Shop Windows to the Universe

Science, Evolution, and Creationism, by the National Academies, focuses on teaching evolution in today's classrooms. Check out the other publications in our online store.
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
NOAA Corp Collection, Photographer Michael Van Woert

Polar Oceans

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.

Last modified June 18, 2007 by Lisa Gardiner.

Shop Windows to the Universe Science Store!

The Fall 2009 issue of The Earth Scientist, which includes articles on student research into building design for earthquakes and a classroom lab on the composition of the Earth’s ancient atmosphere, is available in our online store.

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

The Arctic: Earth's North Polar Region

North of the Arctic Circle (at 66.5°N latitude) you will find the Arctic Ocean surrounded by the northernmost parts of the continents of Europe, Asia, and North America. You will find the geographic North...more

The Southern Ocean

The Southern Ocean is a bit different. Many mapmakers do not even recognize it as an ocean. The Southern Ocean (sometimes known as the Antarctic Ocean or South Polar Ocean) surrounds Antarctica in the...more

Antarctica

Antarctica is unique. It is the coldest, windiest, and driest continent on Earth. The land is barren and mostly covered with a thick sheet of ice. Antarctica is almost entirely south of the Antarctic Circle...more

The Antarctic Region

What Will You Find There? South of the Antarctic Circle (at 66.5°S latitude) you will find the continent of Antarctica surrounded by the Southern Ocean, the geographic South Pole and the magnetic South...more

Sea Ice in the Arctic and Antarctic

Sea ice is frozen seawater. It can be several meters thick and it moves over time. Although the salts in the seawater do not freeze, pockets of concentrated salty water become trapped in the sea ice when...more

Salinity

About 70% of the Earth is covered with water, and we find 97% of that water in the oceans. Everyone who has taken in a mouthful of ocean water while swimming knows that the ocean is really salty. All water...more

Thermohaline Circulation: The Global Ocean Conveyor

The world has several oceans, the Pacific, the Atlantic, the Indian, the Arctic, and the Southern Ocean. While we have different names for them, they are not really separate. There are not walls between...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF