The Arctic Ocean
is too warm to freeze solid
Q: Why doesn't the Arctic Ocean freeze into a solid block of ice? -Liz
A: The water's too warm below the ice cap. Sea ice-present in the Arctic all year long-floats on top and
insulates the warmer water below like an 8-foot thick white blanket.
[NOAA] Spring stream flowing on the ice, Alaska North Slope
Moreover, deeper water is saltier and therefore must drop to a lower temperature to freeze. Salt crystals
interfere with the formation of ice crystals. This means that salty water must be colder than fresh water
before it can freeze-as low as 28 degrees Fahrenheit (-1.8 degrees Celsius).
The key to the answer, however, is ocean circulation. That's how warm water gets into the Arctic Basin.
The warm Gulf Stream sweeps northward along the eastern US coastline and splits: part into the Arctic
Ocean and part out toward northern Europe. This warm water enters the Arctic Basin with a temperature
of about 34 to 37 degrees F and gradually cools as it spreads westward. By the time it reaches the
Beaufort Sea (a distance of about 1,200 miles or 2,000 kilometers, A in figure), it is a chilly 33 degrees F--
but still well above the freezing point of saline water.
[theodora.com] Gulf Stream enters the Arctic Ocean
"If the Arctic Basin were isolated by surrounding continents [with no incoming warm water], it probably
would freeze down to ocean bottom," says Bart Geerts, atmospheric sciences professor at the University
It doesn't, though, because warmer Atlantic waters everywhere underlie Arctic surface water.
(Answered May 31, 2002)
Ask Jack, USATODAY.com: polar climates
U of Wyoming: The Arctic Ocean and sea ice
theodora.com: Maps courtesy of www.theodora.com/maps . Used with permission.