Sunset over sea ice off the coast of Antarctica captured from the Nathaniel B. Palmer, an NSF research icebreaker ship, during an Antarctic oceanography research cruise. Click on image for full size (55 Kb) NOAA Corp Collection, Photographer Michael Van Woert

There are two oceans in Earth’s polar regions: the Arctic Ocean, which occupies most of the north polar region, and the Southern Ocean, which surrounds the continent of Antarctica in the south polar region.

Oceans in the polar regions are a bit different from the other oceans on Earth (the Atlantic, Pacific, and Indian Ocean). There is often sea ice at the surface of polar oceans, especially during the winter months. Both the Arctic Ocean and the Southern Ocean are homes to unique marine ecosystems that thrive in the cold conditions.

Seawater from polar regions can be denser than seawater from other regions. This is because seawater in the polar oceans is often colder than other seawater. It can also become more saline than normal in the winter when sea ice freezes at the ocean surface. The salty part of the water does not freeze, making the remaining seawater saltier. Because it is denser, this seawater sinks to the bottom of the ocean. It travels in slow currents around the bottom of the world’s oceans as an essential part of the pattern of global ocean circulation called thermohaline circulation.

The polar oceans are affected greatly by global warming. Scientists are actively studying how the polar oceans, the sea ice at their surface, and the marine life within them, are changing in response to recent climate change. They have found that sea ice in the Arctic Ocean is melting more rapidly than previously thought, so quickly in fact that by the year 2040 there may not be any sea ice in the Arctic during summer months. Because sea ice reflects a large amount of incoming solar energy, less sea ice means that less solar radiation is reflected back out to space and more of it is absorbed, increasing the rate of warming. The melting sea ice threatens Arctic Ocean species such as polar bears. Scientists are currently studying the effect of less sea ice on polar bears. In the Antarctic, scientists are studying the effect of less sea ice on the penguin breeding season.

Eventually, global warming could also disrupt global ocean circulation. If it gets warm enough that sea ice no longer forms in the polar regions, the seawater would not be extra salty and thus would not be as dense. If the water were warmer it may not be as dense either. This could prevent the formation of deep water, potentially slowing or even stopping global ocean circulation. A shutdown of this circulation could have large consequences for many different aspects of our planet including consequences for regional climates, the severity of weather events, and marine ecosystems.

Sunset over sea ice off the coast of Antarctica captured from the Nathaniel B. Palmer, an NSF research icebreaker ship, during an Antarctic oceanography research cruise. Click on image for full size (55 Kb) NOAA Corp Collection, Photographer Michael Van Woert

There are two oceans in Earth's polar regions.

• The Arctic Ocean is in the north polar region.
• The Southern Ocean is in the south polar region.

The oceans that are in the polar regions are a bit different from other oceans on Earth. There is often sea ice at their surface, especially during the winter months. And those chilly waters are home to some unique marine life.

Seawater from polar regions can be denser than seawater from other places. This is because seawater in the polar oceans is cold, and this makes it denser. It can also become saltier than other seawater during the winter when sea ice freezes at the ocean surface removing some of the freshwater to make the ice, which concentrates the salts. The denser seawater sinks to the bottom of the ocean. It travels out of the polar regions in slow currents that travel around the bottom of the world’s oceans as part of the pattern of global ocean circulation called thermohaline circulation.

The polar oceans are warming up as Earth’s climate changes. Scientists are studying how the polar oceans, the sea ice at their surface, and the marine life within them, are changing in response to recent climate change. They have found that sea ice in the Arctic Ocean is melting so quickly that by the year 2040 there may not be any sea ice in the Arctic during summer months. The melting sea ice threatens Arctic Ocean species such as polar bears. In the Antarctic, scientists are studying the effect of less sea ice on the penguin breeding season.

If it gets warm enough that polar oceans are warmer and sea ice no longer forms, the seawater would not be as dense and would not flow down to the ocean bottom, potentially slowing or stopping global ocean circulation. If the oceans stopped their pattern of global circulation, many aspects of our planet would change including regional climates, the severity of weather events, and marine ecosystems.

Sunset over sea ice off the coast of Antarctica captured from the Nathaniel B. Palmer, an NSF research icebreaker ship, during an Antarctic oceanography research cruise. Click on image for full size (55 Kb) NOAA Corp Collection, Photographer Michael Van Woert

The oceans that are in the polar regions are a bit different from other oceans on Earth. There is often sea ice at the surface, especially during the winter months. And those chilly waters are home to some unique marine life.

There are two oceans in Earth's polar regions.

• The Arctic Ocean is in the north polar region.
• The Southern Ocean is in the south polar region.

Seawater from polar regions can be denser than seawater from other places. It is denser because it is cold. It can also become saltier than other seawater and that makes it denser too. The denser seawater sinks to the bottom of the ocean. It travels out of the polar regions in slow currents that travel around the bottom of the world’s oceans.

The polar oceans are warming up as Earth’s climate changes. Scientists are studying how the polar oceans, the sea ice at their surface, and the marine life within them, are changing because the Earth is getting warmer. They have found that sea ice in the Arctic Ocean is melting. Polar bears and other species rely on the sea ice, so they might be in trouble as sea ice melts. In the Antarctic, scientists are trying to figure out if penguins will be affected as sea ice melts there.