Baltic Sea

From Open Encyclopedia

The Baltic Sea is located in Northern Europe, from 53 deg. to 66 deg. north latitude and from 20 deg. to 26 deg. east longitude. It is bounded by the Scandinavian Peninsula, the mainlands of Northern Europe, Eastern Europe, Central Europe, and the Danish islands. It drains into the Kattegat by way of the Öresund, the Great Belt and the Little Belt. Kattegat then continues in the Skagerrak into the North Sea and the Atlantic Ocean. The Baltic Sea is linked to the White Sea by the White Sea Canal and directly to the North Sea by the Kiel Canal.

Image:Baltic sea map.jpg

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Name

The first one to name it the Baltic Sea was Adam of Bremen and he seems to have based it on a large island, Baltia, mentioned by Xenophon and located in northern Europe.

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Etymology

It is possibly connected to the Germanic belt, a name used for some of the Danish straits, while others claim it to be derived from Latin balteus (belt)^{[{{fullurl:}}#endnote_Latin-etymology]}. From this use, Baltic has been applied to the Baltic countries. Another proposed derivation from the Indo-European root *bhel meaning white, shining seems speculative. Note that 'baltas' means 'white' even in today's Lithuanian language.

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The name in other languages

The Baltic Sea is known by the equivalents of "East Sea", "West Sea", or "Baltic Sea" in different languages:

In the Germanic languages except English East Sea is used: Danish (Østersøen), Dutch (Oostzee), German (Ostsee), Norwegian (Østersjøen), and Swedish (Östersjön); in addition, Finnish, a Balto-Finnic language has calqued the Swedish term as Itämeri, disregarding the geography; the sea is west of Finland.

In another Balto-Finnic language, Estonian, it is called the West Sea (Läänemeri).

Baltic Sea is used in English; in Latin (Mare Balticum) and the Romance languages French (Mer Baltique), Italian (Mar Baltico), Romanian (Marea Baltică) and Spanish (Mar Báltico); in the Slavic languages Polish (Morze Bałtyckie or Bałtyk), Bulgarian (Baltijsko More (Балтийско море)), Kashubian (Bôłt), and Russian (Baltiyskoye Morye (Балтийское море)); and in the Baltic languages Latvian (Baltijas jūra) and Lithuanian (Baltijos jūra).

Notes

^ (sv) [1] (in Swedish).

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Geophysical data

The Baltic Sea is a brackish inland sea, the largest body of brackish water in the world. The fact that it does not come from the collision of plates, but is a glacially scoured river valley, accounts for its relative shallowness.

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Dimensions

The Baltic sea is about 1610 km (1000 mi) long, an average of 193 km (120 mi) wide, and an average of 55 m (180 ft, 30 fathoms) deep. The maximum depth is 459 m (1506 ft, 251 fathoms), on the Swedish side of the center. The surface area is about 377,000 sq km (145,522 sq mi) and the volume is about 21,000 cubic km (3129 cubic mi). The periphery amounts to about 8000 km (4968 mi) of coastline. [2] These figures are somewhat variable because a number of different estimates have been made.

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Icing in winter

On average, the Baltic Sea is iced in winter for roughly half of its surface area. The ice-covered area includes Gulf of Bothnia, Gulf of Finland, Gulf of Riga and Vainameri in Estonian archipelago. The Baltic proper, or Central Baltic Sea, does not normally freeze at all with the exception of sheltered bays and shallow lagoons (such as the Courland Lagoon). The ice reaches a maximum extent in February or March.

Icing begins in the northern coast of Gulf of Bothnia typically in early November, reaching the open waters of Bothnian Bay, the northern basin of Gulf of Bothnia, in early January. Bothnian Sea, the basin south of it, is frozen on average in late February. Gulf of Finland and Gulf of Riga freeze typically in late January.

The degree of icing depends on whether the winter is mild, moderate or severe. Severe winters ice even the regions around Denmark and southern Sweden, and on rare cases the whole sea is frozen, such as in 1942. More recently in 1987, some 96 % of Baltic Sea was iced, leaving only a small patch of open water to the west of Bornholm. Contrary to this, in milder winters it may happen that Bothnian Bay is the only larger area iced, in addition to coastal fringes in more southerly locations. From late 1980's onwards this has actually been quite usual, happening on average every fifth winter or so.

In spring, Gulf of Finland and Bothnian Sea thaw normally during late April, with some ice ridges persisting until May in eastern Gulf of Finland. In Bothnian Bay ice usually stays until late May; by early June it is practically always gone.

During winter fast ice, attached to the shoreline, develops first, rendering the ports unusable without the services of icebreakers. Level ice, ice sludge, pancake ice or rafter ice form in the more open regions. The gleaming expanse of ice is similar to the arctic, with wind-driven pack ice and ridges up to 15 m, and was noted by the ancients. During average winters, by February, the ice pack becomes fairly compact and stable in Bothnian Bay, Gulf of Finland and Gulf of Riga. However, on the larger expanse of Bothnian Sea there rarily exists very long periods of total icing; winds and periods of milder weather frequently crush the ice along coastlines or even melt it. In milder winters this is also true in the other regions.

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Hydrography

The Baltic Sea is effluent through the Danish straits; however, the flow is complex. A surface layer of brackish water discharges 940 cubic km per year into the North Sea. Due to the difference in salinity, a sub-surface layer of more saline water moving in the opposite direction brings in 475 cubic km per year. It mixes very slowly with the upper waters, resulting in a salinity gradient from top to bottom, with most of the salt water remaining below 40 to 70 m of depth.

The difference between the outflow and the inflow comes entirely from fresh water. More than 250 streams drain a basin of about 1.6 million square km, contributing a volume of 660 cubic km per year to the Baltic. They include the major rivers of north Europe, such as the Oder, the Vistula, the Neman and the Neva. Some of this water is polluted. Additional fresh water comes from the difference of precipitation less evaporation, which is positive.

Despite the influx of salt water in the lower levels, the Baltic is still more of a lake or river than a sea. Tides are negligible. Wave height in calm weather varies between 2 and 3 m. Violent and sudden storms often sweep the surface, due to large transient temperature differences and a long reach of wind.

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Salinity

Salinity is much lower than in the ocean, varying from 0.1 percent in the north to 0.6-0.8 percent in the center. Below 40-70 m, it can be as much as 1.5-2.0 percent. A lateral salinity gradient also exists from most saline in the northern Kattegat to least saline in the Northern Gulf of Bothnia.

The most saline water remains on the bottom, creating a barrier to the exchange of Oxygen and nutrients, fostering totally different maritime environments.

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Regional emergence

The land is still emerging from its subsident state, which was caused by the weight of the last glaciation. Consequently, the surface area and the depth of the sea are diminishing. The uplift is about eight millimetres per year on the Finnish coast of the northernmost Gulf of Bothnia .

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Geographic data

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Subdivisions

The northern part of the Baltic Sea is known as the Gulf of Bothnia out of which the northernmost part is referred to as the Bay of Bothnia or Bothnian Bay. The more roundish southern basin of the gulf is called Bothnian Sea and immediately to the south of it lies the Sea of Åland. The Gulf of Finland connects the Baltic Sea with St. Petersburg. The Gulf of Riga lies between the Latvian capital city of Riga and the Estonian island of Saaremaa.

The Northern Baltic Sea lies between the Stockholm area, southwestern Finland, and Estonia. The Western and Eastern Gotland Basins form the major parts of the Central Baltic Sea or Baltic proper. Bornholm Basin is the area east of Bornholm and Arkona Basin extends from Bornholm to the Danish isles of Falster and Zealand.

In south, Bay of Gdańsk lies east of the Hel peninsula on the Polish coast and west of Sambia in Kaliningrad Oblast. Bay of Pomerania lies north of the islands of Usedom and Wolin, east of Rügen. Between Falster and the German coast lie the Bay of Mecklenburg and Bay of Lübeck. The westernmost part of the Baltic Sea is the Bay of Kiel. The three Danish straits, the Great Belt, the Little Belt and The Sound (Öresund) connect the Baltic Sea with the Kattegat bay and Skagerrak strait in the North Sea. The confluence of these two seas at Skagen on the northern tip of Denmark is a visual spectacle visited by many tourists each year.

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Land use

The Baltic sea drainage basin is roughly four times the surface area of the sea itself. About 48% of the region is forested, with Sweden and Finland containing the majority of the forest, especially around the Gulfs of Bothnia and Finland.

About 20% of the land is used for agriculture and pasture, mainly in Poland and around the edge of the Baltic sea proper, in Germany, Denmark and Sweden. About 17% of the basin is unused open land with another 8% of wetlands. Most of the latter are in the Gulfs of Bothnia and Finland.

The rest of the land is heavily populated.

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Demographics

About 85 million people live in the Baltic drainage basin, 15 within 10 km of the coast and 29 within 50 km of the coast. Around 22 million live in cities, defined as centers of over 250,000. 90% of these are concentrated in the 10 km band around the coast. Of the nations containing all or part of the basin, Poland includes 45% of the 85 million, Russia 12%, Sweden 10% and the others (see below) less than 6% each.

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Geologic history

The Baltic Sea somewhat resembles a riverbed, with two tributaries (the Gulf of Finland and Gulf of Bothnia). From geological surveys it has become apparent that there was a river in the area prior to the Pleistocene: the Eridanos. Multiple glaciations in the Pleistocene scooped out the river bed into the sea basin. By the time of the last, or Eemian interglacial (MIS 5e), the Eemian sea was in place.

From that time the waters underwent a geologic history summarized under the names listed below. Many of the stages are named after certain marine animals (e. g., the Littorina mollusk) that are clear markers of changing water temperatures and salinity.

The factors that determined the sea’s characteristics were the submergence or emergence of the region due to the weight of ice and subsequent isostatic readjustment, and the connecting channels it could find to the North Sea-Atlantic either through the straits of Denmark or at what are now the large lakes of Sweden, and the White Sea-Arctic Sea.

Eemian sea, 130,000-115,000 BP
Baltic ice lake, 12,600-10,300 BP
Yoldian sea, 10,300-9500 BP
Ancylus lake, 9500-8000 BP
Mastogloia sea 8000 BP-7500 BP
Littorina sea, 7500-4000 BP
Post-littorina sea 4000 BP-current

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Prehistory

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History

At the time of the Roman Empire, the Baltic Sea was known as the Mare Suebicum or Mare Sarmaticum. Tacitus in his AD 98 Agricola and Germania described the Mare Suebicum, named for the Suebi tribe, during the spring months, as a brackish sea when the ice on the Baltic Sea broke apart and chunks floated about. The Sarmatian tribes inhabited Eastern Europe and southern Russia. Jordanes called it the Germanic Sea in his work the Getica.

Since the Viking age, the Scandinavians have called it "the Eastern Lake" (Austmarr, "Eastern Sea", appears in the Heimskringla and Eystra salt appears in Sörla þáttr), but Saxo Grammaticus recorded in Gesta Danorum an older name Gandvik, "-vik" being Old Norse for "bay", which implies that the Vikings correctly regarded it as an inlet of the sea. (Another form of the name, "Grandvik", attested in at least one English translation of Gesta Danorum, is likely to be a misspelling.)

In addition to fish the sea also provides amber, especially from its southern shores. The bordering countries have traditionally provided lumber, wood tar, flax, hemp, and furs. Sweden had from early medieval times also a flourishing mining industry, especially on iron ore and silver. Poland had and still has extensive salt mines. All this has provided for rich trading since the Roman times.

In the early Middle Ages, Vikings of Scandinavia fought for power over the sea with Slavic Pomeranians. The Vikings used the rivers of Russia for trade routes, finding their way eventually all the way to Black Sea and southern Russia.

Lands next to the sea's eastern shore were among the last in Europe to be converted into Christianity in the Northern Crusades: Finland in the 12th century by the Swedes, and what are now Estonia and Latvia in the early 13th century by the Danes and the Germans (Livonian Brothers of the Sword). The powerful German Teutonic Knights gained control over most of the southern and eastern shore of the Baltic Sea, while fighting the Poles, the Danes, the Swedes, the Russians of ancient Novgorod, and the Lithuanians (latest of all Europeans to convert to Christianity).

Later on, the strongest economic force in Northern Europe became the Hanseatic league, which used the Baltic Sea to establish trade routes between its member cities. In the 16th and early 17th centuries, Poland, Denmark and Sweden fought wars for Dominium Maris Baltici (Ruling over the Baltic Sea). Eventually, it was the Swedish empire that virtually encompassed the Baltic Sea. In Sweden the sea was then referred to as Mare Nostrum Balticum (Our Baltic Sea).

In the 18th century Russia and Prussia became the leading powers over the sea. Russia's Peter the Great saw the strategic importance of the Baltic and decided to found his new capital, Saint Petersburg at the mouth of the Neva river at the east end of the Gulf of Finland. There was much trading not just within the Baltic region but also with the North Sea region, especially the eastern England and the Netherlands: their fleets needed the Baltic timber, tar, flax and hemp.

During the Crimean War a joint fleet of Britain and France attacked Russian fortresses by bombarding Sveaborg that guards Helsinki and Kronstadt that guards Saint Petersburg and destroying Bomarsund in the Åland Islands. After the unification of Germany in 1871, the whole southern coast became German. The First World War was fought also on the Baltic Sea. After 1920 Poland returned to the Baltic Sea, and Polish ports of Gdynia and Gdańsk became leading ports of the Baltic.

During the Second World War Germany reclaimed all of the southern shore and much of the eastern by occupying Poland and the Baltic states. In 1945 the Baltic Sea became a mass grave for drowned people on torpedoed refugee ships. As of 2004, the sinking of the Wilhelm Gustloff remains the worst maritime disaster of all time, killing (very roughly) 9,000 people. In 2005, a Russian group of scientists found over 5,000 airplane wrecks, sunken warships, etc., (mainly from the Second World War) lying in the bottom of the sea.

After 1945 the sea was a border between conflicted military blocks: in case of military conflict in Germany, in parallel with a Soviet offensive towards the Atlantic Ocean, communist Poland's fleet was prepared to invade Danish isles.

In May 2004, the Baltic Sea became almost completely a European Union internal sea when the Baltic states and Poland became parts of the European Union, leaving only the Russian metropolis of Saint Petersburg and the exclave of Kaliningrad Oblast as non-EU areas.

The Baltic Sea starts to get very rough with the October storms. These winter storms have been the cause of many shipwrecks, for example, the sinking of the ferry M/S Estonia en route from Tallinn, Estonia to Stockholm, Sweden in 1994 that claimed the lives of hundreds. But thanks to the cold brackish water where the shipworm cannot survive, the sea is a time capsule for centuries-old shipwrecks. Perhaps the most famous one is the Vasa.

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Biology

Image:Phytoplankton bloom in the Baltic Sea (July 3, 2001).jpg

Approximately 100,000 square km of the seafloor (¼ of the total area) is a variable dead zone. The more saline (and therefore denser) water remains on the bottom, isolating it from surface waters and the atmosphere. This leads to decreased oxygen concentrations within the zone. It is mainly bacteria that grow in it, digesting organic material and releasing hydrogen sulfide. Because of this large anaerobic zone, the seafloor ecology differs from that of the neighbouring Atlantic.

The low salinity of the Baltic sea has led to the evolution of many slightly divergent species, such as the Baltic Sea herring, which is a smaller variant of the Atlantic herring. The benthic fauna consists mainly of Monoporeia affinis, which is originally a freshwater species. The lack of tides has affected the marine species as compared with the Atlantic.

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Economy

Construction of the Great Belt Bridge (1997) and Oresund Bridge (1999) over the international waterway of the Danish Straits limited the Baltic Sea to the middle-sized vessels. In meantime, the Baltic Sea is the main trade route for export of Russian oil. Many of the neighboring countries are rather concerned about this, since a major oil leak would be disastrous in the Baltic given the slow exchange of water, and the many unique species. The tourism industries, especially in economies dependent on tourism like for example in northeastern Germany, are naturally very concerned.

Shipbuilding is practiced in many large shipyards around the Baltic: Gdańsk, Szczecin in Poland, HDW in Kiel, Germany, Karlskrona and Kockums in Malmö, Sweden, and Rauma, Turku, Helsinki in Finland and Klaipėda in Lithuania.

There are several cargo and passenger ferry operators on the Baltic Sea, such as Silja Line, Polferries, Viking Line, Tallink and Superfastferries.

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