Where are the polar regions?
The polar regions are the areas around the two ends of Earth's axis. They are usually taken as the lands and seas inside the Arctic Circle (66.5° N) and the Antarctic Circle (66.5° S).
- Arctic: the Arctic Ocean, covered by sea ice (1–4 m thick), surrounded by the northern edges of the continents and islands such as Greenland.
- Antarctica: a continent of about 14 million km², nearly 98% covered by an ice sheet with an average thickness of about 2 km (up to about 4.8 km). It holds about 70% of the world's fresh water.
The lowest air temperature measured on Earth, about −89 °C, was recorded in Antarctica.
Why are the poles so cold?
- Low sun angle: sunlight strikes at a slant, so the same energy spreads over a bigger area.
- Longer path through air: slanting rays pass through more atmosphere and lose more energy.
- High albedo: snow and ice reflect up to 80–90% of sunlight.
- Long polar night: for months there is no sunlight at all.
Antarctica is colder than the Arctic because it is high (thick ice on land) and far from warm ocean water. Polar areas get very little precipitation, so they are cold deserts.
Midnight sun and polar night
Earth's axis is tilted 23.5°. Around June the North Pole leans toward the Sun: places north of the Arctic Circle see the Sun for 24 hours (midnight sun), while Antarctica is in polar night. Around December it is the other way round. At the poles themselves there are about six months of light and six months of dark. Auroras (northern and southern lights) are often seen in the long polar nights.
Life in the cold: plants, animals and people
Near the Arctic edge is the tundra: mosses, lichens, grasses and dwarf shrubs on frozen ground (permafrost). Animals survive with thick fur, fat (blubber), small ears and migration: polar bears, Arctic foxes, reindeer (caribou), seals, walruses and whales. Antarctica has almost no land plants; life is in the sea: krill, fish, seals, whales and penguins.
About 4 million people live in the Arctic, including Indigenous peoples such as the Inuit, Sami and Nenets, who traditionally herd reindeer, fish and hunt. Antarctica has no permanent population, only a few thousand scientists and staff.
Climate research and climate change
Ice cores drilled from ice sheets contain air bubbles and dust from up to about 800,000 years ago, showing past temperatures and carbon dioxide levels. Research stations also watch the ozone hole, weather and sea ice by satellite.
The Arctic is warming about three to four times faster than the global average. Less sea ice means less reflection and more absorption (albedo feedback). Melting land ice (Greenland, Antarctica) raises sea level; melting floating sea ice does not, but it changes habitats and weather. Thawing permafrost can release greenhouse gases.
Cooperation and competing interests
The Antarctic Treaty (signed 1959, in force 1961) sets Antarctica aside for peace and science: no military activity, no nuclear tests or waste, free exchange of scientific data. A later protocol (1991) bans mining. India joined in 1983. In the Arctic there is no single treaty; the Arctic Council lets Arctic states and Indigenous groups work together, and the UN Convention on the Law of the Sea guides use of the ocean. As sea ice shrinks, new shipping routes, fishing and oil and gas raise questions about environment, Indigenous rights and fair cooperation.
Try it at home
Shine a torch straight down on a sheet of paper, then tilt it. Draw around the light patch each time. The tilted patch is bigger and dimmer: that is why poles are cold. Then put one ice cube on a white plate and one on a black plate in the sun: which melts first?
Key formulas and definitions
- Arctic Circle ≈ 66.5° N; Antarctic Circle ≈ 66.5° S
- Axial tilt = 23.5°
- Albedo = reflected light ÷ incoming light (ice ≈ 0.8, ocean ≈ 0.06)
- Midnight sun: 24 h daylight; polar night: 24 h dark
- Antarctic Treaty: 1959 (in force 1961)
Worked examples
1. Sunlight of 1,000 W hits 1 m² at the equator. Near the pole the same beam spreads over 2 m². How much falls on each square metre there?
Energy per m² = 1,000 W ÷ 2 m² = 500 W/m², half as much. That is why it is colder.
2. Ice reflects 80% of sunlight, open ocean 6%. If 100 units of sunlight fall, how much more is absorbed when ice changes to ocean?
Ice absorbs 100 − 80 = 20 units; ocean absorbs 100 − 6 = 94 units. Extra absorbed = 94 − 20 = 74 units, so the water warms and melts more ice.
3. An ice cube floating in a glass melts. Does the water level rise? Link this to sea level.
No. Floating ice already pushes aside its own weight of water. So melting Arctic sea ice barely changes sea level, but melting ice on land (Greenland, Antarctica) adds new water to the ocean and raises sea level.
Common mistakes
- Saying the Arctic is a continent. It is mostly ocean; Antarctica is the continent.
- Thinking penguins and polar bears live together. Polar bears are Arctic; wild penguins are mostly in the Southern Hemisphere.
- Believing all melting ice raises sea level. Floating sea ice does not; land ice does.
- Thinking the poles are cold because they are far from the Sun. The distance difference is tiny; the low sun angle and ice reflection matter.