March 8, 2015

Changing winds herald climate risks for Arctic airports

By IVAN SEMENIUK

Study suggests gradual shifts in average wind speed and direction due to climate change make some airstrips less safe

Even as a boy, Andrew Leung was enamoured with flight and loved to go with his father to watch the planes flying in and out of Hong Kong's Kai Tak airport. Sandwiched between the harbour and a wall of skyscrapers, the now-defunct airport was a notoriously challenging place to land a commercial airliner.

"I was very young at that time and couldn't comprehend the difficulty for the pilots," Mr. Leung said.

Now a PhD candidate at the University of Toronto, Mr. Leung's love of aviation has led him to investigate a different kind of challenge for pilots in the Canadian Arctic and the communities that depend on them – climate change.

As part of a continuing study, Mr. Leung has been gathering meteorological data from small airstrips around Hudson Bay and the Eastern Arctic. The results, which have yet to be published, suggest that gradual shifts in average wind speed and direction due to climate change will render at least some of those airstrips less safe in the future unless costly upgrades are put in place to help mitigate the increased risk.

"Historically, some of these airstrips have been designed so that when you're landing and taking off you're not fighting the wind," said William Gough, a climatologist who is supervising the research. "So if [wind] direction changes or magnitude changes, then it's a big concern."

A potential reduction in airport viability is a problem for any community that depends on year-round air transportation for food, supplies and medical services, said Stephen Nourse, executive director of the Northern Air Transport Association, an industry association.

"An aircraft coming in up there is more like the local bus, delivery truck and ambulance," all rolled into one, he said.

Climate change is an issue of growing relevance for airport operators in the Arctic for a number of reasons, including the threat to runway stability posed by the disappearance of permafrost and more days of "shoulder season" weather in the spring and fall when temperatures are near the freezing point and there is a greater change of ice buildup on runways and aircraft.

Some locations are already bearing the brunt of increased costs due to changing climatic conditions. At Iqaluit Airport, the busiest in the Eastern Arctic, reduced sea ice and shorter winters mean more days when the airport is socked in with fog, which can also coat the runway with ice and require chemical de-icing. The difference between a good year and a bad year in chemical supplies alone can amount to $400,000 said the airport's director, John Hawkins.

Mr. Leung's research on wind adds a new wrinkle. Ideally, pilots prefer to land in a direction that minimizes dangerous crosswinds. Depending on a runway's alignment, either an increase in average wind speed or a shift in prevailing wind direction – or a combination of two – can serve to increase crosswinds. Even a modest increase could push runway conditions over a threshold that makes it riskier to attempt a landing, he said.

So far, he has delved into to several decades worth of Environment Canada data gathered at six airports in the eastern Arctic and Subarctic. Two out of the six show a significant change in wind direction, including the airport at Baker Lake and an abandoned runway in central Quebec, while most of the others show a trend toward increasing wind speed.

While the changes are not linked to any particular mishaps, Mr. Leung noted that the rate of weather-related aviation accidents in the North is 25 times higher than in the rest of Canada.

The findings are in rough agreement with what climate models suggest will be in store for the Arctic as the planet warms.

"Patterns of wind direction appear to be changing," said Adam Fenech, who works with computer models of future climate at the University of Prince Edward Island. Over the previous 30 years, prevailing winds have typically flowed west-to-east across the Arctic, he added, but more recently are they are blowing more from the south during the summer months.

Such changes are coming to light even as Transport Canada is in the midst of commissioning an assessment of vulnerabilities due to climate change at three key northern airports, including Churchill, Manitoba; Inuvik in the Northwest Territories and Cambridge Bay, Nunavut.

The first two locations are busy aviation hubs in the North, while Cambridge Bay is expected to see increased air traffic due to the Canadian High Arctic Research Station, which is scheduled to open there in 2017.

The federal assessment "is intended to identify airport infrastructure that could be at risk of failure, damage, loss or service and/or deterioration from extreme climatic events or significant changes to the climate," said Transport Canada spokesman Ben Stanford. Until the results of the assessment are available, he added, "no specific action is planned."

Prof. Gough said is was too early to know where wind might rank in the list of reasons why climate change is a problem for dozens of smaller airfields in the North. But with the cost of relocating a runway or outfitting it with sophisticated systems for guiding aircraft easily running into the tens of millions of dollars, the potential impact on northern communities is enormous.

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