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Chantel Loura //

Defining the Arctic

Exploring Arctic region by expedition cruising

Where Are the Boundaries of the Arctic?

For most of us, the Arctic is defined by our imaginations. We think of the Arctic as being cold, remote and sparsely populated. We imagine endless summer days and long polar winters. We think of a region full of ice and devoid of trees, home to polar bears, walrus and reindeer (and sometimes penguins, though this would be wrong). These are the classic ideas we have about the Arctic. But how precisely do we define the Arctic? Where are its actual boundaries? As it turns out, this vast and varied region does not fit neatly into a cartographer’s lines. Read on to learn about the various definitions of the Arctic that have been proposed.


Land of the Midnight Sun

The Arctic Circle is a line drawn around the top of the globe, at 66°33′47.5″ north latitude, encircling 7.7 million square miles (20 million square km) of Earth’s surface. All of this area can be called the Land of the Midnight Sun. At any point on the Arctic Circle itself, the sun is above the horizon all day on the summer solstice, even at midnight. As you go north—farther inside the circle—the uninterrupted polar day becomes increasingly longer until you reach the North Pole, where the sun does not set for six months. Despite long summer days, the low angle of the sun’s light causes the climate to be cold in these northern latitudes. In this way, the Arctic Circle makes an attractive boundary for the Arctic region.

However, not all places within the Arctic Circle fit our common ideas of the Arctic. Due to the effects of ocean currents, some areas north of the Arctic Circle (e.g. northern Norway) have climates mild enough for forests and agriculture. Other places within the circle (e.g. northeast Russia) are highly industrialized and very populated. Likewise, some lands south of the Arctic Circle (e.g. southern Greenland) are quite cold, barren and unpopulated. Hudson Bay, also south of the circle, even has polar bears. So, while convenient, the Arctic Circle is not a perfect delimitation of the Arctic that exists in our imaginations.

Beyond the Arctic Circle

Sea Ice and Tree Line

Sea ice is an important real and imagined characteristic of the Arctic. As such, another proposed Arctic boundary is the southern limit of sea ice. It must be noted, however, that such a boundary is subject to seasonal variations and yearly fluctuations, especially now when the Arctic is warming rapidly due to climate change. Also, it is not exactly clear how we should interpolate the sea ice limit across the continents that surround the Arctic Ocean. One possibility for the Arctic land boundary would be the tree line, north of which tall trees cannot grow for various reasons. This is an attractive possibility because the areas north of this line contain the classic Arctic landscapes of tundra and polar desert. On maps, this line looks smooth and solid. However, on the ground, the tree line is not a clear or easily defined boundary. It is a vague transitional zone as much as 125 miles (200 km) wide with islands of trees to the north and patches of treeless tundra to the south, making it not nearly as precise as the Arctic Circle. Still, the Arctic as defined by sea ice and tree line is a better representation of the Arctic in our imaginations.

Summer Isotherm

To resolve the problems of the above definitions, climatologists have proposed a temperature-based boundary known as the summer 50°F (10°C) isotherm. This is the line connecting points on the Earth’s surface where the mean temperature of the warmest month is 50°F (10°C). In this way, the Arctic region can be defined as the northern area where the average July temperature is below 50°F (10°C). As temperature is easily measured and closely tied to the ecology of a region, this is regarded as a logical solution and is the most popular definition of the Arctic. Though, it too has its limitations, particularly the fact that the isotherm is poorly defined across intercontinental water bodies. Also, it does not account for the fact that the areas with the coldest winter temperatures in the northern hemisphere (some inland areas of Siberia) are actually located south of this line.

Ultimately, no academic definition of the Arctic can perfectly capture the many ways in which the Arctic captures our imagination. Luckily, you can turn your imagination into reality with an Arctic expedition cruise. The remote, icy, sparsely populated and wildlife-rich regions of Svalbard, Franz Josef Land, Greenland, and the North Pole will surely meet all expectations of a true Arctic wilderness. For a journey across all the various boundaries of the Arctic, take a cruise from Scotland to Svalbard. You will cross the Arctic Circle and the 50°F (10°C) summer isotherm on your way to meet polar bears on sea ice and treeless tundra. Whatever ideas you have of the Arctic, turn them into experiences and lifelong memories with Poseidon Expeditions!

Walrus encounters in Arctic cruises


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