The Arctic is the northernmost region of Earth. 
 
Most scientists define the Arctic as the area within the Arctic Circle, a line of latitude about 66.5° north of the Equator. Within this circle are the Arctic ocean basin and the northern parts of Scandinavia, Russia, Canada, Greenland, and the U.S. state of Alaska.
 
The Arctic is almost entirely covered by water, much of it frozen. Some frozen features, such as glaciers and icebergs, are frozen freshwater. In fact, the glaciers and icebergs in the Arctic make up about 20% of Earth’s supply of freshwater.
 
Most of the Arctic, however, is the liquid saltwater of the Arctic ocean basin. Some parts of the ocean’s surface remain frozen all or most of the year. This frozen seawater is called sea ice. Often, sea ice is covered with a thick blanket of snow.
 
Sea ice helps determine Earth’s climate. Sea ice has a very bright surface, or albedo. This albedo means about 80% of sunlight that strikes sea ice is reflected back to space. The dark surface of the liquid ocean, however, absorbs about 90% of solar radiation. Due to thermohaline circulation, the Arctic’s thick, reflective sea ice moderates ocean temperatures around the world.
 
The Arctic experiences the extremes of solar radiation. During the Northern Hemisphere’s winter months, the Arctic is one of the coldest and darkest places on Earth. Following sunset on the September equinox, the Earth’s tilted axis and its revolution around the sun reduce the light and heat reaching the Arctic until no sunlight penetrates the darkness at all. 
 
The sun rises again during the March equinox, and increases the light and heat reaching the Arctic. By the June solstice, the Arctic experiences 24-hour sunshine.
 
Life in the Arctic
 
Marine Ecosystem
The Arctic ocean basin is the shallowest of the five ocean basins on Earth. It is also the least salty, due to low evaporation and huge influxes of freshwater from rivers and glaciers.
 
River mouths, calving glaciers, and constantly moving ocean currents contribute to a vibrant marine ecosystem in the Arctic. The cold, circulating water is rich in nutrients, as well as the microscopic organisms (such as phytoplankton and algae) that need them to grow. 
 
Marine animals thrive in the Arctic. Primary consumers such as jellies and shrimp consume plankton, the basis of the Arctic marine food web
 
Secondary consumers include fish, seabirds (such as gulls and puffins), and a wide variety of baleen whales, including giant blue whales and bowhead whales. 
 
Tertiary consumers, animals that prey mostly on other carnivores, include toothed whales and dolphins (such as orcas and narwhals) and pinnipeds such as seals, sea lions, and walruses. 
 
Scavengers (including some sharks and crabs) and decomposers such as marine worms and algae break down dead and decaying materials. Organic nutrients are thus recycled into the marine ecosystem of the Arctic.
 
Terrestrial Ecosystems
The varied landscapes of the Arctic provide for a variety of ecosystems. The Arctic includes the peaks of the Brooks mountain range in western North America, the enormous Greenland ice sheet, the isolated islands of the Svalbard archipelago, the fjords of northern Scandinavia, and the grassland plateaus and rich river valleys of northern Siberia.
 
Although some forests lie near the Arctic Circle, plant life is mostly limited to grasses, sedges, and tundra vegetation such as mosses and lichens. These autotrophs have the ability to survive despite being covered in snow and ice for much of the year. 
 
Insects such as mosquitoes and moths are common, especially as icemelt creates ponds during spring and summer. Insects and insect larvae provide a crucial diet for birds, such as wrens and sandpipers, and freshwater fish.
 
Primary consumers across the region range from tiny lemmings to enormous muskoxen. One of the most familiar Arctic herbivores is the caribou, often known as the reindeer in Europe and Asia.
 
Secondary consumers include Arctic foxes, and raptors such as owls and eagles. The polar bear, the iconic apex predator of the Arctic, is equally able to hunt on land and around ice floes.
 
Like the polar bear, many other animals of the Arctic are white: beluga whales, snowy owls, juvenile harp seals. This coloring helps camouflage them in heavy snow and ice. 
 
Many Arctic animals even change their coloration seasonally. Species of Arctic fox and Arctic hare, for example, are snowy white in winter but molt and grow a brownish or greyish fur coat during the summer months. Even fluffy white baby seals will ultimately grow up to a dark brown—better to blend in with the dark Arctic ocean waters instead of blinding white ice floes.
 
People in the Arctic
 
Indigenous Cultures
People established communities and cultures in the Arctic thousands of years ago, and continue to thrive today. They have all developed smart, innovative ways to adapt to the unique challenges posed by the region’s severe climate.
 
Housing or other shelter, for example, poses unusual challenges for Arctic peoples. Thick blankets of seasonal snow and lack of abundant trees for lumber historically limited the development of wood or stone structures common in subarctic climates.
 
Inuit bands in Canada and Greenland, for example, engineered “snow houses”—more commonly known as igloos. Igloos were circular structures made of stacked ice (often sea ice), insulated with snow. The rectangular blocks were stacked in tight spiral pattern, giving the igloo a domed shape. Igloos could hold as few as two and as many as 20 people.
 
Igloos were just one type of Inuit dwelling. Inuit communities also built tents with poles crafted from driftwood and whale bones or baleen. Animal hides covered these poles, and snow provided excellent insulation.
 
The historically nomadic Sami (an indigenous people of Scandinavia and northwestern Russia) also built temporary tent-like structures, called lavvu. Instead of relying on driftwood, however, Sami communities had access to the rich taiga, or boreal forests, of the European subarctic.
 
More permanent Sami structures included storehouses, where foods, textiles, and other valuables could be stored for later use or trade. These storehouses, which resemble log cabins, are notable for being elevated on stilts, centimeters or even meters from the ground. Elevation protected the valuables from excess rot due to snow or water seeping into the storehouse, as well as vermin such as mice or rats.
 
Today, Arctic cultures such as the Inuit and Sami have access to high-quality building materials and sophisticated structural engineering plans. Still, buildings throughout the Arctic are reliant on efficient insulation and weatherization. (Weatherization is the process of protecting a dwelling from extreme temperature changes, precipitation, and wind.)
 
Challenges of Indigenous Cultures
Rights to land and natural resources are an important part of contemporary culture and survival of indigenous peoples in the Arctic. Indigenous Arctic communities face tremendous challenges, often the result of colonization and exploitation of land and energy resources.
 
For hundreds of years, for instance, European and Asian explorers interacted with Inuit communities in the Canadian Arctic, searching for the North Pole and the elusive “Northwest Passage.” (The Northwest Passage is a sea route connecting the North Pacific and North Atlantic ocean basins.)
 
Increased contact with Europeans and European Americans often came with conflict. Inuit social structure, schools, and language were replaced with Western traditions.
 
Starting in the late 20th century, regional, national, and international organizations increasingly recognized the political and cultural sovereignty of Arctic peoples. Rights to land and natural resources are an important part of this sovereignty. 
 
An agreement between the government of Canada and Inuit bands, for instance, ultimately resulted in the creation of the territory of Nunavut in 1999. Nunavut, Canada’s largest territory, stretches far into the central Canadian Arctic. More than half the population of Nunavut identifies as Inuit, and Inuktitut is the most-spoken language. 
 
Exploration
European and Asian exploration of the Arctic began with Viking settlement of northern Scandinavia and Iceland in the 900s. Russian explorers navigated the “Northern Sea Route” of the Northeast Passage and the Siberian Arctic, eventually crossing the Bering Strait in the 1600s.
 
The pursuit of the Northwest Passage, which would save untold time and money in trade between Europe and Asia, drove Arctic exploration during the Age of Discovery. Explorers such as John Cabot, Martin Frobisher, and Henry Hudson all failed to find an open-water route. The Northwest Passage was not completely navigated until 1906, when legendary Norwegian explorer Roald Amundsen and his crew made the voyage from Greenland to Alaska. Shifting sea ice made the trip hazardous; it took about three years, and required a relatively small ship (a converted fishing vessel).
 
Resources in the Arctic
 
The Arctic has enormous deposits of oil and natural gas. In Alaska, many oil companies work with indigenous groups known as “native corporations” to drill and export millions of barrels of oil every year. Alaska’s North Slope contains 6% of the largest oil fields in the United States and one of the 100 largest natural gas fields.
 
Engineers and geographers estimate that oil and gas deposits in the Arctic make up 13% of the world’s undiscovered petroleum resources, and 30% of undiscovered natural gas resources.
 
The Arctic is also rich in minerals, such as nickel and copper ore. Mineral resources also include gemstones and rare earth elements, which are used in batteries, magnets, and scanners. Some of these mineral deposits are underground, while others are buried beneath the Arctic Ocean. 
 
Mines and drilling operations are often dependent on the weather. In the winter, machinery can freeze, and the frozen ground becomes too hard to drill. In warmer weather, the Arctic permafrost can thaw and machinery can become unstable and damage the environment.
 
Race for the Arctic
Almost all Arctic nations are scrambling to assert authority over the rich resources of the Arctic. This diplomatic conflict has been nicknamed the “New Cold War” or simply the “Race for the Arctic.”
 
The exclusive economic zones of Russia, Norway, Denmark, Iceland, Greenland, Canada, and the United States extend to 200 nautical miles off their coasts. A country can explore and exploit all resources within its exclusive economic zone (EEZ)
 
However, some Arctic nations are claiming territory on their continental shelves, not just their coastlines. Russia, Greenland, Denmark, and Canada, for instance, all claim the Lomonosov Ridge. The Lomonosov Ridge is an undersea mountain chain that stretches from the Canadian Arctic, through the North Pole, all the way to the waters off Siberia.
 
Changing Climate in the Arctic
 
Climate change is radically redefining the geography, biodiversity, and political units of the Arctic. 
 
The extent of sea ice in the Arctic is shrinking. The 21st century has marked record lows in both the winter maximum and summer minimum extent of sea ice. Most climatologists estimate that by the year 2100, most Arctic sea ice will melt every summer. 
 
The “twilight of the Arctic ice” would devastate many habitats. The plight of polar bears, for example, has become a symbol of global warming in the Arctic due to the cascading impacts of sea ice loss.
 
Without sea ice, polar bears cannot catch enough seals to survive their annual winter fast. Polar bears that do survive are less likely to produce healthy offspring, reducing the population over generations. Scarcer food sources also drive polar bears into more contact with human populations, often relying on trash heaps for nutrition. This food sources impacts the health of polar bears and increases the incidents of conflict with human communities in the Arctic.
 
The species range of the polar bear is also altered by climate change. Logic might indicate that polar bears would migrate further north as their traditional range heats up. Currents carry sea ice south, however, as it breaks up. Polar bears follow the sea ice habitat, and so their range has actually drifted south. This has brought polar bears into even closer contact with human populations, as well as prey species that have not adapted to the bears’ predatory behavior.
 
The increasingly shrinking Arctic sea ice provides clear shipping routes for trade and travel. The Northwest Passage is still the most lucrative shipping lane in the Arctic. Experts estimate that shipping time may be cut by 40% if the Northwest and Northeast passages were ice-free all year. These deep-water shipping lanes also allow for larger, heavier ships than the Panama Canal, which would increase trade and profit even further.
 
The tourism industry could also benefit from shrinking sea ice. In 2016, a luxury cruise ship traveled through the Northwest Passage for the first time. The ship, filled with more than 1,500 tourists, made the journey in three weeks.
Arctic
The Arctic is dominated by the Arctic ocean basin.
Balmy Arctic
The Arctic is mostly an ocean surrounded by land. The Antarctic is mostly land surrounded by water. Because the Arctic ocean absorbs so much more solar radiation than the Antarctic ice sheet, the Arctic is much, much, much warmer than the Antarctic. In fact, the Arctic is not even the coldest place in the Northern Hemisphere. (The icy, subarctic interior of Siberia, in eastern Russia, holds that record.)
Icebreakers
Travel in the Arctic is still dependent on icebreakers. An icebreaker is a very powerful ship capable of breaking up kilometers of sea ice, sometimes several meters thick. Icebreakers are most often powered by nuclear fuel, but can also run on gas and steam. They can be uncomfortable to travel in, as their shape allows them to roll back and forth more easily than other heavy ships. Russia manufactures the most powerful icebreakers.
Oil in ANWR 
The Arctic National Wildlife Refuge (ANWR), situated on Alaska’s northeastern coast, is the largest protected wilderness in the United States. Extractive activities are allowed in the refuge, as long as the U.S. Congress approves. Some geologists estimate that there may be between 5 billion and 16 billion barrels of oil and natural gas beneath the coastal plain of the refuge. People have debated since the 1970s about whether to develop this pristine area, but Congress has not given any approval to drill or mine there.
albedo
Noun

scientific measurement of the amount of sunlight that is reflected by a surface.

albedo
Noun

scientific measurement of the amount of sunlight that is reflected by a surface.

algae
Plural Noun

(singular: alga) diverse group of aquatic organisms, the largest of which are seaweeds.

apex predator
Noun

species at the top of the food chain, with no predators of its own. Also called an alpha predator or top predator.

Noun

a group of closely scattered islands in a large body of water.

Noun

region at Earth's extreme north, encompassed by the Arctic Circle.

Arctic Circle
Noun

paralell of latitude that runs 66.5 degrees north of the Equator.

assert
Verb
to state with confidence.
Noun

organism that can produce its own food and nutrients from chemicals in the atmosphere, usually through photosynthesis or chemosynthesis.

Noun

an invisible line around which an object spins.

baleen
noun, plural noun

flexible, horn-like substance hanging from the upper jaw of certain whales, used to strain plankton from seawater when feeding.

Noun

all the different kinds of living organisms within a given area.

boreal forest
Noun

land covered by evergreen trees in cool, northern latitudes. Also called taiga.

cabin
Noun

area in a vehicle where crew or passengers live.

camouflage
Verb

to hide or disguise by blending in to surroundings. Also called cryptic coloration.

Noun

organism that eats meat.

cascade
Verb
to fall downward quickly and in great quantity.
Noun

all weather conditions for a given location over a period of time.

Noun

gradual changes in all the interconnected weather elements on our planet.

climatologist
Noun

person who studies long-term patterns in weather.

colonize
Verb

to establish control of a foreign land and culture.

conflict
Noun

a disagreement or fight, usually over ideas or procedures.

contemporary
Adjective

having to do with the present time period.

Noun

part of a continent that extends underwater to the deep-ocean floor.

crucial
Adjective

very important.

culture
Noun

learned behavior of people, including their languages, belief systems, social structures, institutions, and material goods.

decay
Verb

to rot or decompose.

decomposer
Noun

organism that breaks down dead organic material.

devastate
Verb

to destroy.

Noun

foods eaten by a specific group of people or other organisms.

diplomatic
Adjective

skillful and respectful in dealing with people or communities.

driftwood
Noun

pieces of wood that have traveled on currents in a body of water and drifted on shore.

drill
Verb

to make a hole using a rotating digging tool.

elevate
Verb

to raise higher than the surrounding area.

elusive
Adjective

difficult to capture.

engineer
Noun

person who plans the building of things, such as structures (construction engineer) or substances (chemical engineer).

enormous
Adjective

very large.

Noun

imaginary line around the Earth, another planet, or star running east-west, 0 degrees latitude.

Noun

period in which daylight and darkness are nearly equal. There are two equinoxes a year.

Noun

process by which liquid water becomes water vapor.

exclusive economic zone (EEZ)
Noun

zone extending 200 nautical miles off a country's coast. A country has the right to explore and exploit the living and nonliving things in its EEZ.

exploit
Verb

to use or take advantage of for profit.

exploration
Noun

study and investigation of unknown places, concepts, or issues.

export
Noun

good or service traded to another area.

fast
Verb

to not eat.

Noun

long, narrow ocean inlet between steep slopes.

Noun

all related food chains in an ecosystem. Also called a food cycle.

forest
Noun

ecosystem filled with trees and underbrush.

freshwater
Noun

water that is not salty.

gem
Noun

mineral, rock, or organic material that can be cut and polished for use in jewelry.

generation
Noun

group in a species made up of members that are roughly the same age.

geographer
Noun

person who studies places and the relationships between people and their environments.

Noun

mass of ice that moves slowly over land.

Noun

increase in the average temperature of the Earth's air and oceans.

Noun

environment where an organism lives throughout the year or for shorter periods of time.

hazard
Noun

danger or risk.

Noun

organism that eats mainly plants and other producers.

hide
Noun

leather skin of an animal.

Noun

large chunks of ice that break off from glaciers and float in the ocean.

ice floe
Noun

floating chunk of frozen water less than 10 kilometers (6.2 miles) wide.

Noun

thick layer of glacial ice that covers a large area of land.

iconic
Adjective

event or symbol representing a belief, nation, or community.

igloo
Noun
dome-shaped hut built of blocks of ice. Also called an ice house.
incident
Noun

event or happening.

indicate
Verb

to display or show.

indigenous people
Noun

ethnic group that has lived in the same region for all of their known history.

influx
Noun

entry or inflow.

innovative
Adjective

new, advanced, or original.

insulate
Verb

to cover with material to prevent the escape of energy (such as heat) or sound.

Noun

unit made up of governments or groups in different countries, usually for a specific purpose.

Noun

body of land surrounded by water.

isolate
Verb

to set one thing or organism apart from others.

Noun

the geographic features of a region.

Noun

distance north or south of the Equator, measured in degrees.

lichen
Noun

organism composed of a fungus or fungi and an alga or cyanobacterium.

lucrative
Adjective

profitable or money-making.

lumber
Noun

precisely cut pieces of wood such as boards or planks.

luxury
Noun

expensive item.

machinery
Noun

mechanical appliances or tools used in manufacturing.

marine ecosystem
Noun

community of living and nonliving things in the ocean.

microscopic
Adjective

very small.

migrate
Verb

to move from one place or activity to another.

mine
Verb

to extract minerals from the Earth.

mineral
Noun

inorganic material that has a characteristic chemical composition and specific crystal structure.

molt
Verb

to shed fur, skin, feathers, or other body covering.

moss
Noun

tiny plant usually found in moist, shady areas.

mountain range
Noun

series or chain of mountains that are close together.

Noun

place where a river empties its water. Usually rivers enter another body of water at their mouths.

native corporations
Noun

business organizations concerned with economic decisions for a region of Alaska in which native Alaskans own all the stock. Also called ANCSA corporations, after the 1971 law that created these units, the Alaska Native Claims Settlement Act.

Noun

type of fossil fuel made up mostly of the gas methane.

natural resource
Noun

a material that humans take from the natural environment to survive, to satisfy their needs, or to trade with others.

navigate
Verb

to plan and direct the course of a journey.

nomadic
Adjective

having to do with a way of life lacking permanent settlement.

Northern Hemisphere
Noun

half of the Earth between the North Pole and the Equator.

Noun

fixed point that, along with the South Pole, forms the axis on which the Earth spins.

Northwest Passage
Noun

waterway connecting the Atlantic and Pacific Oceans.

Noun

substance an organism needs for energy, growth, and life.

nutrition
Noun

process by which living organisms obtain food or nutrients, and use it for growth.

ocean basin
Noun

depression in the Earth's surface located entirely beneath the ocean.

ocean current
Noun

continuous, predictable, directional movement of seawater.

offspring
Noun

the children of a person or animal.

oil
Noun

fossil fuel formed from the remains of marine plants and animals. Also known as petroleum or crude oil.

oil barrel
Noun

unit of measurement for oil and other petroleum products in the United States equal to 159 liters or 42 gallons. Abbreviated bbl.

Noun

deposit in the Earth of minerals containing valuable metal.

organism
Noun

living or once-living thing.

Noun

piece of land jutting into a body of water.

Noun

permanently frozen layer of the Earth's surface.

Noun

fossil fuel formed from the remains of ancient organisms. Also called crude oil.

phytoplankton
Noun

microscopic organism that lives in the ocean and can convert light energy to chemical energy through photosynthesis.

pinniped
Noun

marine mammals that also live on land and have flippers, such as seals.

Noun

large region that is higher than the surrounding area and relatively flat.

Noun

all forms in which water falls to Earth from the atmosphere.

predatory
Adjective

killing other animals for food.

prey
Verb

to target, victimize, or devour.

primary consumer
Noun

organism that eats plants or other autotrophs.

profit
Noun

money earned after production costs and taxes are subtracted.

pursuit
Noun
effort to secure or obtain.
raptor
Noun

bird of prey, or carnivorous bird.

rare earth element
Noun

one of 17 closely related metallic elements that occur together in nature and are difficult ot separate from each other.

rely
Verb

to depend on.

revolution
Noun

orbit, or a complete journey of an object around a more massive object.

river valley
Noun

depression in the earth caused by a river eroding the surrounding soil.

Roald Amundsen
Noun

(1872-1928) Norwegian explorer of the Arctic and Antarctic.

route
Noun

path or way.

Sami
Noun

people and culture native to northern Scandinavia.

Scandinavia
Noun

region and name for some countries in Northern Europe: Iceland, Norway, Sweden, Finland, and Denmark.

Noun

organism that eats dead or rotting biomass, such as animal flesh or plant material.

sea ice
Noun

frozen ocean water.

secondary consumer
Noun

organism that eats meat.

sedge
Noun

grass-like plant native to wetlands.

shipping channel
Noun

deep waterway where large boats regularly transport goods and people.

shipping route
Noun

path in a body of water used for trade.

Siberia
Noun

region of land stretching across Russia from the Ural Mountains to the Pacific Ocean.

solar radiation
Noun

light and heat from the sun.

Noun

astronomical event that occurs twice a year, when the sun appears directly overhead to observers at the Tropic of Cancer or the Tropic of Capricorn.

sophisticated
Adjective

knowledgeable or complex.

sovereignty
Noun

power or independence within a region.

Noun

native, geographic area in which an organism can be found. Range also refers to the geographic distribution of a particular species.

stilt
Noun
pole or post supporting a structure above the ground or water.
storehouse
Noun
building where supplies are kept.
structural engineering
Verb

study of the analysis and construction of structures, especially buildings.

Noun

evergreen forest in cool, northern latitudes. Also called boreal forest.

Noun

degree of hotness or coldness measured by a thermometer with a numerical scale.

temporary
Adjective

not lasting or permanent.

territory
Noun

land an animal, human, or government protects from intruders.

tertiary consumer
Noun

carnivore that mostly eats other carnivores.

textile
Noun

cloth or other woven fabric.

thaw
Verb

to melt, or turn from ice to liquid.

thermohaline circulation
Noun

ocean conveyor belt system in which water moves between the cold depths and warm surface in oceans throughout the world.

thrive
Verb

to develop and be successful.

tourism
Noun

the industry (including food, hotels, and entertainment) of traveling for pleasure.

trade
Noun

buying, selling, or exchanging of goods and services.

travel
Noun

movement from one place to another.

tundra
Noun

cold, treeless region in Arctic and Antarctic climates.

valuable
Adjective

worth a considerable amount of money or esteem.

vegetation
Noun

all the plant life of a specific place.

vermin
Noun
small animals that are destructive, annoying, and difficult to control.
vibrant
Adjective

lively.

Viking
Noun

seafaring people and culture native to Scandinavia between the 7th and 12th centuries.

voyage
Noun

long journey or trip.

Noun

state of the atmosphere, including temperature, atmospheric pressure, wind, humidity, precipitation, and cloudiness.

weatherization
Noun
practice of protecting a building and its interior from the effects of sunlight, precipitation, and wind.