The sea and the fjords – Trap Greenland

Greenland is surrounded by vast bodies of water with different temperatures and production conditions, which affect all life in the coastal areas – i.e. areas less than 3 nautical miles from land. Cold polar water that flows south on both sides of the country meets with warm Atlantic water and creates favourable production conditions on the continental shelf.

The location high up north results in considerable seasonal fluctuations in ice conditions and the biological production in the seas. Most of the seas and fjords around Greenland are covered by ice in winter. The exception is Southwest Greenland and the so-called polynyas, which do not freeze even though they are surrounded by sea ice.

The seas, sea currents, ice and the living resources

Map of ocean currents. The cold ocean currents from the Arctic Ocean are shown in light blue and the warm North Atlantic Current is shown in fading red.
TRAP DANMARK EFTER OPLÆG FRA MADS PETER HEIDE-JØRGENSEN

The stretches of sea around Greenland have experienced large fluctuations in both temperature and salinity, and both are also expected to change in the future. From 1920 to 1930, the sea temperature along West Greenland rose by 1.5 ºC, and remained at this high level until the 1960s. During the period 1970 to 1990, the temperature fell, but then rose again, peaking in 2016. Since then, sea temperatures have decreased, but based on the current climate projection, it is expected that the surface temperature in the seas around Greenland will increase by an average of 0.3 ºC per decade until year 2100. This means that, by that time, large areas will be without ice during summer.

The ice around Greenland has also undergone major changes in the past 40 years since the amount of open water has increased dramatically. In Baffin Bay, the sea ice area has fallen by 4 % per decade, and the area currently accounts for only a third of the area in 1979. In the Greenland Sea, the decline is 9 % per decade.

Life in Greenland and the exploration and exploitation of Greenland have always been closely tied to the sea with its living resources, transport options and ice-filled limitations. Hunting of marine mammals and especially whales have driven several people across the ice from Canada, and commercial whalers from Europe have sailed to Greenland. Today, the fishery resources are crucial to society, whereas income from other resources in the sea, e.g. oil and gas, have yet to gain any traction.

Greenland is also located at the gateway to the Northwest Passage, which ill-fated explorers have tried to map for centuries. With reduced ice formation in North Canada, the Northwest Passage may in the future gain new importance as a transport route between the Atlantic and Pacific Oceans.

Baffin Bay and Davis Strait

Baffin Bay lies between northern Canada and Greenland and is a large (690,000 km²) and up to 2,000 m deep basin, which is covered with ice in winter and ice-free in summer. The eastern part of Baffin Bay is shallow with a water depth of less than 200 m. A continental shelf intersected by deep canals connects the deep water outside the continental shelf with the fjords and glaciers along the coast.

To the south, Baffin Bay joins Davis Strait, which stretches with a 300‑600 m deep threshold from Greenland to Canada and forms the link to the North Atlantic. Sea depths in the southern part of Davis Strait are greater than 2,000 m. The eastern part of Davis Strait, unlike Baffin Bay, has a rather narrow continental shelf (less than 50 km).

The narrow and relatively low straits in North Canada constitute the primary supply of cold polar water to Baffin Bay. On the east side along Greenland’s west coast, the West Greenland Current transports warm and salt water of Atlantic origin to the north.

Lincoln Sea, Arctic Basin and Greenland Sea

In March, sea ice typically reaches maximum size, covering an area almost seven times the size of Greenland. As the salt is released when the ice forms, it floats on the seawater.
PATRICK KELLEY, USGS/US GEOLOGICAL SURVEY, CREATIVE COMMONS, 2009

North of Greenland lies the Lincoln Sea. For most of the year, it is covered with perennial sea ice and which sends cold polar water down through Nares Strait to Baffin Bay. Water from the Pacific Ocean, which flows along North Canada, meets Atlantic water in the Lincoln Sea, from where the mixed water passes down the Nares Strait.

The Greenland Sea of about 1,2 million km² off the northern part of East Greenland is adjacent to the Norwegian Sea and the Denmark Strait and constitutes, via Fram Strait, the link between the Arctic Basin and the Atlantic Ocean. The western part is dominated by the cold East Greenland Current which moves south on the Greenland shelf. At Uummannarsuaq (Cape Farewell), the current bends to the north and continues in decreasing strength up to Qeqertarsuup Tunua (Disko Bay). To the east, a tributary of the Gulf Stream moves north with warm Atlantic water, which is cooled in the Greenland Sea and sinks to the bottom.

The Greenland Sea is one of the most important places where the sinking of the warm water from the Gulf Stream takes place. This process is crucial for the circulation in the oceans. With a future increase in the surface temperature in the Greenland Sea, it is believed that this heat exchange, and thus the pump behind the Gulf Stream, could be affected.

Irminger Sea/Denmark Strait

Off Southeast Greenland lies a deep (2,000 m) basin, which is supplied with cold water from the East Greenland Current and warm water from a tributary of the North Atlantic Current. The area, which is called the Irminger Sea, is important for the formation of the Irminger Current, which brings warm water up along West Greenland and thus keeps the sea ice-free in winter and stimulates rich marine production.

Denmark Strait lies in the northern part of the Irminger Sea where cold and heavy polar water sinks beneath the light water from the North Atlantic Current.

Qeqertarsuup Tunua (Disko Bay)

The southwestern part of Qeqertarsuup Tunua has a 700 m deep channel, which supplies the bay with warm water from the West Greenland Current. The bay is usually covered by ice from January to April, but open water all year round has become more common in recent decades.

The Sermeq Kujalleq glacier in the eastern part of Qeqertarsuup Tunua is the largest supplier of icebergs in Greenland. It brings nutrients from land into the sea, and the melting of the light fresh water creates turbulence. The phytoplankton exploits the nutrients which, together with the light, set in motion the food chain.

The fjords

Uummannaq in autumn evening light where fjord ice is forming. In winter, the fjord is covered with thick sea ice, so transport to some settlements is possible by car and truck.
ANINGAAQ R. CARLSEN/VISIT GREENLAND, 2021

There are more than 150 named fjords in Greenland, and on top of this comes a large number of side fjords, e.g. King Oscars Fjord in East Greenland alone has 14 side fjords. The marine production in these fjords varies considerably, depending on the masses of water and active glaciers that supply the fjords with water and sediments.

In the largest fjord in West Greenland, Nuuk Fjord, lies the capital Nuuk. The fjord has an average depth of 250 m, but also has depths over 600 m. It is 190 km long and covers an area of 2,000 km². Fresh water from three glaciers, which lie on land, and melting of icebergs from another three glaciers, which run into the sea, mix in the fjord with more saline water from the West Greenland Current, allowing for a biological production that is atypical for Arctic areas. Only the inner parts of the fjord are covered with ice in winter.

The fjord system in Kangertittivaq (Scoresby Sound) is about 350 km long (about 10,000 km²), and it is the world’s largest fjord. Eleven side fjords with depths of up to 1,000 m branch off around the large Milne Land island. The fjord, which is cold and covered with sea ice from December to June, is supplied with meltwater from 12 glaciers and from the East Greenland Current.

Ice conditions along the coasts

Sea ice can take many different forms – land-fast ice, pack ice, perennial ice, fjord ice, drift ice, just to name a few. West of Greenland has a pulsating annual ice formation in Davis Strait and Baffin Bay. The ice first forms in the northern and western parts of Baffin Bay in December and spreads southwards during winter. Eventually, the ice reaches the coast of Greenland, and the maximum extent is seen in March, when the ice can reach as far south as to Nuuk.

In East Greenland, the ice is always in strong motion since the East Greenland Current carries more than 800,000 km² of ice per year from Fram Strait and further south at 10 km/h. The ice from Fram Strait consists of both perennial and oneyear pack ice from the Arctic Basin, the multiyear sea ice, also called storis (great ice). The storis that drifts with the current down along East Greenland continues for some years around Cape Farewell where it is caught by the West Greenland Current and can drift all the way up to Nuuk Fjord. In recent years, ice exports from Fram Strait have increasingly consisted of one-year ice due to climate change, and storis is now rarely seen along the southern part of West Greenland.

Land-fast ice forms long the coast and inside the fjords in both West and East Greenland and is stable and immobile all the way to the shore. This is the ice that is used for dog sledding in the northern areas. In the northernmost parts of Greenland, the land-fast ice can remain throughout summer, but most fjords are ice-free from June.

Polynyas

All over the Arctic, you find coastal areas that are ice-free throughout winter. These areas are termed using the Russian word ‘polynyas’, and they are found on both the east and west sides of Greenland. The polynyas are formed in the same places every winter and occur either when warm water flow into an area inside the ice throughout winter, or as the result of the wind and current removing the newly formed ice. Polynas can also be formed as a combination of both mechanisms.

The constant formation of new ice in the polynyas leads to brine rejection, which contributes to the nutrient turnover in the water column and thus to the primary production. The polynyas are also characterised by open water in early spring when the sun can stimulate primary production. This means that seabirds can exploit the food chain in the upper part of the water column and thus start producing young in early spring. The polynyas are important for marine mammals because they allow seals and whales to get up for air throughout winter.

One of the most productive polynyas in the Arctic is the North Water Polynya located in Smith Sound between Greenland and Canada. It is kept open by strong northern winds that blow in Smith Sound throughout winter. With the formation of an ice bridge across Smith Sound, the wind gets a blow-off edge where new ice is constantly being pushed south. The North Water Polynya is recognised as a critical habitat for a large number of animal species. The future of the polynya is uncertain since the ice bridge in Smith Sound has become more unstable in recent years.

Another large but rather unproductive polynya is the Northeast Water, located in the northeasternmost corner of Greenland. The third large polynya is located off the Scoresby Sound fjord Kangertittivaq and, like the North Water Polynya, is an important area for a large number of birds and marine mammals.

Marine resources

Fishing for cod with pound nets at Maniitsoq. In 2016, the catch of the inland cod stock increased to 34,000 tonnes, but it has since decreased to half that amount, and it is uncertain whether the catch is sustainable in the long term.
MADS PETER HEIDE-JØRGENSEN, 2013

The primary production in the seas around Greenland shows great seasonal variation, which is due to the six-month ‘winter night’ with no or little sunlight combined with heavy ice cover – and the corresponding intensive period in summer with open water, considerable nutrient supply and sunlight around the clock. The ice dampens the effect of the wind on the mixing and thus the circulation of nutrients in the water column.

In the free water masses, a number of organisms and bacteria live off the spring and summer primary production of planktonic algae. The most important organisms in the grazing in the upper water layers are daphnia and krill, which also constitute the food source for fish larvae, fish, seabirds and marine mammals. In shallow water (less than 200 m), a large part of the algae production sinks to the bottom, where a number of animals survive by filtering particles, e.g. excrement and residues from the production in the water surface. The benthic animals form part of a number of food chains, which include fish, eider, bearded seal and walrus. In deep water, only a small part of the surface algae production reaches the bottom.

Fish and other marine resources

There are about 250 fish species in the seas around Greenland. Mainly the populations that are exploited have been studied, while for most species, it has only been noted that this species has been observed. Fishing for a limited number of species, primarily shrimp, cod and Greenland halibut today constitutes the country’s most important export and accounts for a quarter of the gross domestic product. Fishing is regulated through quotas which distinguish between coastal fishing with small boats and seagoing fishing with large factory trawlers. To support coastal fishing, factory facilities have been established in 11 towns and smaller facilities in several settlements.

The Atlantic cod is perhaps the fishing resource that has had the greatest impact on the country’s development. Kitchen middens have revealed very large fish bones from cod, which shows that the earliest cultures in the country fished for cod. The first reports of cod fishing off Greenland date from the mid-19th century, but from the 1920s, fishing on the banks in West Greenland grew in scale. Fishing peaked in the late 1960s with record catches of half a million tonnes a year. The period from 1920 to 1970 was warm, and the influx of cold water after 1970, meant that cod disappeared from the banks and has not returned in the same numbers since.

Several small stocks of cod that are not particularly affected by temperature fluctuations can be found in the fjords, but these stocks are negligible in comparison with the stock on the banks during the warm period.

Greenland halibut can be found in the cold water masses in both East and West Greenland. Spawning takes place in Davis Strait, and larvae and fry are carried north with the water masses into the banks and into Qeqertarsuup Tunua (Disko Bay). Greenland halibut is also found offshore (more than 3 nautical miles from land) at a depth of 1,000‑1,500 m along the slope of the deep pit of Baffin Bay. Today, Greenland halibut is the most important export fish in Greenland.

The deep-sea shrimp is found mainly on the edge of the banks at depths from 50 m to 600 m where it feeds on worms, dead organic material, algae and various small animals. The shrimp is also a food source for cod, Atlantic halibut, Greenland halibut and salmon. Fishing for deep-sea shrimp started in the 1950s in Qeqertarsuup Tunua, and as fishing for cod declined during the 1960s, shrimp fishing grew more important. Since the 1980s, deep-sea shrimp has been the most economically important fishing resource in Greenland.

Scallops and crabs are fished to a lesser extent and have some economic significance locally.

Other important species for fishing include red perch, which is caught in deep water in Southeast Greenland, lumpfish, which is caught near the coast in West Greenland to exploit their roe, and capelin, which is caught in East Greenland. Fishing for mackerel, herring and blue whiting, which are pelagic species, developed surprisingly rapidly in East Greenland after 2011, but is now in decline. Some bluefin tuna have also been caught in East Greenland. Finally, we have the North Atlantic salmon, which is caught to a lesser extent, and which has a small spawning stock in Nuuk Fjord. Several other species are not part of the fishing, but are important for the ecosystem: polar cod, Arctic cod, sand lance and Greenland shark.