Lands and Environment

Thick ice still encumbering Northwest Passage

The following is the first in a two-part series by scientific contributor Olivia Mussells on marine transportation and port infrastructure in the Canadian Arctic.

Despite the ongoing speculation, it seems unlikely that the Northwest Passage, the legendary path for ships winding through the islands of the Canadian Arctic Archipelago, will become safe for frequent cargo shipping in the near future.

A recent study has found the ongoing presence of thick and hazardous ice conditions in the passage persists, despite the warming temperatures that have been observed in the Arctic.

The study, published in Geophysical Research Letters in September 2015, reveals the results of two years of ice thickness measurements observed in the passage. Overall, mean ice thickness was found to be between two to three metres, depending on the region. The researchers also identified numerous features where the ice was more than four metres thick and longer than 100 metres—about as long as a vessel that might typically travel in the region. Undoubtedly, these large ice features would present a threat for a ship and are most likely to survive the summer melt season due to their size and thickness.

The researchers, Christian Haas and Stephen Howell, performed the study using a helicopter and airplane to carry out airborne electromagnetic (AEM) soundings in May 2011 and April 2015. In total, 1,678 kilometres were surveyed. AEM works by sending an electromagnetic pulse that penetrates the ice to the point where the ice meets the sea. The rebound signal is used to measure the distance between the plane and that interface. At the same time, a laser altimeter is used to scan the surface of the ice, measuring the distance between it and the aircraft. The resulting difference between these two values gives the thickness of the ice.

What is interesting about this research is the identification of multi-year ice in the passage. Sea ice is usually divided into two categories: first-year ice and multi-year ice. Multi-year ice is defined as any ice that has survived at least one summer melt period. This ice is stronger than first-year ice and usually thicker, as well. This ice is much more dangerous for ships and can do real damage to a ship’s hull.

Despite warming temperatures in the Arctic, multi-year ice still frequently forms within the Northwest Passage, and that very thick, hazardous ice from the Arctic Ocean can survive the journey south into the passage. Both become an obstacle to ships transiting the Canadian Arctic.

In the Western Canadian Arctic, there are two sources of multi-year ice: first-year ice that forms around the Canadian Arctic Archipelago and then survives the summertime, and multi-year ice that has drifted south from the Arctic Ocean. The multi-year ice from the Arctic Ocean that gets pushed up along the western edge of the Canadian Arctic is some of the thickest sea ice in the world.

The researchers used ice charts published by the Canadian Ice Service in order to track where the multi-year ice found in the Northwest Passage had come from. Some of it had formed within the passage, while the rest had been carried from the Arctic Ocean. This shows that, despite warming temperatures in the Arctic, multi-year ice still frequently forms within the Northwest Passage, and that very thick, hazardous ice from the Arctic Ocean can survive the journey south into the passage. Both become an obstacle to ships transiting the Canadian Arctic.

The results of this research are important for a number of reasons. To begin with, sea ice thickness measurements are difficult to acquire and usually require visiting the Arctic—a difficult and expensive prospect. This is the first study of its kind over the passage. The last systematic collection of sea ice thicknesses in the Canadian Arctic was carried out in the 1970s by Humphrey Melling.

It must be acknowledged that these values were collected during what are considered late winter conditions, when the ice is still at its peak thickness and extent, and most, if not all, shipping in the Canadian Arctic happens during the summer. However, as Haas pointed out in an interview: “it does matter how thick the ice was in April at the end of the season.” The spring ice thickness can be used to predict the ice conditions in September when the ice is at its minimum. There has already been some work to create models to forecast ice melt and weather throughout the summer, but these need initial ice thicknesses to be well calibrated.

“We need better predictions for weather in the summer, of where and when the ice will melt,” said Haas, who has another trip to the Northwest Passage planned for the spring of 2016. The repetition of measurements will be necessary to build a strong database of baseline information and account for the variability that is seen from year to year.

This study adds to the growing consensus that the Northwest Passage might not be economically viable for cargo shipping in the near future. These observations also support the conclusions of a study by Laurence C. Smith and Scott R. Stephenson carried out in 2013, based on several climate models, which estimate it could be another 40 years before the Northwest Passage is a safe and popular route.

So far there have been two transits of cargo through the passage: the first by the Danish-owned MS Nordic Orion, which was accompanied by a Canadian icebreaker, and the second by MV Nunavik, an ice strengthened vessel owned by the Canadian shipping company Fednav, which made the voyage unescorted.

Still, ongoing intrusions of multi-year ice and the presence of thick ice that can survive well into the summer season continue to threaten any ships coming through the passage. Given these hazards and the difficulty of insuring a ship travelling through the passage, it is unlikely that such a transport route will become economically viable any time soon, especially when the opening of the passage and melting of the ice are so unpredictable. Ongoing research is needed to provide baseline for monitoring sea ice thickness in order to improve ice forecasts in the area.◉

Photo credit: istockphoto/Dalriada50

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