Sea ice is found floating around on the icy waters of The Arctic. It’s also found floating around the continent of Antarctica. Sea ice is always on the move. It crunches and grinds its way across the polar regions with the wind and ocean currents.
Sea ice is an important habitat for seals, walrus and polar bears in the Arctic (to the far North). They use the sea ice to ambush their prey, eat their catch, travel on the ocean currents and have a rest. The Arctic seals use the sea ice as a place to have their babies, hunt and rest.
In The Arctic the sea ice has been getting smaller and thinner for the past 50 years. This makes it harder for creatures like the polar bear to hunt. In Antarctica (to the far South) the sea ice grows around the huge continent in the southern winter. The extra sea ice makes Antarctica grow to more than twice it’s normal size. The sea ice then mostly melts again in the summer and drifts out to sea.
Sea ice is not the same as icebergs. Icebergs form when a glacier drops lumps of ice into the ocean (calving). This is ice that had formed on the land. Sea ice forms on the sea when the water becomes so cold that a thin layer on the top of the water freezes. This ice can be up to two metres thick. Sea ice also plays an important role in our planets climate. The summer sunlight is reflected back into space by the bright white colour of the ice floating on the ocean. When the sea ice melts less sunlight is reflected into space. More sunlight is soaked up by the dark ocean. The warmth from this sunlight melts more ice. This means less sunlight is reflected into space because the dark ocean soaks up more light. More dark ocean means less reflection and more heat.