Around 45,000 climate campaigners marched in Paris Saturday to condemn what they called the French government's "inaction" on climate change, according to a media estimate.
Organisers of the march through the centre of the city, which coincided with "yellow vests" riots in the west, estimated that 107,000 people took part while the police put the figure at 36,000.
Organisers said more than 350,000 people turned out to march in 220 towns and cities across France.
"Macron, you're screwed: the pandas are in the street," said one placard at the Paris demonstration, addressing French president Emmanuel Macron.
"We are here to demonstrate against the inaction on climate change... and against the multi-billionaires in their ivory towers," 18-year-old drama student Pierre-Loup Meriaux told AFP.
Many of those present were young people, some of whom had already marched the previous day in a youth protest for climate change action.
On Friday, tens of thousands of young people took part in the Paris edition of the global student climate demonstration inspired by 16-year-old Swedish campaigner Greta Thunberg.
They were joining marches in cities across the world Friday, as hundreds of thousands of young people skipped school to join the protests.