Norwegian Sea

The Norwegian Sea is a vital marginal sea located northwest of Norway. It sits between the North Sea and the Greenland Sea, while adjoining the Barents Sea to the northeast. This sea is unique because most of its floor is not a shallow continental shelf. Instead, the sea floor lies at an average depth of about two kilometres.

This depth allows the sea to act as a massive reservoir for heat. Because of this heat absorption, the Norwegian Sea remains ice-free throughout the entire year. This distinguishes it from many other Arctic seas that freeze over.

The formation of this sea began approximately 250 million years ago. During this time, the Eurasian Plate and the North American Plate began to move apart. As these tectonic plates separated, the narrow sea between them widened and deepened. The current continental slope marks the ancient border between Norway and Greenland from that era.

Later, during the last ice age, massive glaciers several kilometres high shaped the coasts. These glaciers pushed into the land to create deep fjords. They also removed parts of the crust into the sea, extending the continental slopes near the Lofoten Islands.

Water movement in the Norwegian Sea is driven by complex currents. The warm, salty North Atlantic Current flows in from the Atlantic Ocean. This current can reach speeds of 10 Sv, which is ten million cubic metres per second. It reaches a maximum depth of about 700 metres near the Lofoten Islands.

Another current, the Norwegian Current, originates in the North Sea. It is colder and has less salt, or salinity, than the Atlantic water. In the middle water layer, the East Iceland Current transports cold water south toward Iceland. This current's strength depends on the pressure difference between the Icelandic Low and the Azores High.

The sea is also defined by its deep-sea layers and basins. Two large basins are separated by a low ridge that reaches a depth of 3,000 metres. The southern basin is the larger and deeper of the two. It contains areas between 3,500 and 4,000 metres deep. The northern basin is shallower, ranging from 3,200 to 3,300 metres.

Below 2,000 metres, a layer called Norwegian Sea Deep Water exists. This water is very cold, with temperatures dropping to −1 °C at the ocean floor. It is also quite old and contains more nutrients but less oxygen than surrounding waters.

Geography and underwater structures create many different environments. To the west, the Scotland-Greenland Ridge separates the Norwegian Sea from the North Atlantic. This ridge is relatively shallow, averaging only 500 metres deep. In the north, the Jan Mayen Ridge and Mohns Ridge lie at depths of 2,000 metres.

The Norwegian continental shelf is between 40 and 200 kilometres wide. It contains irregular peaks and trenches covered in gravel, sand, and mud. These trenches are important because fish use them as spawning grounds.

Biological life and human industry both rely on these waters. The coastal zones are incredibly rich in fish. For example, cod visit the sea from the North Atlantic or Barents Sea to spawn.

Humans also look to the sea for energy resources. Rich deposits of oil and natural gas are found beneath the sea bottom. Commercial exploration currently takes place in areas where the water depth is up to one kilometre.

Even the movement of the tides is significant. The tides are semi-diurnal, meaning they rise twice a day to a height of about 3.3 metres.

The Norwegian Sea plays a massive role in the global climate system. Recent research suggests its large volume of water is more important for Norway's mild winters than the Gulf Stream. This is due to the sea's massive heat absorption capacity. The interaction between warm water and cold air in the winter drives important convection.

This process helps regulate the regional climate. Even the air pressure is affected, as the Norwegian Sea often has the lowest air pressure in the entire Arctic during winter.