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Melting Arctic ice cap top Canadian weather story of 2007: Environment Canada

Canadian Press: Alan Black - December 27, 2007

TORONTO - A chunk of ice the size of Ontario melted away in Canada's attic this year and that stunning development in the high Arctic was selected as Environment Canada's top weather story of 2007.

On Sept. 12, scientists were stunned by satellite images revealing that Arctic sea ice had shrunk to about four million square kilometres - a 23 per cent reduction from the previous record of 5.3 million square kilometres in 2005.

"You can imagine the kind of emotion and shock when climatologists and scientists examined the ice imagery ... and they could see the ice absolutely disappearing before their eyes," said senior climatologist David Phillips.

"This huge chunk of ice the size of Ontario vanished within one year."

The threat of a devastating flood in British Columbia was second on the list, followed by pre-winter storms across Canada, a hot and sticky summer on the Prairies, a dry summer in southern Ontario and the effects of Hurricane Noel in eastern Canada.

The list, made public Thursday, was rounded out by falling water levels in the Great Lakes, the late start to winter, record Prairie storms and Canada's first F5 tornado.

One of the most remarkable effects of the melting ice cap was the opening of the fabled Northwest Passage, which was nearly ice-free and navigable for about five weeks in late summer.

Of its 2,300 kilometre length, there was only about 20 kilometres of ice instead of the usual 400.

The unprecedented shrinkage of Arctic sea ice is due to several factors, said Phillips.

"There were very favourable winds that kind of kicked the ice out into the Atlantic. You had a lot of sunshine this year in the Arctic, which helped to decay the ice cap, and a pattern of persistent warm temperatures."

What remains to be seen is how the dramatic transformation of the Arctic surface from a highly reflective white snow or ice to dark heat-absorbing sea water will affect planetary climate.

"When you go from a surface that reflects 90 per cent of the radiation that comes in to a surface that absorbs 95 per cent of the sun's rays ... I think it has incredible implications for all people," warned Phillips.

"What those implications are, I just don't think we quite nearly know yet."

In early spring, experts began bracing for the worst flooding in B.C.'s history when the mountain snowpack built up at a record rate and posed a major threat to people living along swollen water courses, especially in north-coastal B.C. and in the south along the Fraser River.

Instead of the snowpack ripening and lessening in April as usual, more snow was piled on and once May arrived, a perfect recipe for disaster was in place.

By June however, rivers had peaked or were falling and the Fraser Valley avoided catastrophe when cooler temperatures returned and a soppy storm diverted away at the last moment.

Had the flooding materialized, said Phillips, "It would have been a $6 billion hit."

Pre-winter storms across the country took third place on the top-10 list.

"When Dec. 1 rolled around, we had huge dumps of snow in Victoria-Vancouver," said Phillips.

There was brutal cold on the Prairies, heavy snow in southern Ontario, southern Quebec and even more misery in Atlantic Canada.

"Power outages in Prince Edward Island and along the Avalon Peninsula of Newfoundland were some of the worst the utility companies had experienced," Phillips said.

Then a week before the official start of winter on Dec. 22, eastern Canada got pummelled by 20-30 centimetres of snow generally, with up to 60 cms. in London, Ont., and 50 in the Ottawa Valley and Quebec.

Number four on the list was a hot, stick tropical summer in the Prairies, primarily due to standing water left by the seventh wettest spring on record for the region.

From Calgary to Regina to Winnipeg, "it was a scorcher," said Phillips.

On July 28, Carmen, Man. reached a humidex of 53 - a national record which broke the record of 52 in Phillips' hometown of Windsor, Ont., which he called the humidity capital of Canada.

A hot, dry summer in southern Ontario with idyllic weekend weather took fifth place on the list.

The number of days above 30 degrees ranged between 20 and 30 - two to three times the normal. Toronto had only five wet days. In most cases, the rainfall was a mere sprinkle.

But while most city dwellers soaked up the rays, many farmers watched their crops wither.

"Farmers had planted record corn and they were seeing corn cobs wilting in front of them," said Phillips.

"There were watering bans, wildfire bans, campfire bans (and) at times, stressful to a lot of people."

On the other hand, fruit and grape growers in Niagara were delighted by the abundant sunshine and disease-free conditions.

Hurricane Noel, the most powerful of the season's 15 named storms to hit Atlantic Canada in 2007, occupied number six on the list.

However, by the time the storm raced into Canada in early November, said Phillips, It was really "Storm Noel" since it lacked tropical characteristics and had become a leftover remnant.

However, the sprawling system dumped heavy rain across Atlantic Canada and caused property damage and widespread power outages.

Number seven on the list was falling water levels in the Great Lakes.

Lake Superior set a record for its lowest water level in a September since measurements began in 1900. Lower water levels on the lakes forced freighters to lighten their loads in order to navigate safely.

The lack of winter weather at the start of 2007 was eighth on Phillips' list.

At the halfway point of the season, a persistent flow of warmth from the south and west left the ground in Eastern Canada soft, lakes and rivers free of ice and leaves hanging from trees. Winter eventually arrived in the second half of January to end the longest delay of winter weather in eastern Canadian history.

The most active summer for severe weather on the Prairies was ninth on the Environment Canada list.

Alberta, Saskatchewan and Manitoba recorded 410 severe weather events in the summer, eclipsing the previous high of 297 set only last year.

Rounding out the top 10 was Canada's first recorded F5 tornado on June 22 near Elie, Man., about 40 km. west of Winnipeg. The localized tornado, just 300 metres wide, tracked about 5.5 kilometres before lifting into the air.

Its top wind speed was estimated between 420 and 510 kilometres an hour as it sandblasted bark off trees.

© The Canadian Press, 2007