Greta Thunberg did not mince words at a climate change march on Friday, condemning her parents' generation for asking young people to "clean up" the environment.

The 17-year-old Swedish climate activist, who has made a number of high-profile appearances around the globe to promote climate activism, addressed a crowd on the College Green in Bristol, England, where she admonished the political class and warned that change was coming "whether you like it or not."

"I will not be silent while the world is on fire. Will you?" Thunberg said to the crowd of more than 15,000 people who attended Bristol's Youth Strike 4 Climate. "Once again, they sweep their mess under the rug for us young people, for their children, to clean up for them."

The event was moved from London after organizers said they needed a larger space to hold the march. The crowd chanted "Greta" as she took the stage and celebrated the news that plans to expand an airport in the United Kingdom were canceled after climate change protests.

"Those in power, they are failing us, but we will not back down," Thunberg continued. "And if you feel threatened by that, then I have some very bad news for you. We will not be silent because we are the change, and change is coming whether you like it or not."

Thunberg has made numerous controversial statements when speaking on the issue of climate, and the environmentalist apologized in December for telling world leaders they would be put "up against the wall."