The Arctic Ocean is the smallest of the world’s oceans and it has very cold water. It is often called the Earth’s icebox because it helps cool the planet and shapes its jet stream. This makes it a very important part of the global weather system and what happens in the Arctic influences conditions elsewhere on the globe, including the temperature of seawater.
The surface of the Arctic Ocean has a layer of freshwater from melting ice and Arctic rivers that quasi-floats on top of denser, saltier ocean water. When this surface water nears the freezing point, it becomes very dense and sinks. This is why explorer Fridtjof Nansen described the Arctic Ocean as “upside-down” — a description that still holds today.
This circulation is also a key reason why the Arctic sea ice tends to be thicker than Antarctic sea ice, which is much less consolidated and more mobile. The ice floes are more likely to bump into each other and pile up, which allows them to become thicker over time.
Marine life thrives in the Arctic because it’s rich with nutrients. Jellies, shrimp, and plankton form the base of the Arctic marine food web, feeding on the bacteria and algae that live in the cold, circulating water. This in turn provides a source of food for fish, seals, and walruses. The Arctic is also home to a variety of baleen whales and toothed whales that prey on other carnivorous animals.