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Extreme weather and climate change

Climate experts believe extreme weather events could be connected to global warming trends As flooding recedes in Squamish and Pemberton, and the human and economic toll of a record October rainstorm is assessed, the question is on everyone’s li

Climate experts believe extreme weather events could be connected to global warming trends

As flooding recedes in Squamish and Pemberton, and the human and economic toll of a record October rainstorm is assessed, the question is on everyone’s lips – what’s going on with the weather?

In the past year, B.C.’s weather has bounced from one extreme to another. A late start to the ski season on the coast was off-set by a near-record snowfall on Christmas Day.

In February, a sudden wind storm gusted in excess of 150 km/h, trapping more than 1,000 people on chairlifts and in lodges, and knocking down hundreds of trees in Whistler. While the winds will gust that high in the alpine occasionally, it was the strongest wind that many had seen on the lower mountain and in the valley in at least 20 years.

Throughout the winter, an unstable snowpack east of the coast range resulted in a record 24 avalanche deaths in the province.

This summer’s record drought conditions in the Interior resulted in the worst wildfires in generations, destroying more than 300 homes. It surpassed the Quebec ice storm of 1998 as the most expensive natural disaster in Canadian history, costing more than half a billion dollars in damages, fire fighting costs, and disaster relief.

Areas around B.C., including Squamish and Pemberton, posted record high temperatures in early October.

The recent record breaking rains in the Sea to Sky region, delivered by a relatively common weather phenomenon known as the "Pineapple Express" are being referred to as a 100-year-storm by meteorologists.

In four days, the Squamish area received about 369 millimetres of rain. By way of comparison, the average rainfall for Squamish for the entire month of October is 279 mm.

The flooding washed out bridges, caused rivers to jump their banks, and forced more than 800 people to evacuate their homes. At press time, there were two deaths, and two people still missing after a bridge to the south of Pemberton was washed away.

The province is estimating that the damages will total more than $20 million.

Taken together, the recent extreme weather events to hit B.C. make 2003 a most unusual year, to say the least.

If climate experts are correct, however, then B.C. should brace itself for more unusual years in the future.

"It’s hard to say that individual storm events or drought events are happening because of global warming, but there are a couple of things that we can say," explains Stewart Cohen, a scientist with the Adaptation and Impacts Research Group at Environment Canada, and a Senior Associate with the Sustainable Research Institute at the University of British Columbia. Cohen was also the co-ordinating lead author of the North American chapter in the 2001 UN-sponsored Intergovernmental Panel on Climate Change (IPCC) report titled Climate Change 2001: Impacts, Adaptation and Vulnerability.

"One thing we can say is that the current climate is no longer 100 per cent natural, and hasn’t been for a number of years."

According to Cohen, the recent extreme weather events to take place in B.C. are consistent with the projections made in the 2001 IPCC report. Among other things, the report predicted that there will be an increase in climate variability and in some extreme events.

According to the IPCC, "Models project that increasing atmospheric concentrations of greenhouse gases will result in changes in daily, seasonal, inter-annual and decadal variability."

That means greater fluctuations in winter and summer temperatures, wetter climates in some regions, drier climates in others, and the possibility of more El Nino-like conditions. The extreme events include more hot days, heat waves, heavy precipitation events, and fewer cold days.

"Many of these projected changes would lead to increased risks of floods and droughts in many regions and predominantly adverse impacts on ecological systems, socio-economic sectors, and human health," wrote the IPCC.

Cohen is cautious about linking recent events to climate change, but said the connection can’t be ruled out either. Generally climate scientists look at trends as they emerge over a period of years and decades, comparing the data with seasonal averages.

"What we could find is that today’s peak day falls in tomorrow’s upper third day, an increase in the type of event we call extreme. Those one-of-a-kind events won’t be so one-of-a-kind anymore," said Cohen.

There is an ongoing debate among climatologists as to how much climate change is natural and how much is man-made. Scientists do agree that carbon dioxide concentrations in the atmosphere have risen from about 290 parts per million to 370 ppm in the past hundred years, but many believe that part of that trend, as well as general global warming trends that have seen a break-up of glaciers on both poles in recent years, is natural.

Rather than debate the causes and solutions, Cohen’s job is to assess the risks for communities and recommend ways to mitigate the effects of extreme weather events.

"The challenge is how do you incorporate these extremes into design… by looking into the future," said Cohen. "If droughts continue in the Okanagan, what does that mean for water supplies and irrigation? What does it mean for reservoir management and making sure there is enough water left over for the fish?

"For Squamish and Whistler and Pemberton, what does it mean for the drainage and diking. Do we need to change the location of roads, or build different kinds of bridges?"

There is an extra cost to anticipating extreme weather events, says Cohen, and every community needs to do a cost-benefit analysis.

"You can’t predict if and when the next extreme storm or drought is coming, but you can plan for when it does," said Cohen. "If you believe that the increase in greenhouse gases has impacted our climate and made the weather more extreme, then you need to expect that more events are on the way."

The David Suzuki Foundation takes a slightly different view on mitigating the impacts of global warming and climate change, putting the onus on individuals to change their habits to reduce greenhouse gas emissions.

"What it says to us, if these are the kinds of weather events that we can expect from higher concentrations of carbon dioxide, then we really need to look at ourselves, and look at ways to resource our dependence on things like fossil fuels," said Morah Carter, the director of the climate change program at the David Suzuki Foundation.

"Absolutely (this summer’s events) should be a wake-up call to people and governments. As far as we’re concerned the debate (on climate change) is over – Canada has signed the Kyoto Protocol, and we should be implementing these cuts as part of international obligations."

According to Carter, governments in B.C. and Alberta opposed ratifying Kyoto on the basis that the costs would scare away industry and investment, while increasing burdens for taxpayers.

"The provinces need to get on side because extreme weather events are costing us money, too," said Carter.

The concept of global warming as a result of greenhouse gases is now generally accepted by most governments, most science institutions, and by economic groups like the insurance industry, Carter says. Actions are being taken on a national and global scale, but individuals can also make a difference.

Last year the David Suzuki launched the Nature Challenge, with 10 suggestions on how people can work to conserve nature in their daily routines. They also released a toolkit to help communities battle urban sprawl, which is a major contributor to greenhouse gas emissions.

"People are coming to us looking for information like never before," said Carter. "Definitely the drought of this summer brought global warming home to people like never before, and they want to know more about it. They also want to know what they can do, and are more open to ideas, and to changes."