Norwegian Sea
The Norwegian Sea began to form approximately 250 million years ago when the Eurasian Plate and the North American Plate started moving apart. This movement widened and deepened an existing narrow shelf sea between Norway and Greenland. The present continental slope marks the border that existed at that ancient time, extending east from Svalbard and southwest between Britain and the Faroes. Most of the bottom lies at a great depth of about two kilometres on average, unlike many other seas where the floor is part of a continental shelf.
Two deep basins exist within this vast expanse, separated by a low ridge with its deepest point reaching 3,000 metres. The southern basin is larger and deeper, containing large areas between 3,500 and 4,000 metres deep. The northern basin is shallower at 3,200, 3,300 metres but contains individual sites going down to 3,500 metres. Settling of the shelf after the separation of continents resulted in landslides such as the Storegga Slide about 8,000 years ago that induced a major tsunami.
To the south lies the European continental shelf and the North Sea, while to the east is the Eurasian continental shelf with the Barents Sea. To the west, the Scotland-Greenland Ridge separates the Norwegian Sea from the North Atlantic. This ridge averages only 500 metres deep, though it reaches 850 metres in a few places. Submarine thresholds and continental slopes mark the borders of these basins with adjacent seas.
Four major water masses originating in the Atlantic and Arctic oceans meet in the Norwegian Sea, creating currents fundamental for global climate. The warm, salty North Atlantic Current flows in from the Atlantic Ocean with a speed of 10 Sv (1 Sv = million m3/s). Its maximum depth is 700 metres at the Lofoten Islands, though it normally stays within 500 metres. Part of this current passes through the Faroe-Shetland Channel with high salinity of 35.3‰ due to increased evaporation from the warm European climate.
Another part passes through the Greenland-Scotland trench between the Faroe Islands and Iceland, where water has mean salinity between 35 and 35.2‰. The flow shows strong seasonal variations and can be twice as high in winter as in summer. While at the Faroe-Shetland Channel it has a temperature of about 9.5 °C, it cools to about 5 °C at Svalbard and releases energy of about 250 terawatts to the environment.
The convection between relatively warm water and cold air in winter plays an important role in the Arctic climate. Temperatures rose between 1920 and 1960, while storm frequency decreased during that period. Storminess was relatively high between 1880 and 1910 before recovering to original levels. In contrast to the Greenland Sea and Arctic seas, the Norwegian Sea remains ice-free year round owing to its warm currents.
Most aquatic life in the Norwegian Sea is concentrated in upper layers, with only 2% of biomass produced at depths below 1,000 metres. The blooming of phytoplankton peaks around the 20th of May, dominated by chlorophyll and diatoms such as Thalassiosira and Chaetoceros. After the spring bloom, haptophytes of the genus Phaecocystis pouchetti become dominant. Zooplankton is mostly represented by copepods Calanus finmarchicus and Calanus hyperboreus, where the former occurs about four times more often than the latter.
Shrimp of the species Pandalus borealis play an important role in fish diets, particularly cod and blue whiting, occurring at depths between 200 and 300 metres. A special feature of the Norwegian Sea is extensive coral reefs of Lophelia pertusa providing shelter to various fish species. These corals are widespread in many peripheral areas but never reach such amounts and concentrations as on the Norwegian continental slopes.
The Norwegian coastal waters serve as the most important spawning ground for herring populations of the North Atlantic, with hatching occurring in March. The eggs float to the surface and wash off the coast by the northward current. While a small population remains in fjords along the northern Norwegian coast, the majority spends summer in the Barents Sea feeding on rich plankton. Upon reaching puberty, herring returns to the Norwegian Sea.
For centuries, the disappearance of ships from the Norwegian Sea due to natural disasters induced legends of monsters that stopped and sank vessels. As late as 1845, the Encyclopædia metropolitana contained a multi-page review by Erik Pontoppidan (1698, 1764) on ship-sinking sea monsters half a mile in size. Many legends might be based on the work Historia de gentibus septentrionalibus of 1539 by Olaus Magnus, which described kraken and maelstroms of the region.
The first reasonably reliable map of northern Europe, the Carta marina of 1539, represents the Norwegian Sea as coastal waters and shows nothing north of the North Cape. Jan Mayen island was discovered in 1607 and became an important base for Dutch whalers. The Dutchman Willem Barents discovered Bear Island and Svalbard, which were then used by Russian whalers called pomors.
Systematic oceanographic research started in the late 19th century when declines in cod and herring yields off Lofoten prompted government investigation. Zoologist Georg Ossian Sars and meteorologist Henrik Mohn persuaded the government in 1874 to send out a scientific expedition. Between 1876 and 1878 they explored much of the sea aboard Vøringen. The data obtained allowed Mohn to establish the first dynamic model of ocean currents incorporating winds, pressure differences, temperature, and salinity.
Until the 20th century, coasts of the Norwegian Sea were sparsely populated, so shipping focused on fishing, whaling, and occasional coastal transportation. Since the late 19th century, the Norwegian Coastal Express line has connected south with north Norway by at least one trip daily. The importance of shipping increased with expansion of Russian and Soviet navies in the Barents Sea and development of international routes to the Atlantic through Baltic Sea, Kattegat, Skagerrak, and North Sea.
The Norwegian Sea provides direct route from Atlantic to Russian ports like Murmansk, Arkhangelsk, and Kandalaksha, which link directly to central Russia. This route was extensively used for supplies during World War II. Of 811 US ships, 720 reached Russian ports, bringing some 4 million tonnes including about 5,000 tanks and 7,000 aircraft. Allies lost 18 convoys and 89 merchant ships on this route.
Major operations of German Navy against convoys included PQ 17 in July 1942, Battle of Barents Sea in December 1942, and Battle of North Cape in December 1943. These occurred around border between Norwegian Sea and Barents Sea near North Cape. Navigation declined after World War II but intensified in 1960s, 70s with Soviet Northern Fleet expansion.
Most important products of Norwegian Sea are no longer fish but oil and especially gas found under ocean floor. Norway started undersea oil production in 1993, followed by development of Huldra gas field in 2001. Large depth and harsh waters pose significant technical challenges for offshore drilling. Drilling at depths exceeding 500 metres has been conducted since 1995, though only few deep gas fields explored commercially.
The most important current project is Ormen Lange at depth 800, 1,100 m where gas production started in 2007. With reserves, it is major Norwegian gas field connected to Langeled pipeline, currently world's longest underwater pipeline. Several other gas fields are being developed. As of 2019, estimated 6.5 hm3 of crude oil exists in Norwegian Sea with expectation to increase production until 2025.
A particular challenge is Kristin field where temperature reaches as high as 170 °C and gas pressure exceeds 900 bar (900 times normal pressure). Further north lie Norne and Snøhvit fields. The large depth and harsh conditions make these operations technically demanding compared to shallower continental shelf areas.
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Common questions
When did the Norwegian Sea begin to form?
The Norwegian Sea began to form approximately 250 million years ago when the Eurasian Plate and the North American Plate started moving apart. This movement widened and deepened an existing narrow shelf sea between Norway and Greenland.
How deep are the basins in the Norwegian Sea?
Two deep basins exist within this vast expanse, separated by a low ridge with its deepest point reaching 3,000 metres. The southern basin is larger and deeper, containing large areas between 3,500 and 4,000 metres deep.
What marine life dominates the Norwegian Sea during spring?
The blooming of phytoplankton peaks around the 20th of May, dominated by chlorophyll and diatoms such as Thalassiosira and Chaetoceros. After the spring bloom, haptophytes of the genus Phaecocystis pouchetti become dominant.
Who discovered Jan Mayen island and when was it found?
Jan Mayen island was discovered in 1607 and became an important base for Dutch whalers. The discovery occurred after the Carta marina of 1539 represented the Norwegian Sea as coastal waters.
When did systematic oceanographic research start on the Norwegian Sea?
Systematic oceanographic research started in the late 19th century when declines in cod and herring yields off Lofoten prompted government investigation. Zoologist Georg Ossian Sars and meteorologist Henrik Mohn persuaded the government in 1874 to send out a scientific expedition.