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

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

The events were organized by, 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.

One of the organizers of the rallies, Joanna Dafoe, called the day "an incredible success."

"Most importantly for our country, Canada was the second-largest participant," she told CTV News Channel on Saturday evening.

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

One of the largest Canadian events was expected to take place in front of 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.

People in 181 countries were 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, a crowd of 350 bicyclists were expected to peddle through the city together. In Victoria, a church rang its bells 350 times over the course of an hour to mark the number.

At the West Edmonton Mall, a group danced to Michael Jackson's "Thriller" in costume. At another Toronto event, a group of people dressed in black, chanting "tick, tick, tick" assembled at a public square to symbolize a ticking time bomb.

The gatherings 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 included 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 took part by writing "350" in chalk on a mountain.