According to organizers, over half a million people are participating in the march, but authorities have yet to come out with any figure, according to the news agency AP.
Greta Thunberg was forced to leave the demonstration for security reasons, when all the protesters and journalists who wanted to catch a glimpse of her became too high. She was taken to safety behind the stage at the government buildings Nuevos Ministerios, where she later gave a short speech to the protesters.
The protesters want to put pressure on world leaders and make them work more actively to achieve the climate goals. Representatives for nearly 200 countries are in place during COP25.
"Just eight years to 1.5 degrees - how dare you?" It said on a banner that two activists hung on a bridge to public cheer, according to AP.