Students, union members and politicians were among thousands of people protesting Saturday across Quebec to demand action on climate change.

The diverse groups shared a message: They say governments, both domestic and abroad, are not doing enough to combat human-caused changes to the climate.

Three groups of demonstrators — one from Place des Festivals, one from Parc Laurier and one from Parc La Fontaine — converged at the foot of Mount Royal on Saturday afternoon.

The march took place as the island of Montreal was under a state of emergency due to the risk of flooding on the western and northern parts of the city.

It is the second time in three years the province has faced serious flooding, which leading scientists in the province blame in part on climate change.

"We are in the middle of a global humanitarian and ecological disaster," said Ben Clarkson, a spokesperson for the citizens' group La Planète s'invite au Parlement.

A protester hypes up those gathered at Place des Festivals ahead of their march to Mount Royal. (CBC)

He said we must move to a "zero-carbon society" as quickly as possible and stop extracting and burning fossil fuels.

Louis Couillard said protesting helped him cope with the anxiety he feels for the future of the planet.

"It's not too late now, and we want the population to understand that it is not too late. We can still solve the climate crisis," he said.

Quebec's largest unions took part in similar marches in Sherbrooke, Trois-Rivières, Rimouski, Rouyn-Noranda, Alma, Gaspé, Mont-Laurier and Ottawa.

"We want to make sure that the government, all the people making the decisions, stop putting their heads in the sand," said Anne Dionne, a member of the Centrale des syndicats de Québec's executive council and who was at the Montreal protest.

Members of the three provincial opposition parties — the Quebec Liberals, the Parti Québécois and Quebec Solidaire — also marched in the Montreal protest.

Quebec Liberal Party interim leader Pierre Arcand was one of the politicians at the Montreal demonstration. Members of the Parti Québécois and Québec Solidaire also took part. (CBC)

"We are here to support the fight against climate change because we feel very strongly that this is something that people should care about," said interim Liberal leader Pierre Arcand.

He said Quebec's carbon market has successfully limited greenhouse gas emissions, adding the province could further reduce its fossil-fuel consumption with the help of innovation from the private sector.

The march was the latest of several student-led demonstrations in Quebec to demand action on climate change, and capped off Earth Week.