Arctic Ocean

The Arctic Ocean is the smallest and shallowest of the world's five oceanic divisions. It covers about 14,060,000 km² and is the coldest ocean on Earth. Even though the International Hydrographic Organization calls it an ocean, some oceanographers refer to it as the Arctic Mediterranean Sea or North Polar Sea. It is sometimes described as an estuary of the Atlantic Ocean and is the northernmost part of the entire world ocean.

The Arctic Ocean surrounds the North Pole and reaches down to around 60°N. It is bordered by Eurasia and North America, with its edges defined by natural features like the Bering Strait on the Pacific side and the Greenland Scotland Ridge on the Atlantic side. Most of the time, it is covered by thick sea ice, especially in winter.

The Arctic Ocean's surface temperature and salinity change with the seasons as the ice cover melts and freezes. It has the lowest average salinity of all the major oceans because of low evaporation, lots of fresh water from rivers, and limited water exchange with saltier oceans. In recent years, the summer ice has been shrinking. According to the US National Snow and Ice Data Center, the amount of sea ice has been steadily decline in sea ice over time.

History

People have lived in the North American polar region for thousands of years. During that time, sea levels were lower. People crossed a land bridge from Siberia to North America, which helped people settle in the Americas.

Early groups in the Arctic included the Pre-Dorset, Saqqaq culture, and Dorset culture. The Thule people, ancestors of today’s Inuit, later spread across the Arctic region of North America.

For much of European history, the Arctic was unknown to many. Early explorers and mapmakers were unsure about the areas around the North Pole. Over time, more expeditions explored the Arctic, which helped people learn more about the place.

In the 1800s, many people believed there was an Open Polar Sea. Explorers looked for this large area of water, but instead they found thick ice that stayed all year.

In the 1900s, important events happened, such as the first time a ship went across the Arctic Ocean, led by Fridtjof Nansen. Later, Wally Herbert made the first crossing on the surface. Submarines and special ice-breaking ships also went through the North Pole.

During World War II, the Arctic Ocean was an important area. Allied forces used it to send supplies to the Soviet Union through its northern ports. In 1954, Scandinavian Airlines began the first regular flights over the Arctic Ocean.

Geography

The Arctic Ocean is the smallest and shallowest of the world's oceans. It covers an area of about 14,056,000 km² (5,427,000 sq mi), almost the size of Antarctica. It is the only ocean smaller than Russia.

The Arctic Ocean is surrounded by the land masses of Eurasia (Russia and Norway), North America (Canada and the U.S. state of Alaska), Greenland, and Iceland. It connects to the Pacific Ocean through the Bering Strait and to the Atlantic Ocean through the Greenland Sea and Labrador Sea. Some of the largest seas in the Arctic Ocean include the Barents Sea, Hudson Bay, and Greenland Sea.

Main article: Borders of the oceans § Arctic Ocean Main article: List of islands in the Arctic Ocean

Geology

The rocks around the Arctic Ocean were formed long ago. Later, during the Jurassic and Triassic periods, sediment settled, creating places where oil and gas can be found today. As continents moved, the Arctic Ocean opened up.

The Arctic Ocean formed when the supercontinent Pangea split apart. The seafloor spread from ridges like the Gakkel Ridge, moving the Lomonosov Ridge away from land. Because of ice and harsh conditions, scientists still don’t know everything about the Arctic Ocean’s geology. Some areas might hold oil.

Oceanography

The Arctic Ocean has a special way of moving water. Near the top, there is colder water from big rivers like the Ob, Yenisei, Lena, and Mackenzie. This water stays on top because it is lighter than the saltier water below. Between these layers is something called a halocline, where the water gets saltier and warmer as you go deeper.

The Arctic Ocean moves water in a way that is similar to the Mediterranean Sea. It holds about 18.07 × 10⁶ km³ of water, which is a small part of all the world's oceans. Water flows in from the Pacific and Atlantic Oceans and makes three different kinds of water masses. The deepest water, called Arctic Bottom Water, starts around 900 meters deep. It helps form water in the Atlantic and affects Earth's climate.

The Arctic Ocean is mostly covered by sea ice, which changes a lot during the year. The amount of ice has been getting smaller over the past few decades. This ice can move around because of wind and ocean currents. Sometimes big pieces of ice, called icebergs, break off from islands and glaciers. They can be tricky for ships.

Climate

The Arctic Ocean has a polar climate, so it is very cold most of the time. Winters are long and dark, and summers are short. During summer, the sun never sets, called the midnight sun. Temperatures can sometimes get above freezing, and storms can bring rain or snow.

The surface water of the Arctic Ocean stays around −1.8 °C (28.8 °F), close to the freezing point of seawater. This cold water sinks and helps form sea ice. The amount of ice changes with the seasons, and snow often covers the ice for much of the year.

The Arctic is warming up faster than other parts of the world.

See also: Climate change in the Arctic

Biology

The Arctic Ocean has special plants and animals that can live in its cold waters. In the spring and summer, tiny plants called phytoplankton and algae under the ice grow fast. These plants are eaten by small animals like copepods and euphausiids. Bigger animals like herring, polar cod, seals, whales, and polar bears eat these smaller animals.

The Arctic Ocean is home to some animals in danger, like walruses and some kinds of whales. This area changes with temperature more quickly than other places. Interesting sea creatures here include the Lion's mane jellyfish and the banded gunnel, the only gunnel that lives in this ocean.

Natural resources

See also: Natural resources of the Arctic, Territorial claims in the Arctic, and Marine mammal

The Arctic Ocean has many important resources. These include petroleum, natural gas, placer deposits, polymetallic nodules, sand, gravel, fish, seals, and whales. Many countries value these resources.

Some countries, like the United States, Russia, Canada, Norway, and Denmark, disagree about who owns the resources in a special area in the middle of the Arctic Ocean. This area may have a lot of oil and gas, which could help meet the world's energy needs.

Environmental concerns

Main articles: Climate change in the Arctic, Ozone depletion, and Pollution in the Arctic Ocean

The Arctic ice is getting thinner. This change can affect the Earth's climate. Scientists think the Arctic might have no ice in the summer by the year 2040. This can change ocean currents and weather around the world.

Melting ice can also let out methane, a strong greenhouse gas, into the atmosphere. There are also worries about radioactive contamination from old activities like nuclear tests. In 2015, several countries agreed to protect part of the central Arctic Ocean from fishing until more is learned about its marine life.