Thousands of people descended on the seat of political power in the province Friday for what one of the organizers hopes will be "Canada's largest climate strike ever" to demand immediate action on climate change.

Thousands more are taking to the streets across the GTA as part of weeklong protests inspired by Swedish activist, Greta Thunberg's #FridaysForFuture movement.

On Friday, 85 cities across Canada are holding climate strikes.

Grace King, a student and organizer with Climate Justice Toronto, said upwards of 10,000 had been expected to gather at Queen's Park. Images from the scene suggest that crowd could be larger.

"Youth are rising from coast to coast to coast. We stand in solidarity with people from St. John's to Victoria," King told CBC Toronto.

"I think this movement has grown beyond any of our expectations."

Protesters gather outside the Ontario Legislature for the climate strike, in Toronto on Friday. (Chris Young/The Canadian Press)

Roy Bateman, a 13-year-old student, addressed the crowd under sunny skies and accused governments of not making environmental policy a priority.

"We need to let them know that they have to shift their priorities and take quick, decisive and meaningful climate action," Bateman said. "Your participation in this event is a big step in that direction."

After a late-morning rally, attendees chanting slogans and carrying homemade signs began marching south from Queen's Park.

And so the Climate Strike march begins! <a href="https://twitter.com/CBCToronto?ref_src=twsrc%5Etfw">@CBCToronto</a> <a href="https://twitter.com/hashtag/climatestriketo?src=hash&ref_src=twsrc%5Etfw">#climatestriketo</a> <a href="https://t.co/Tg3cF8r4o1">pic.twitter.com/Tg3cF8r4o1</a> —@anastasiaandric

Alienor Rougeot of Toronto's chapter of Fridays for Future and a co-organizer of the city's event, said she and her fellow activists are inspired by Thunberg's emotional pleas to world leaders for urgent action.

"I know that for myself I am angry and I am outraged at the injustice that keeps happening," Rougeot told CBC Radio's Metro Morning on Friday.

"So I think today our message is going to be partly about the fact that you're allowed to be outraged, you should be outraged, and it's only that that's going to save us."

Alienor Rougeot is seen outside Queen's Park on Friday, ahead of the climate strike. (Salma Ibrahim/CBC)

The event at Queen's Park preceded a march through downtown, and speakers from a diverse array of environmental groups, migrant support agencies, Indigenous communities and social justice advocates, among others, spoke to the gathered crowd. Rougeot said the goal of the event is to educate attendees, as a federal election approaches, how other issues such as health care, transit and affordability are all deeply connected to climate change.

"Why are we never talking about these, not as climate change as one of the issues that you should be concerned about, but educate people on the fact that your health care and your house insurance, for example, they heavily depend on the risk of climate change," Rougeot said.

Given the chance, she said, she would challenge federal and provincial politicians to consider how the province and country will meet emissions-reductions targets.

Ontario Environment Minister Jeff Yurek issued a statement Friday as the rally got underway, saying he "would like to recognize all the young Ontarians who are making their voices heard on the serious issue of climate change."

He then went on to highlight provincial measures to address climate change, including proposed new rules for industrial polluters and landfill-diversion efforts.

"We are committed to taking meaningful action on climate change by implementing effective and affordable measures to reduce our province's emissions and support Ontarians as they look to do their share in helping to protect and preserve the environment," Yurek said.

Dianne Saxe, Ontario's former environmental watchdog, disagreed with that characterization. She said the Tories have become an "obstacle" to the climate change progress during a speech at the rally.

Saxe's job was eliminated earlier this year when the Ford government folded her office's duties into those of the auditor general.

Liberal Leader Justin Trudeau, who attended Montreal's climate strike and met with Thunberg earlier in the day, pledged Friday that should his party form the next federal government, it would set a goal of planting two billion trees over ten years. In a statement, he criticized Ontario's PC government for cancelling a tree-planting program earlier this year that had planted some 27 million trees in the province since 2008.

"When Doug Ford took an axe to Ontario's tree planting programs and the seasonal jobs it supported, we took a stand," Trudeau said. "We can either go back to the Harper years, when the Conservatives did nothing about climate change — or fight for a better future. I'm for moving forward."

Meanwhile, here's what you can expect in the GTA to mark Friday's climate action.

Climate strike participants started arriving at Queen's Park early Friday morning. (Salma Ibrahim/CBC)

Toronto's biggest march at Queen's Park

The city's biggest strike took place outside Queen's Park.

Just after 12:30 p.m., the group began marching east on Wellesley Street and was expected to continue south on Bay, west on Queen Street and back up University Avenue to Queen's Park.

There was also a pre-strike art demonstration at 10 a.m. that saw Greenpeace Canada, local groups and volunteers paint large murals along the march route. A concert will end the event, with Barenaked Ladies bassist Jim Creegan making an appearance, along with other musical acts.

Various speakers are in attendance, including numerous Indigenous activists such as Cody Looking Horse, a young activist who was part of the Dakota Access Pipeline protests at Standing Rock.

Schools taking part

Schools around the GTA were expecting some students to leave class to participate in the strike.

On the bus to cover the climate strike in Toronto. Met these great kids who are also on their way! <a href="https://twitter.com/hashtag/climatestriketoronto?src=hash&ref_src=twsrc%5Etfw">#climatestriketoronto</a> <a href="https://twitter.com/CBCNews?ref_src=twsrc%5Etfw">@CBCNews</a> <a href="https://t.co/T6cnMN0qB7">pic.twitter.com/T6cnMN0qB7</a> —@NebulousNikki

The Leap Chapter of the University of Toronto planned a mass student walkout. They met outside the St. George Street entrance to join other students at the main rally at Queen's Park.

Students with the Toronto District School Board (TDSB) and the Toronto Catholic District School Board (TCDSB) were expected to participate and asked their schools to avoid scheduling tests and other assessments today.

Strikes also taking place across GTA

Scarborough is hosting its own climate strike at Albert Campbell Square, near Brimley Road and Ellesmere Road, that is set to begin at 1 p.m.

The Mississauga Climate Action group has organized an event in Celebration Square, near Mississauga's City Hall, at 12:30 p.m.

Major companies closing their doors

A number of companies shut their doors in solidarity with the climate strike.

Mountain Equipment Co-op closed its Canadian stores until 5 p.m. local time, saying they want to provide their staff the opportunity to join the strike.

Nicole McRonney-Apaw, Influencer Relations at Lush Cosmetics - which closed its stores so staff could participate in the climate strikes. (Anastasia Andric/CBC)

Lush Cosmetics North America shut down all operations for the day.

And Patagonia, the outdoor clothing maker, also stopped its operations and encouraging customers to support climate striking students.