VANCOUVER – Thousands of people joined teen activist Greta Thunberg in a climate march in downtown Vancouver Friday. 

The Swedish climate activist participated in the rally that began at 11 a.m. outside the Vancouver Art Gallery, run by a local youth-led organization, Sustainabiliteens.

After a march around downtown Vancouver, Thunberg made remarks in front of the crowd, commending the work of local activist Severn Cullis-Suzuki, daughter of David Suzuki. Cullis-Suzuki spoke at the 1992 Earth Summit in Rio de Janeiro about the risk of climate crisis.

"If people would have listened back then, the world would be a completely different place than it is today," Thunberg said on the steps of the art gallery Friday. 

"But the world ignored her. The world leaders continue to choose to look away from this crisis even today … If world leaders would have started to take action back then when this crisis became known to them, then imagine the sufferings that could have been prevented."

In her speech, Thunberg said youth are taking action around the world. 

"The people in power need to start to realize what they are doing to future generations," she said. "If the adults really loved us they would at least do everything they possibly could to make sure we have a safe future. A future to look forward to."

Towards the end of her remarks, Thunberg promised the action would not stop.

"We are not just some kids skipping school or some adults who are not going to work. We are a wave of change and together we are unstoppable," she said. 

"We will rise to the challenge and hold those responsible for this crisis accountable … if you feel threatened by that then I have some very bad news for you. This is just the beginning. We will continue. Because change is coming whether you like it or not." 

Vancouver police estimated on Twitter that 10,000 people were listening to Thunberg's speech.

Ahead of the march, Vancouver police warned there could be "major delays in the downtown core throughout the morning" because of the rally.

Local politicians including recently re-elected MP Jody Wilson-Raybould and Green Party Leader Elizabeth May attended the event. 

Ahead of the march, 15 youth announced their plans to sue the federal government, alleging it's contributed to climate change. The David Suzuki foundation is a partner in the case and says the plaintiffs each allege they have suffered specific injuries from climate change.

One teen told the crowd she has suffered from Lyme disease, while others said they have been impacted by wildfires and haven't been able to enjoy the outdoors. 

"We have demanded change and don't think enough has been taken, so we feel this is the best way," Ira Reinhart-Smith, one of the plaintiffs, told CTV News Vancouver. "This lawsuit will show the world how serious we are."

The allegations have not been tested in court and the federal government has not responded to the claims. 

For Naia Lee, who is part of the Sustainabiliteens' march-organizing group, Thunberg could help take local Vancouver climate rallies to the next level. 

"We've been focusing a lot on fighting for climate justice, fighting for Indigenous sovereignty, fighting for environmental rights as human rights so it's great that she's coming to amplify our messages like that," she told CTV News Vancouver. 

Sixteen-year-old Thunberg rose to global prominence by staging weekly climate strikes outside the parliament building in her native Sweden. Her demand for more aggressive action to combat climate change inspired the Fridays For Future movement, which has seen students around the world join in the weekly protests.

On Thursday, Thunberg posted a photo on Twitter showing that she had arrived in the city. 

"I reached the Pacific Ocean," her post said, with a photo of her that appears to have been taken from the seawall in Stanley Park. 

Thunberg has been in North America since late August, when she sailed across the Atlantic Ocean to attend the United Nations' Climate Action Summit.