About 100 people gathered at the top of Mount Royal Saturday to paint a 60-foot-wide mural on the mountain's main lookout to demand action in the fight against climate change.

The "artistic civil disobedience action" was organized by Greenpeace to "send out an inspiring and beautiful message to our society," said Isabelle L'Héritier, a spokesperson for the environmental group.

They expected to complete the mural, designed by Meky Ottawa, an Atikamekw artist from Manawan, Que., in a couple hours.

But due to the number of people at the lookout on the beautiful fall day, they were able to finish it in about 20 minutes.

L'Héritier said climate change is not taking up enough space in the federal election campaign, nor in the actions of politicians, so the mural is a way to increase pressure on political institutions to act.

About 100 people helped paint the mural. (Verity Stevenson/CBC)

Starting with chalk outlines, volunteers then painted the different sections of the circular mural with non-toxic paint. So many people wanted to participate that they decided to paint a white border around the mural once it was completed.

"The design is to give hope to the people that see it, and it is open to interpretation as well, because there is a lot of symbols and colours," said Ottawa.

She said the general theme for the artwork is to encourage the protection of the Earth.

Greenpeace informed the city that the action was taking place ahead of time, but they did not get a permit.

The group said the paint was made in Quebec and will wash away with rain.

Frannie Napier-Keeling was one of the volunteers who helped paint the mural.

She said she has been participating in the student strikes in Montreal demanding action on climate change.

"It's peaceful, it's fun, it's for everyone and I think it's a really good way to get everyone into the movement," she said of the mural.