Melting Makes Northwest Passage Passable
October 29, 2007 By: Mary Jo WagnerScientists and researchers are in agreement: the Arctic's waters will be virtually ice-free in the future. However, a new SAR (synthetic aperture radar) mosaic of the Arctic showing an ice-free Northwest Passage — a sea lane that could provide a "shortcut" from Europe to Asia through the Canadian Arctic — is causing some scientists to change their predictions dramatically.
Based on climate models, experts have issued predictions ranging from 2020 to 2070 for when the Arctic's sea ice will completely melt in the summertime. The Envisat ASAR (advanced synthetic aperture radar) mosaic produced by the Danish National Space Center (DSNC), however, is pushing that forecast forward by as much as 15 years.
"The ice cap is at an extreme low," said DNSC's Leif Toudal Pedersen in a media statement. "In one year, the ice cover dropped by one million square kilometers to now extend to about three million square kilometers. That's about 45 percent less than the average from 1997-2000 — a reduction in size equal to Western Europe.
"Over the last ten years the ice cover has shrunk by about 100,000 square kilometers per year on average, so a drop of one million square kilometers in just one year is extreme," he added. "The strong reduction in one year certainly raises flags that the summer ice may disappear much sooner than expected. We urgently need to understand better the processes involved."
Though Arctic ice naturally advances each winter and retreats each summer, scientists say they have never seen such an accelerated rate of loss in the 30 years since satellites began collecting data over the region. And never have they seen a fully navigable Northwest Passage — typically, the sea route remains impassable even in the summer, when multi-year pack ice is reduced. Climate models have projected that the passage would eventually open as global warming continued to melt the Arctic ice, but no one predicted that it would happen so soon.
"We have 50 years of data on the Arctic and in all that history, we have never seen anything like what we see today," said Pedersen. "The results of this study show that it may only take 15-20 years before the polar sea ice will melt entirely in the summer."
The SAR mosaic also reveals that the Northeast Passage, a similar sea route that meanders along Siberia's coast, is nearly clear of ice.
 Created from nearly 200 Envisat scenes, this Arctic mosaic reveals that the most direct route of the Northwest Passage (the orange line) across northern Canada is fully navigable. The blue line traces the Northeast Passage along the Siberian coast, which is only partially obstructed by ice. |
Mosaic Messages
In early September 2007, DNSC acquired nearly 200 Envisat ASAR scenes from the European Space Agency (ESA) to create the Arctic mosaic, which the organization released to the world on September 14. ESA provided the free imagery to DNSC as part of its contribution to the International Polar Year (IPY), an intensive scientific research program focusing on the Arctic and the Antarctic.
Launched in March 2007, this IPY aims to pick up where the last IPY left off nearly 50 years ago. It involves scientists in more than 60 countries conducting 48 diverse projects. Participants seek to improve our knowledge about the physical, biological, environmental, and social processes in the two polar regions, and to provide the foundation to better predict future developments. The last IPY was held in 1957-1958.
Dramatic as the mosaic is, it is just one of a long line of SAR "pictures" indicative of global warming. In 2005, Envisat ASAR imagery revealed the Arctic's perennial ice cap had shrunk by 280,000 square miles — an area the size of Turkey. In August 2006, RADARSAT-1 alerted the Canadian Ice Service to the collapse of the Ayles ice shelf off Ellesmere Island — a 66-kilometer chunk of ice that broke off in less than one hour. And almost one year to the day of DNSC's mosaic, scientists at ESA's Oceans/Ice Unit produced an Envisat ASAR mosaic that showed a massive crack the size of the British Isles had opened in the Arctic's perennial sea ice pack north of Svalbard, extending from the Russian Arctic to the North Pole.
At the time, Mark Drinkwater, the head of the ESA unit, said, "This situation is unlike anything observed in previous record low ice seasons. It is highly imaginable that a ship could have passed from Spitzbergen through what is normally pack ice to reach the North Pole without difficulty."
He went on to say, "If this anomaly trend continues, the Northern Sea Route between Europe and Asia will be open over longer intervals of time, and it is conceivable [that] we might see attempts at sailing around the world directly across the summer Arctic Ocean within the next 10 to 20 years."
It's a prediction that is being echoed today, with the clear picture of a fully navigable Northwest Passage. Though there is considerable doubt that commercial shipping through the region will be a reality anytime soon — the passage is seasonal and unpredictable, and there are very few ports — the prospect of a 2,480-mile shortcut from Europe to Asia is an enticing possibility, especially when compared with the current routes through the Panama Canal.
The potential increase in accessible waterways is also opening up more heated geopolitical debate among Canada, Russia, the European Union, and the United States over which country can rightfully lay claim to the waters. Though SAR imagery cannot resolve the international competition for control, it can and is providing a clear picture of the Arctic's environmental fate — which may be realized sooner rather than later.
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