Climate activists vandalise glass safeguarding Gustav Klimt's painting in Vienna

UK organizers decided to hand the day over to civic groups in an acknowledgement of how young campaigners like Vanessa Nakate of Uganda and Greta Thunberg of Sweden have raised public understanding of climate change, and a nod to their stance that today's youth must live with consequences of state decisions.

"We're expecting lots of people to come and join us in the streets and not only youth but also adults supporting youth, and adults that want climate action,” said Isabelle Axelsson, 20, an activist with Thunberg’s climate movement Fridays For Future, which is organizing the march.

The COP26 talks in Glasgow aimed to secure enough national promises to cut greenhouse gas emissions - mainly from fossil fuels - to keep the rise in the average global temperature to 1.5 degrees Celsius. Crossing that threshold could trigger a cascading climate crisis, scientists say.

The COP26 summit has so far yielded deals to phase out coal, reduce deforestation and curb methane, but a clear picture has yet to emerge on what these voluntary initiatives would add up to in terms of moderating temperature rises.