Young people around the world took to the streets on Friday to demand urgent action to avert disastrous climate change, in their largest protest since the start of the Covid-19 pandemic.

The strike takes place five weeks before the UN COP26 summit, which aims to secure more ambitious climate action from world leaders to drastically cut the greenhouse gas emissions heating the planet.

"The concentration of CO2 in the sky hasn't been this high for at least three million years," said Swedish activist...