The Arctic and Antarctica

Two Frozen Ends of the Earth

At the very top and very bottom of our planet lie two of the most extreme places on Earth: the Arctic in the north and Antarctica in the south. Both are cold, white and ruled by ice. Yet they are surprisingly different from one another, and telling them apart is the first secret to understanding the poles.

The simplest way to remember it is this: the Arctic is a frozen ocean surrounded by land, while Antarctica is a frozen continent surrounded by ocean. In the north, if you could dig down through the ice at the North Pole, you would reach not solid ground but seawater. In the south, the ice sits on top of a real continent of rock.

In this book we will explore why the poles are so cold, why the Sun behaves so oddly there, which astonishing animals and people survive in the cold, and why these frozen places matter to every one of us — even those living thousands of kilometres away in the warm.

Why the Poles Are So Cold

The poles are not cold because they are further from the Sun — the difference in distance is tiny. They are cold because of the angle at which sunlight reaches them.

Near the Equator, the Sun shines almost straight down, so its energy is concentrated and strong. At the poles, the Sun is always low in the sky, so its rays arrive at a slanting angle and spread thin across the land, like the weak warmth of a torch shone sideways. The same amount of sunlight has to heat a much bigger patch of ground, so it never warms up much.

There is a second reason: ice and snow are brilliant white, and white surfaces reflect sunlight rather than soaking it up. So much of the little warmth that does arrive is simply bounced back into space. This is called the albedo effect, and it helps keep the poles locked in cold. Antarctica is the colder of the two poles, partly because it is high land covered in thick ice, and partly because it is surrounded by cold ocean and wild winds.

The Strange Polar Sun

If you travelled to the poles, the Sun itself would behave in a way that seems almost magical. Because of the way the Earth is tilted as it travels around the Sun, the poles have a single, very long "day" and a single, very long "night" each year.

For months in summer, the Sun never sets at all. It circles around the sky without dropping below the horizon, giving constant daylight even at midnight. This is the famous Midnight Sun. Then, in winter, the opposite happens: the Sun does not rise for months, and the land is locked in a long polar night of darkness and bitter cold.

During those long, dark winters, the polar skies sometimes glow with one of nature's most beautiful sights: the auroras. In the north they are called the Northern Lights, and in the south the Southern Lights. These shimmering curtains of green, pink and purple are made when particles from the Sun crash into gases high in the Earth's atmosphere near the poles.

The Arctic: A Frozen Sea

The Arctic is the region around the North Pole. At its heart is the Arctic Ocean, much of which is covered by floating sea ice. This ice is not solid land — it is frozen seawater drifting on the ocean. It grows in winter and shrinks in summer, breathing in and out with the seasons.

Around the Arctic Ocean lie the northern edges of Asia, Europe and North America, including Canada, Russia, Greenland and the chilly seas of the far north. Unlike Antarctica, the Arctic is home to many land animals — and to people.

The most famous Arctic animal is the polar bear, the largest land predator on Earth, which hunts seals across the sea ice. Walruses, Arctic foxes, snowy owls, reindeer and herds of whales also live here. To meet these and other cold-loving creatures in detail, see the companion book Animals of the Polar Regions.

Antarctica: A Continent Under Ice

Far to the south lies Antarctica, the region around the South Pole. Unlike the Arctic, Antarctica is a true continent — a vast area of land — but you would never know it, because almost all of it is buried under an ice sheet kilometres thick. In some places the ice is more than 4 kilometres deep, hiding whole mountain ranges beneath it.

Antarctica is the coldest, windiest and driest continent on Earth. The lowest temperatures ever recorded anywhere were measured here. Strangely, it is also a kind of desert: so little new snow falls that, by the rules geographers use, much of Antarctica counts as one of the driest places on the planet.

No people live in Antarctica permanently. There are no towns, no farms and no countries that own it. The only humans are scientists and the people who support them, living at research stations for a season or two to study the ice, the oceans, the weather and the stars. You can learn more about the seventh continent in The Seven Continents.

Penguins, Whales and Polar Life

Life at the poles has to be tough. Animals here survive thanks to clever tricks: thick fur, layers of fat called blubber, and bodies built to keep heat in.

In the south, the star animals are penguins. The emperor penguin even breeds during the brutal Antarctic winter, with males huddling together in the dark, balancing eggs on their feet, while temperatures plunge far below freezing. Seals, including the huge leopard seal, hunt in the surrounding waters, and great whales feast on swarms of tiny shrimp-like creatures called krill.

In the north, polar bears rule the ice, while reindeer and musk oxen roam the frozen lands. Here is a fun fact to remember: penguins and polar bears never meet in the wild. Penguins live only in the southern half of the world, and polar bears only in the far north. Pictures that show them together are always make-believe.

People of the Far North

While Antarctica has never had a native human population, the Arctic has been home to people for thousands of years. Several million people live in the Arctic today, including Indigenous peoples such as the Inuit, the Sámi and many others.

These communities learned to survive in one of the harshest climates on Earth long before modern technology. They built shelters from snow and skins, travelled by sled, and hunted seals, fish, whales and reindeer for food, clothing and tools. Their deep knowledge of the ice, the animals and the weather has been passed down through countless generations.

Today, Arctic peoples live in modern towns as well, but many keep their languages, skills and traditions alive. They are also among the first to notice when the polar climate begins to change, because their lives are so closely tied to the ice.

Why the Poles Matter to Everyone

You might think that places so remote could not affect your daily life. In fact, the poles help control the climate of the entire planet — and they are changing fast.

The bright white ice acts like a giant mirror, reflecting sunlight and helping to keep the whole Earth cool. The cold polar oceans also drive great currents that move heat around the globe and shape the weather everywhere. The poles are like the planet's air conditioning.

But the Earth is warming, and the poles are warming faster than almost anywhere else. Sea ice is shrinking, and the great ice sheets on land are slowly melting. When ice that sits on land melts and flows into the sea, it raises sea levels around the whole world, threatening low-lying coasts and cities far from the poles. As the bright ice disappears, less sunlight is reflected and the warming speeds up. To understand the bigger picture, the book Understanding Climate Change explains how it all fits together.

What We Have Learned

We have journeyed to both ends of the Earth. We learned the key difference — the Arctic is a frozen ocean ringed by land, while Antarctica is a frozen continent ringed by ocean — and why the poles are so cold, with their slanting sunlight and reflecting ice.

We saw the strange Midnight Sun, the long polar night and the glowing auroras. We met the polar bears and people of the north, the penguins and scientists of the south, and the clever ways every living thing survives the cold. Finally, we learned that these distant, frozen places help keep the whole planet's climate in balance.

The poles are remote, but they are not separate from us. What happens at the top and bottom of the world reaches every shore on Earth.

Keep exploring the cold: meet the creatures up close in Animals of the Polar Regions, or zoom out to the whole planet in The Seven Continents.