V i v i a n  S o n g
Freelance writer
Freelance writer
Weather vs climate

Published in the Toronto Sun and Sun Media papers April, 2009.

This column is long overdue.

In uncharacteristic fashion, I'm launching an offensive against readers who, in smug condescension, like to point to one-off weather incidents which dump 25 cm of snow in their neighbourhood in April as proof the world is actually cooling.

Or those readers who use record-breaking statistics of cold winter snaps as ammunition that climate change is a hoax.

Consider it a service, nay a public service announcement, that I am performing in teaching everyone that there is a significant, nay, monumental difference between weather and climate.

The same goes for those who attribute stretches of heat waves in the summer to climate change -- it's just inaccurate.

I turn to the always loquacious and perhaps most passionate climatologist in Canada, David Phillips, for clarification. He expresses relief at my endeavour.

"Often the public blurs the distinction between the two," says the Environment Canada spokesman. "But they're very different and at times it's frustrating."

Weather is what happens outside your window, he explains. "You can see weather but you can't see climate."

When scientists use the term "climate," they're referring to long-term averages of weather patterns, measured not in years but decades.

Climatologists most often use 30-year record periods to measure weather patterns in broad regional scales.

"I'm a little bit like an historian and a futurist," Phillips says. "I'm interested in what the situation will be like 100 years from now, but I'm also interested in what the climate was like 100 years ago, for our ancestors."

Meteorologists, meanwhile, work in immediacy.

"Weather is what you feel," explains Peter Kimbell, a warning preparedness meteorologist at Environment Canada. "I forecast weather warnings on a short-term basis, the next few hours or the next few days . . . the difference is quite significant."

My attempt to elucidate the difference is to show people that, no, you cannot volley a record-breaking cold snap this winter or heat wave last summer into a climate change-related discussion. Climate models are measured in larger scales than one day, or even one season.

And while I am perfectly aware that the planet has gone through ice ages, cooling periods and heat waves before, what's happening now is exacerbated by the pace at which the planet is changing.

"What's irrefutable, is that every corner of the world is warming up and that speeds of warming have increased in recent years," Phillips says.

What's less clear is the correlation between climate change and extreme weather patterns, he says.

While long-term record-keeping of temperatures and precipitation make for a rich climatic history in Canada, records of extreme weather incidents are shorter and incomplete.

But Canada can expect to see an increasing frequency of "high impact" incidents, Phillips says.

Warmer temperatures mean more moisture and evaporation -- fuel for storm activity.

Expect more tornadoes, drought and flash flooding, extreme weather patterns that afflict the U.S. which we're likely to inherit.

But it's not all doom and gloom.

Canada is the snowiest country in the world and the second coldest country after Russia. Gentler winters would be a welcome reprieve for Canadians. The problem, he says, is what's likely to happen beyond the first few generations.

A warmer climate will also bring with it more "wildcards" in the weather system, Phillips says, or increased variability.

For example, 2007 was one of the driest years on record, while the following year was the wettest on record. Two years ago we got little snow precipitation, while 2008 goes down as the third snowiest year in history.

"One of the things climatologists used to say is that the last 100 years of weather data will be the story of our future since weather repeats itself," he says. "But I don't believe that anymore. Changes are happening so rapidly."

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The difference between weather and climate is that weather consists of the short-term (minutes to months) changes in the atmosphere.

WEATHER: "Weather is basically the way the atmosphere is behavingly with respect to its effects upon life and human activities. The difference between weather and climate is that weather consists of the short-term (minutes to months) changes in the atmosphere. Most people think of weather in terms of temperature, humidity, precipitation, cloudiness, brightness, visibility, wind and atmospheric pressure, as in high and low pressure."

-- Definitions according to NASA

Some scientists define climate as the average weather for a particular region and time period, usually taken over 30 years.

CLIMATE: "Climate is the description of the long-term pattern of weather in a particular area. Some scientists define climate as the average weather for a particular region and time period, usually taken over 30 years. It's really an average pattern of weather for a particular region. When scientists talk about climate, they're looking at averages of precipitation, temperature, humidity, sunshine, wind velocity, phenomena such as fog, frost, and hailstorms, and other measures of the weather that occur over a long period in a particular place."

-- Definitions according to NASA

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