TORONTO — Millions of people across Canada and around the globe are expected to turn out their lights Saturday evening to raise awareness about pollution and global warming in an initiative known as Earth Hour.

The World Wildlife Fund effort that began in Sydney, Australia last March 29 now appears to have caught the imagination of people in dozens of countries, nowhere more so than in this country.

"This has really just blown up across Canada,'' said Tara Wood, spokeswoman for the fund in Canada.

"Canada is really going to be the shining star in this global effort.''

Initially, the fund's idea was to test the Canadian waters in one city -- Toronto -- to see how the effort should be rolled out in future years. That proved impossible.

"There was no way to control it once people got wind of this really cool lights-out event,'' Wood said.

"It's been truly phenomenal.''

What began as a simple attempt at bringing climate change down to the living-room level has snowballed, burying those who argue Earth Hour is mere tokenism that will do little to cut greenhouse gas emissions or that participating businesses are only interested in their cash registers.

More than 240,000 people and almost 18,000 businesses in countries as far-flung as Botswana, Vietnam and Denmark have all signed up as participants this year via a website groaning under the strain.

But the number of people marking the event that runs from 8 p.m. to 9 p.m. local time is expected to be far higher.

About 55,000 Canadians have registered, just behind the United States and ahead of Australia. But 70 per cent of Canadians polled recently said they planned to mark the hour.

Municipalities from Charlottetown and Ottawa to Toronto and Vancouver, from Corner Brook, Nfld., and Melfort, Sask., to Lasalle, Que., and Terrace, B.C., are all recognizing Earth Hour.

In all, about 150 communities across Canada have signed on.

In Hanover, Ont., Zoe Soper, 18, who has challenged fellow students to participate, said she planned to pull the power breaker to her home.

"It's a pretty small thing to just get people to turn off their lights for an hour,'' Soper said. "Hopefully it will make people more aware of the issues surrounding energy waste.''

Cafe Koi in Calgary will attempt to operate without electricity for the entire evening.

Owner Philip Wong said a special menu is in the works that will include food that can be prepared beforehand or without electricity and served by candlelight.

"We'll try to operate as normally as possible,'' Wong said.

In Toronto, the lights will go out at City Hall and the focus will be on an acoustic concert outside featuring Nelly Furtado.

Ontario, which would usually use between 16,000 and 17,000 megawatts of power on Saturday evening, is forecasting a drop of about 800 megawatts -- almost five per cent -- during Earth Hour.

That's more than the dip that occurs during the moments of silence each Remembrance Day, said Terry Young, spokesman for the Independent Electricity System Operator in Ontario.

More important than just saving power for an hour, Wood said, is getting people to think about what they can do to help fight climate change -- whether it's by turning off lights, washing clothes in cold water or taking public transit.

"Turning off your lights doesn't have the huge energy savings with it, but what it does do is show how individual acts add up to make a big difference.''

Last year, about two million people and businesses in Sydney took part, pushing down demand for power in the city by 10 per cent -- the equivalent of turning off 50,000 cars for an hour, World Wildlife Fund said.