Updated: Sat Oct. 24 2009 13:02:40

CTV.ca News Staff

Thousands of people in dozens of cities across Canada are expected to take part in a global day of action Saturday, to encourage world leaders to help stop climate change.

There are more than 150 events scheduled across Canada, in cities as big as Toronto and Montreal, to as small as Flin Flon, Man. and Wolfville, N.S.

One of the largest Canadian events is expected to be a rally at the provincial legislature in Toronto.

"We're expecting Queen's Park to be filled to the brim," Sharon Howarth, an environmental activist, said in an interview Saturday morning with CTV News Channel.

"Canadians are really on board, they understand the urgency," she said.

Canada has the largest number of events worldwide, behind the United States.

The events are organized by www.350.org, a group dedicated to reducing the amount of carbon dioxide in air to 350 parts per million. NASA scientist James Hansen identified the number as the safest limit for carbon dioxide levels in the air. The world is currently over that number, at 383 parts per million.

People in 181 countries are expected to participate in 5,200 events, urging world leaders to help stop climate change ahead of a December meeting in Copenhagen, Denmark where they will discuss the issue.

"This international day is to send a message to the international leaders to get a strong target at Copenhagen," said Howarth.

People across Canada will try to make themselves heard in different ways.

In Montreal, 350 people will ride their bikes in unison through the city.

In Victoria, a church will ring its bells 350 times in an hour to mark the number.

At the West Edmonton Mall, a group will be dancing to Michael Jackson's "Thriller" in costume.

In another Toronto event, a group of people dressed in black, chanting "tick, tick, tick" will assemble at a public square to symbolize a ticking time bomb.

The events kicked off in Australia where thousands of people formed a large "350" with their bodies in front of the famous Sydney opera house and held placards with the number on Bondi Beach.

Other worldwide events scheduled include setting alarm clocks to ring at the same time in Paris in order to "wake up" President Nicholas Sarkozy on climate change. People in Kabul are taking part by writing "350" in chalk on a mountain.