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Northwest Passage - Map of Arctic Sea Ice

Global Warming is Opening Canada's Arctic

What Is the Northwest Passage?

The Northwest Passage is a sea route that connects the Atlantic and Pacific Oceans through the Canadian Arctic Archipelago. In the past the Northwest Passage has been virtually impassable because it is covered by thick, year-round sea ice. However, satellite and other monitoring confirm that the Arctic Ocean sea ice is declining in both thickness and extent.

The potential benefits of a clear Northwest Passage are significant. Ship routes from Europe to Japan, China and other eastern destinations would be 4000 kilometers (2500 miles) shorter. Alaskan oil could move quickly by ship to eastern North American and European markets. The vast mineral resources of the Canadian North will be much easier and economical to develop. This opportunity for expedient shipping between the Atlantic and Pacific is one of just a very small number of benefits that global warming might produce.

Arctic Sea Ice is Melting

There has been a progressive, year-by-year decline in the thickness and extent of Arctic sea ice. The images at right compare Arctic sea ice concentrations between 1979 and 2003. The top image shows the minimum sea ice concentration for 1979 and the bottom shows the minimum sea ice concentration for 2003. It is very clear in these images that the amount of Arctic sea ice was much lower in 2003. This decline continues.

NASA funded studies have shown that year-round, sea ice in the Arctic is declining at a rate of several percent per decade. As the ice cover is removed, solar radiation penetrates the water and warms it, instead of being reflected from the white ice.

Another factor that contributes to warming of the Arctic Oceans is the increase in discharge rates of rivers draining Eurasia. These fresh water rivers now receive increasing runoff from melting glaciers. This runoff is much warmer than the Arctic Ocean water. The net result is a slight warming of the Arctic Ocean waters and a dilution of salinity.

Northwest Passage Map

The map below shows possible routes through the Northwest Passage. Ships traveling west would enter the Passage through Baffin Bay, pass through the Canadian Arctic Archipelago by various routes, exit into the Beaufort Sea and then out into the Pacific Ocean through the Chukchi Sea and Bering Sea.

During the past few years satellite images taken near the end of the Arctic summer often show large portions of the Passage are relatively ice free. In September of 2006, satellite images showed that the Arctic Ocean was clear enough to sail directly to the North Pole from northern Europe. (Related: Arctic Ocean Features Map)

Early History of the Northwest Passage

The economic value of a short route connecting the Atlantic and Pacific Oceans was appreciated early. The Spanish referred to this route as the "Straight of Anián" and Francisco de Ulloa started searching the Baja California peninsula area for it in 1539. English explorers, including Martin Frobisher, John Davis and Henry Hudson searched for it from the Atlantic side in the late 1500's and early 1600's. These expeditions were unsuccessful.

Explorations continued through the 1600's and 1700's without success. Then in 1849 Robert McClure passed through the Bering Strait with the intent of sailing through to the Atlantic. His ship was trapped in the ice not far from making it to Viscount Melville Sound and probable passage to the Atlantic. Finally after spending three winters on the ice and dying of starvation, McClure and crew were rescued by a sledge party from one of Sir Edward Belcher's ships and transported by sledge to the Sound. McClure and his crew became the first to survive a trip through the Northwest Passage.

Norwegian explorer, Roald Amundsen and crew were the first to cross the Northeast Passage entirely by sea in 1906. Although the crossing was an important "first" it had little economic value because the journey took three years and used waters that were too shallow for commercial shipping. The first single season trip through the passage was by Henry Larsen and crew in 1944. Again the route taken was not deep enough for commercial shipping.

First Deep Draft & Commercial Vessel Crossing

In 1957, three United States Coast Guard Cutters, Storis, Bramble and SPAR became the first ships to cross the Northwest Passage along a deep draft route. They covered the 4,500 miles of semi-charted water in 64 days.

The first ship capable of carrying significant cargo to traverse the Passage was the SS Manhattan, a specially reinforced supertanker, in 1969. It was accompanied by the John A Macdonald, a Canadian icebreaker. This trip was taken to test the Northwest Passage as an alternative to building the Alaska Pipeline. At that time it was determined that the Northwest Passage was not economical and the Alaska Pipeline was built.

International Waters or Canadian Waters?

All routes through the Northwest Passage pass between the islands of the Canadian Arctic Archipelago. On that basis, Canada claims the route as "Canadian Internal Waters". However, the United States military has sent ships and submarines through the Passage without notification to Canada based upon the philosophy that the Passage is an International Water. This is one of many issues in the "who owns the Arctic Ocean?" question.

Future of the Northwest Passage

Commercial use of the Northwest Passage might be a very tiny benefit of global warming. Billions of dollars in transportation costs could be saved each year, in addition to time and energy resource use. Canada has the most to gain should the Northwest Passage become a viable shipping route. This will facilitate Canada's development of northern lands and provide an important economic and military possession if their claim to control is upheld.


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Northwest Passage satellite photo
Satellite image of the Northwest Passage and Canadian Arctic Archipelago acquired on September 3, 2009. Image credit NASA / Earth Observatory. Click to Enlarge Image

graph of arctic sea ice extent
Time series of the percent difference in ice extent in March (the month of ice extent maximum) and September (the month of ice extent minimum) relative to the mean values for the period 1979–2000. Based on a least squares linear regression for the period 1979-2009, the rate of decrease for the March and September ice extents is –2.5% and –8.9% per decade, respectively. NOAA Image.

Northwest Passage map
Red lines are possible routes for traversing the Northwest Passage. Click to Enlarge Image

deflected basement wall
U.S. Coast Guard Cutter Healy, the United States’ newest and most technologically advanced polar icebreaker. Credit: U.S. Coast Guard photo by Petty Officer Patrick Kelley

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