice grows in winter, when the ocean around the continent freezes.

The Arctic has strange seasons of light. On about June 21, the June solstice, the Arctic has 24 hours of sunshine. On about December 21 the Sun does not rise, and in winter the Arctic is dark and cold. On land the ground can be permafrost, which is ground that stays frozen for at least two years. So the Arctic has long days in summer and long nights in winter.

Antarctica is a continent, and a huge sheet of ice covers it. The Antarctic Ice Sheet is the largest single mass of ice on Earth. As of November 2026, it covers almost 14 million square kilometers, about the area of the lower 48 states and Mexico together. Ice shelves are floating sheets of ice that are connected to the land. Katabatic winds start when cold, dense air over the high Antarctic ice flows downhill. They blow hard near the coast.

As of November 2026, Antarctica is extremely cold and dry. Much of it is a desert, because very little snow falls in the middle of the continent. Antarctica has no native people, but scientists and other people live and work at research stations there. Let's see how the treaty works. The Antarctic Treaty was signed in 1959 by 12 countries. It sets Antarctica aside for peaceful science. It also freezes territorial claims, so no new claims can be made while it is in force.

Polar bears live in the Arctic and eat seals. They hunt by waiting at seal breathing holes in the ice. Polar bears are strong swimmers, and they paddle with their large front paws. A mother polar bear digs a den in the snow and has her cubs there in winter, usually twins. Narwhals live in the Arctic Ocean, and a male narwhal's tusk is a tooth that grows out through the front of its jaw. Seals keep warm in cold water with a thick layer of fat called blubber.

Emperor penguins are birds that cannot fly, and they live in Antarctica. They are the largest penguins. Emperor penguin fathers keep the single egg warm on their feet for about two months, without eating. The penguins also huddle together to keep warm. Antarctic krill are small, shrimp-like animals that most of the larger animals in the region eat. Leopard seals eat penguins and other seals. Polar bears do not live in Antarctica, and penguins do not live in the Arctic.

Words to know

• permafrost: frozen ground
• blubber: thick body fat
• krill: tiny sea animals
• treaty: signed agreement