Polar Ice | Arctic in Context

This post is second in the three part Polar Ice series. The first part described the continent of Antarctica. This part describes the Arctic region at the north pole. Part three will describe the impacts that climate change seems to have on each region.

What region is defined as the Arctic? That depends on who you ask. As noted in this map, there are three generally accepted definitions. The most common definition from scientists is the region north of the Arctic Circle above 66.5˚ latitude. North of that latitude, the sun does not set on the summer solstice or rise on the winter solstice. A second common definition is the area where the average temperature for July is less than 10˚C or 50˚F. The third is the area north of the tree line. All three are indicated with arrows on the map.

Starting at the North Pole, follow the vertical line on the map toward the bottom. It is the 0˚ Prime Meridian and passes through Greenwich, England. Go to the left on 90˚W to pass through Canada, St. Louis, Central America, and the Galapagos Islands off the west coast of South America. The line toward the top of the map goes through the central  Pacific. Go to the right on 90˚E to pass through Russia, eastern India, and the Indian Ocean.

The north coast of Russia, islands to the north of Canada, northern Scandinavia, and Iceland are designated as an arctic maritime climate. They have very cold and stormy weather in the winter with snowfall totals from 60-120 cm (2-4 ft). Regions closer to the pole and the interior of Greenland have yearlong ice cover. Unlike the Antarctic which has most of its ice grounded on solid land, the Arctic has most of its ice floating on the sea. This map is a generalized view and does not represent any particular date of the year. Click to embiggen.

© Anthropolis Productions Limited 2002

© Anthropolis Productions Limited 2002 | Click to embiggen

The extent of sea ice in the Arctic as of December 17, 2014 is shown in the map below. Notice the map is rotated about 90˚ counterclockwise from the one above. The orange line is the median extent of ice for this date averaged from 1981-2010. Sea ice thickness in the 1980s was averaging about 2.3 meters (7.5 ft). It has decreased steadily since then to a current average value of about 1.5 meters (5 ft). More about the changes in the polar ice amounts in part three of this series.

National Snow and Ice Data Center | Boulder CO

National Snow and Ice Data Center | Boulder CO

The maximum area covered by the sea ice is in late winter. At the end of the summer months, the sea ice has melted to cover a much smaller area. This image shows the minimum extent this year in September 2014. Notice the median extent line for this date. Because of the extent of the sea ice, passage through from the Atlantic to the Pacific has been very difficult and treacherous, if not impossible. It was first navigated by Roald Amundsen in 1903–1906. Because of climate change, this Northwest Passage is becoming a greater reality.

National Snow and Ice Data Center | http://nsidc.org/

National Snow and Ice Data Center | http://nsidc.org/

The sea floor of the Arctic Ocean at its deepest is 5,502 meters (18,050 ft). The average depth is 987 meters (3,240 ft). A map of the floor shows the shallower continental shelf in light blue and the much deeper rugged regions in dark blue. The deep rift valley running horizontally and off the right edge of the image is the northernmost extent of the Mid-Atlantic Ridge. It is the result of the separation of tectonic plates.


Landsat | U.S. Geological Survey

Territorial claims in the Arctic are complicated. The Arctic includes land, territorial waters, and international waters. Land and territorial waters belong to five countries Russia, the United States, Canada, Norway, and Denmark. International law regulates these lands and waters. International water at the North Pole and surrounding it, is not owned by any country. The five countries have rights limited to an exclusive economic zone (EEZ) of 200 nautical miles (370 km) adjacent to their coasts. The sea floor beyond the exclusive economic zones are understood to be the “heritage of all mankind” and administered by the UN International Seabed Authority.

Certain parts of the Arctic sea region are in dispute for various reasons. All five countries regard parts of the Arctic seas as “national waters”, that is waters out to 12 nautical miles (22 km) from their coasts. These disputes affect what passages constitute “international seaways” and the future rights along them as in a future Northwest Passage.


Explore the Arctic Sea Ice News and Analysis web site for more information.

NOAA Arctic Theme Page


19 thoughts on “Polar Ice | Arctic in Context

  1. Interesting about the effect on the tectonic plates. I have another theory about changes in the tectonic plates…I think it has a lotto do with fracking and drilling for oil.

    • That is an interesting theory. My son is in Oklahoma with the Air Force. He regularly feels earthquakes due to fracking and drilling. Tectonic plates were on the move well before we humans started messing up this lovely planet.

      • Yes, i am aware of that but perhaps we are whacking the beehive so to speak with our man made activities.

  2. Well now I certainly have a better understanding of what makes up the arctic. Thanks for that! You’ve also made me think about those early polar explorers, such as Amundsen, and what courage and sacrifices these explorations required. Us human are a pretty damn determined lot, I don’t expect that will change. 🙂

  3. The economic implications of climate change are obviously huge in the Arctic region, both for drilling and for sailing the Northwest Passage. Territorial disputes over such things have been a prime cause of wars in history, of course, so it will be a major test of international civility in resolving the rules for this one. I used to wonder whether the U.N. was worth keeping, but if there was ever a need for such a forum, this one has to be near the top of the list. Excellent explanation, Jim.

    • I agree. People are and have always been inclined toward conflicting points of view and claims of ownership. We do need organizations to oversee our behavior and disputes.

      Thank for stopping by and your kind words today.

  4. Fascinating facts Jim. I simply had no idea when you said:
    “Unlike the Antarctic which has most of its ice grounded on solid land, the Arctic has most of its ice floating on the sea.”. And it makes sense that they would be more vulnerable to climate change. Thanks for the info. Fascinating post!

  5. I’ll add my usual etymological 2¢: the word Arctic comes from Greek arktos, meaning ‘bear,’ because the constellations of Ursa Major and Ursa Minor, the Great Bear and the Little Bear, are way up north in the celestial sphere.

  6. Hi Jim~sorry it has taken me so long to read this post. I’ve been helping my friend move to Florida. Don’t understand it myself, but there it is. I believe all of us has our home range built into our hearts, and for her it is Florida.
    I am shocked by how much thickness has been lost in the ice up there. The maps you show are very interesting. It will be interesting to see how all this shakes out, won’t it?

    • There is no time schedule for our posts. I’m glad you are able to be persistent. So far, the trends are not looking favorable. The Arctic changes are going to impact our midwest and northeast weather patterns in the future.

      Did you get to Florida with your friend, or just help pack? I can see visiting FL in cold weather as an escape. But I don’t choose it for daily life. I like the 4 seasons of the heartland. Change is a good thing.

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