Sea ice

Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface (as does fresh water ice, which has an even lower density). Sea ice covers about 7% of the Earth's surface and about 12% of the world's oceans.^[1]^[2]^[3] Much of the world's sea ice is enclosed within the polar ice packs in the Earth's polar regions: the Arctic ice pack of the Arctic Ocean and the Antarctic ice pack of the Southern Ocean. Polar packs undergo a significant yearly cycling in surface extent, a natural process upon which depends the Arctic ecology, including the ocean's ecosystems. Due to the action of winds, currents and temperature fluctuations, sea ice is very dynamic, leading to a wide variety of ice types and features. Sea ice may be contrasted with icebergs, which are chunks of ice shelves or glaciers that calve into the ocean. Depending on location, sea ice expanses may also incorporate icebergs.

^ Wadhams, Peter (1 January 2003). "How Does Arctic Sea Ice Form and Decay?". Arctic theme page. NOAA. Archived from the original on 6 March 2005. Retrieved 25 April 2005.
^ Weeks, Willy F. (2010). On Sea Ice. University of Alaska Press. p. 2. ISBN 978-1-60223-101-6.
^ Shokr, Mohammed; Sinha, Nirmal (2015). Sea Ice – Physics and Remote Sensing. John Wiley & Sons, Inc. ISBN 978-1119027898.

[Wadhams-1] Wadhams, Peter (1 January 2003). "How Does Arctic Sea Ice Form and Decay?". Arctic theme page. NOAA. Archived from the original on 6 March 2005. Retrieved 25 April 2005.

[Weeks-2] Weeks, Willy F. (2010). On Sea Ice. University of Alaska Press. p. 2. ISBN 978-1-60223-101-6.

[Shokr&Sinha-3] Shokr, Mohammed; Sinha, Nirmal (2015). Sea Ice – Physics and Remote Sensing. John Wiley & Sons, Inc. ISBN 978-1119027898.

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