Why is winter in Tromsø, Norway, located above the Arctic Circle, warmer than in Kyiv, which lies much further south?
What is a current
A current is the horizontal movement of water in the ocean. Ocean currents resemble huge rivers within the water column, but unlike rivers, currents have no clear boundaries. They consist of individual streams whose speed is constantly changing.
The main causes of their formation are persistent winds and the daily rotation of the Earth on its axis.
All currents can be divided into two large groups: cold and warm. One of the largest currents, which has a tremendous influence on shaping our planet’s climate, is the warm Gulf Stream current.
What is the Gulf Stream
The Gulf Stream is a current that flows along the eastern shores of North America from the Florida Strait to the island of Newfoundland.
It was discovered by the Spanish conquistador Juan Ponce de León in 1513. While sailing between the Bahamas and Florida, the navigator got caught in the Gulf Stream, which pushed the ships back.
However, the Gulf Stream was only studied in detail in 1770. This was done by the American public figure Benjamin Franklin, who at the time was Deputy Postmaster General of the British colonies. He noticed that ships returning from the New World arrived back much faster. It was he who gave this huge river in the ocean its name: gulf stream — meaning “the current from the gulf.”
The Gulf Stream has a width of 70 to 90 km. Its maximum speed ranges from several meters per second in surface waters to 10–20 cm per second at a depth of about 1000 m. The most important indicator is the temperature: on the surface it is +25…+26 °C, at a depth of 400 m it reaches +10…+12 °C.
How the Gulf Stream works
The Gulf Stream originates in the Florida Strait, where the warm flows of the Florida and Antilles Currents meet. It then carries warm waters from the Gulf of Mexico northward into the Atlantic.
Around the 38th parallel of the Northern Hemisphere, it turns east. This occurs as a result of its meeting with the cold Labrador Current, which deflects the Gulf Stream towards the shores of Europe, as well as due to the Coriolis force, which arises from the Earth’s rotation and deflects all moving objects to the right.
Further on, the current branches out, forming a kind of delta. Its main branch — the North Atlantic Current — diverts waters, already slightly cooled on the long journey, to the northeast, towards the Scandinavian Peninsula. Upon reaching the shores of Greenland, the warm waters finally cool down. Becoming heavier and denser, they sink downward, where a countercurrent arises, carrying the water flow south. The circle closes.
The remaining branches flow towards the Iberian Peninsula and also turn south there, where, off the coast of Africa, they meet the North Equatorial Current, heading towards the Sargasso Sea. Therefore, if you consider the length of the Gulf Stream with all its branches, it amounts to approximately 10,000 km.
How the Gulf Stream affects nature and humans
The current is not called “Europe’s warm stove” for nothing. It heats the air above the water’s surface, and winds carry this air to the European shores. Therefore, the temperature there is approximately 12 °C higher than in other regions of the world at the same latitudes.
Thus, the average annual temperature in London is +12 °C, while in Kyiv it is about +8 °C. The average January temperature in Kyiv is -3.5 °C, but in the Scottish port city of Glasgow, located at the same latitude, it reaches +3.5 °C. The Lofoten Islands are situated near the Arctic Circle, but thanks to the Gulf Stream, the average air temperature there is the same as on the Crimean Peninsula.
As a result, residential buildings in Western and Northern Europe do not require such powerful insulation as in Ukraine, which saves fuel resources. And thanks to the absence of sharp temperature fluctuations, asphalt pavement lasts longer.
Warmer water also affects the fauna of the Atlantic Ocean. Heat-loving fish species, such as mackerel, migrate much further north than in other parts of the World Ocean. This has a positive effect on the development of the fishing industry.
What will happen if the Gulf Stream stops
Over the past decades, the Gulf Stream has been warming, with the water temperature increasing by about 1 °C. Along with this, the speed of the current is decreasing, and the warm water flow is shifting closer to the shores of North America.
According to research published in the journal Nature Communications, the Atlantic Ocean current system, of which the Gulf Stream is a part, could reach a critical tipping point as early as the middle of this century if global carbon emissions are not reduced. The cause: global warming, which leads to the melting of glaciers and, consequently, an increase in the amount of fresh water in the World Ocean.
This will lead to equatorial regions becoming hotter and drier, while the northern part, on the contrary, will get significantly colder. Winter will become long and harsh, and summer — rainy, short, and cool. The change in atmospheric pressure will lead to stronger winds. Storms will become more frequent, especially in North America. Climatic changes will cause the migration of fish and other marine organisms. A similar phenomenon already occurred in 1312, when a slowdown of the Gulf Stream caused a Little Ice Age in the world, and a quarter of Europe’s population died from cold and famine caused by crop failure.
Serious changes will also affect Eastern Europe. The disappearance of the warming influence of the Atlantic will lead to significant cooling, and cold Arctic air masses will break through to the south more often. This will cause harsher winters and a general shift of climatic zones, which will negatively impact the region’s agriculture.
Interesting facts about the Gulf Stream
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The waters of the current are bright blue due to a higher concentration of salt — sharply differing from the gray or greenish waters of the ocean.
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The Gulf Stream is more powerful than the largest river in the world — the Amazon — by 300 times. The thermal power of the current equals the thermal power of one million modern nuclear power plants.
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Norwegian ports such as Tromsø and Hammerfest, located far beyond the Arctic Circle, do not freeze in winter thanks to the Norwegian Current, which is a direct continuation of the Gulf Stream.
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Meeting the cold Labrador Current off the coast of the island of Newfoundland, the Gulf Stream makes this place the foggiest on Earth.
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As a result of the interaction between warm water and the cold air above it, unusual optical phenomena are formed over the current: green flashes and mirages.
