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Thousands of people filled the streets of Toronto on Sunday to call on Canada to shift its focus away from fossil fuels toward an economy that embraces renewable energy.

Labor unions, student groups, indigenous communities, and environmentalists joined forces for the Jobs, Justice and Climate march, which activists called the most diverse climate mobilization in Canadian history.

The rally was timed to bring attention to the cause ahead of this week's Climate Summit of the Americas in Toronto, this fall's Canadian federal election, and the highly-anticipated UN Paris climate talks in November, which aim to bring together world leaders in legally-binding climate change solutions.

Celebrities including Jane Fonda, environmentalist David Suzuki, and author Naomi Klein kicked off the rally in front of the Ontario provincial legislature.

Organizers said as many as 10,000 people participated in the event; police described the attendance as "large," but told VICE News they didn't do a head count.

Labor leaders said the march marked the first time the labor movement in Canada has allied with indigenous and environmental activists to combat climate change.

"In some respects, labor has been a road block because we're very concerned about jobs in the short term, and now we're beginning to look at the question from more of a longer term perspective," Sid Ryan, president of the left-leaning Ontario Federation of Labor, told VICE News.

In the next 15-to-20 years, if we start weaning ourselves off fossil fuels and start moving into solar and wind, "those jobs are good paying jobs, really good paying jobs," he argued.

Ryan called Canada's Conservative Prime Minister Stephen Harper "an impediment" to a renewable energy economy. "So we actually need to move beyond his thinking to a new government with new ideas who are willing to take a look at the new technologies and this new movement," he said.

Melina Laboucan-Massimo of Greenpeace and the Lubicon Cree Nation in the Alberta oil sands told VICE News she attended the march to start a conversation about what a renewable energy economy would look like in Canada.

Her First Nation's traditional territory is surrounded by resource extraction that has had detrimental effects on her community, she said. In April 2011, a pipeline burst 30 kilometres away, spilling 4.5 million litres of oil across Lubicon Cree territory.

"I remember doing a fly over just because we needed to take pictures from the air because it was so big," Laboucan-Massimo told VICE News. "And it was just, you could just smell the fumes, and my family was texting me saying, we can't breathe, our eyes are burning, our stomachs are turning, we feel nauseous."

She called her community "economic hostages" of Alberta resource extraction. "What I'm planning to do this summer is actually implement a solar project back home in my home community where my family lives in the tar sands," she said.

Migrant rights groups showed up to highlight the often-overlooked relationship between climate change and immigration policies. Syed Hassan, an organizer with End Immigration Detention, told VICE News it's a discussion that's necessary to address the full range of ways humans are impacted by fluctuating temperatures.

"One of climate change's most dramatic impacts are on racialized people in the global south. Floods, famines, droughts," he said. "People are dying and being forced to migrate to places like North America where they arrive as immigrants with no rights, living in precarious conditions. Being part of the climate movement means ensuring that people can move freely with dignity."

March about to start --indigenous and migrant rights groups at the front. — Rachel Browne (@rp_browne)July 5, 2015

And having migrant and labour organizations at the march signals how the climate movement is becoming more inclusive, Hassan added. "The environmental movement has for a very long time been a white movement. Now, racialized people have been forming their movements, getting organized and the mainstream climate movement has slowly started to see the importance of joining forces. It's an important time," he said.

"The economy right now is not working for working people,"Ryan, president of the Ontario Federation of Labor, told VICE News. "We've got a golden opportunity now that the price of oil is dropping around the world. And there's not all that tremendous pressure here in Canada to keep the oil sands chugging along. Unfortunately we've lost thousands of jobs there, but at the same time have slowed down production, and that gives us an opportunity to look at alternatives. And that's where we're at."

Later this week, the Ontario provincial government will host a Climate Summit of the Americas in Toronto — just before the Pan Am and Parapan Am Games — where Al Gore and former President of Mexico Felipe Calderón are expected to speak on climate change.

The summit will aim to find ways to reduce greenhouse gas emissions across the Americas and invest in low carbon energy options.