Green campaigner Great Thunberg rallied in Sweden on Friday telling a crowd that she feared the Cop26 environmental summit would end in failure, as other rallies were staged across several continents.
Protests were staged in more than 500 locations, including Uganda, Bangladesh, India and Germany.
Ms Thunberg was speaking in Sweden at an event organised by Fridays for Future, the climate change protest movement that rocketed her to international fame in 2018.
Asked if she believes Cop26 can deliver the necessary action, she said: “As it looks now, no, I don’t think so.”
Up to 2,000 banner-waving climate activists rallied outside the Swiss Parliament on Friday in support of a Global Climate Strike that youth movement Fridays for Future had called for before the UN climate summit.
“There is a window time in which we can change this, so we’re going to do everything we can in that period of time to make sure that we push in the right direction,” Ms Thunberg said.
“We are watching … We are not going to let them get away with more talking and not doing anything and pretending the situation is under control.
“Today, October 22, people are striking all around the world for climate to uproot the system that needs to be done now. People around the world stand together in solidarity for a common thing.
“We stand in solidarity with people abroad, people who live on the front lines of the climate crisis and who are affected first and hardest, and who are struggling in a fight against the climate crisis.”
Thousands of people also rallied at Berlin’s Brandenburg Gate, carrying banners featuring slogans such as “Act now or swim later” and “Don’t melt our future".
Many called on the next German government to place greater emphasis on tackling climate change. Three parties, including the environmentalist Greens, are negotiating to form a coalition government.
In the Philippines, climate activist Mitzi Jonelle Tan said: “It’s so important that a lot of us here, from the global south that are the countries most affected by the climate crisis are here today because we wanted to bring the voices of the most affected to the biggest strikes and that’s here.”
In Uganda, another climate activist, Edwin Namakanga, said: “We are experiencing landslides in the eastern part of Uganda and then severe catastrophic floods, whereby they have left many homes destroyed. People are dying and then also … there is food scarcity.”