Emma Thompson, Vivienne Westwood, Joel Plaskett march in climate change protests

Canadian musicians Joel Plaskett and Raffi, and actors such as Emma Thompson are throwing their support behind climate change marches around the world.

Plaskett, a rock musician from Nova Scotia, attended a demonstration in Halifax and posted a picture on Twitter.

Children's musician and songwriter Raffi used his account to raise awareness for the cause in general.

In London, hundreds of people were joined by British fashion designer Vivienne Westwood and actress Emma Thompson, known for her roles in the Harry Potter films and Saving Mr. Banks.

"This is our planet and we are in deep, grave danger," Thompson told Sky television.

In Paris, activists laid out more than 20,000 pairs of shoes in the Place de la République, including pairs donated by Westwood and French actress Marion Cotillard, among others.

The high heels, sandals and sneakers were meant to symbolize absent marchers after demonstrations were banned in the French capital following the Nov. 13 attacks in the city.

The international talks in Paris also coincide with the Canadian release of an HBO documentary on Dec. 3 called How to Change the World. The film tracks the evolution of the worldwide environmental organization Greenpeace from its humble beginnings in Vancouver, B.C.

"What it really speaks to is the fact that progress is only going to be made by individuals caring and doing something," said Bobbi Hunter, wife of the late Greenpeace co-founder Robert Hunter.

"That is really the message. It doesn't take a lot of people to make change. It can just be a small group of people but it's just the people."

The documentary made it to the Academy Awards' long list for Best Documentary.