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
There are two oceans in Earth's polar regions.
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.
Last modified June 18, 2007 by Lisa Gardiner.
Shop Windows to the Universe Science Store!
The Summer 2010 issue of The Earth Scientist
, available in our online store
, includes articles on rivers and snow, classroom planetariums, satellites and oceanography, hands-on astronomy, and global warming.
You might also be interested in:
North of the Arctic Circle (at 66.5°N latitude) you will find the Arctic Ocean surrounded by the continents of Europe, Asia, and North America. You will find the geographic North Pole and the magnetic...more
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
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
About 70% of the Earth is covered with water. Over 97% of that water is found in the oceans. Everyone who has taken in a mouthful of ocean water while swimming knows that the ocean is really salty! Dissolved...more
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
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
“Polar bears are one of nature’s ultimate survivors, able to live and thrive in one of the world’s harshest environments, but we are concerned the polar bears’ habitat may literally be melting” said US...more