1999 Arctic storm sign of things to come: experts

MARGARET MUNRO
Postmedia News

There was never any question the Arctic storm was brutal, whipping up the Beaufort Sea with 70 kilometre per hour winds and sending sea water surging onto the low-lying river delta.

But scientists reported Monday the impact of the 1999 storm on the Mackenzie Delta, in the northwest Arctic, was unmatched in 1,000 years. The sea water swept up to 30 kilometres inland inundating lakes and killing shrubs and vegetation creating a “dead zone” than has yet to recover, they say.

“It’s unprecedented over the last millennium,” says John Smol of Queen’s University in Kingston, Ont., who warns the storm is an “ominous” sign of things to come as the climate changes.

Rising sea levels are expected to flood low-lying regions across the world by the end of the century, but the threat is especially acute in polar regions, where shrinking sea ice increases the risk of storm surges, says Smol and a team academic and federal scientists from across Canada. They reported the findings Monday in the Proceedings of the National Academy of Sciences.

They say Arctic communities “need to be prepared” for the changing intensity of marine storm surges.

In late September 1999, fierce winds blew in from the northwest hammering the Mackenzie delta for two days, creating a surge two to two-and-half metres high that sent sea water 25 to 30 kilometres inland from the coast, says co-author Joshua Thienpont, also of Queen’s.

Because the delta is so remote and records only go back a few decades, the researchers used vegetation and lake sediments to gauge the storm’s impact.

Dead alder bushes are one of the obvious indications of the “dead zone” that covers “hundreds of square kilometres,” says Thienpont.

More than half of the shrubs sampled were dead within a year of the 1999 surge, while another 37 per cent died within five years. A decade after the flood, the soil still has high concentrations of salt.

Sediments from the bottom of one of hundreds of small lakes dotting the Mackenzie Delta provided the historical significance. The sediments, which go back more than 1,000 years, showed a “striking shift” from freshwater to saltwater algae species that has never occurred before.

“Our data suggest that saltwater inundations of this magnitude, and the associated ecological impacts, have not occurred in at least the last millennium,” the team reports.

There is no sign of biological recovery in the lake, the scientists say, and “large areas of terrestrial vegetation remain dramatically altered over a decade later, suggesting that these systems may be on a new ecological trajectory.”

Smol said in an interview Monday that the Arctic is being hit by “a triple whammy” — rising global sea level, more extreme and episodic weather, and retreating sea ice that leave low-lying parts of the north more vulnerable to storm surges.

“This is not part of some normal cycle,” says Smol, adding that “something has gone past the regular bounds of variability when you see data like this.”

The study adds to the “enormous volume of literature out there that we are entering into times that are not on our radar screen,” he says. “And we better get ready to adapt.”

There are ambitious plans to tap into the huge stores of fossil fuels under the Mackenzie Delta, and the changing climate poses challenges for drilling, shipping and pipeline operations, says Thienpont, who has just returned form the delta where he continues to assess the changes underway.

“It is absolutely essential that we understand what is going on,” Thienpont said.