Arctic Ice

The icy, white landscape of the Arctic may seem hostile and monotonous at first glance, but not only does a rich variety of life inhabit the polar region, the Arctic ice itself is also diverse. Constantly in motion and ever changing, ice is not always the same.Sea ice is one of the most common forms of ice in the Arctic. It forms when the water of the polar sea freezes at the frigid temperatures of the air. When the cold air touches the sea surface not yet covered by ice, small ice crystals form in the salty water of the polar sea. With sustained cold, more ice crystals accumulate until a slush of ice forms on the sea surface. If the ocean is calm, the slush freezes into a thin layer of ice called Nilas. However, when the wind picks up and waves become larger, the slush moves back and forth, forming round, pancake-like ice floes. This pancake ice can have diameters ranging from 30 cm to 3 meters. Winds and currents push these delicate ice layers together, creating drifting ice floes. Sea ice floes have a short lifespan; one-year sea ice is about 1.5 meters thick, while multi-year sea ice can be up to 10 meters thick.

The Arctic wouldn’t be the Arctic as we know it without sea ice. It extends for thousands of kilometres across the Arctic Ocean, appearing as a white expanse covered in snow, seemingly stretching to the end of the horizon. This seemingly endless expanse of compressed ice floes is called pack ice. However, when winds and ocean currents set the sea ice in motion, it creaks and breaks apart or piles up into meter-high ridges, forming jagged structures of pressure ice. Surrounded by coastal areas, sea ice forms a compact, floating ice mass that moves around the North Pole. The landmasses surrounding the Arctic are also covered in ice. While permafrost, a layer of soil, rock, and perpetual ice, extends hundreds of meters deep into the ground, protecting it from erosion, the ice masses of the large ice sheets tower over the land and extend as glacier tongues far into the Arctic Sea. The primary source for the formation of land ice is snow. When snow falls lightly on the areas around the Arctic, it lands on additional snow layers covering the ice sheets. Over time, these snow layers are compressed into a compact mass of ice that appears slightly bluish. Due to its weight, the ice from these glaciers moves slowly through the polar landscape, flowing from the canter to the edges. This movement continues until the glaciers flow into the polar sea, pushing out as icy cliffs of ice and snow above and below the water surface. These glaciers protruding into the water are called shelves. When large chunks of glaciers break off at the edge of the ice shelf, it’s referred to as calving. These glacier fragments of freshwater ice are recognizable by their white colour and distinctive shapes as they float as icebergs across the sea.