Protests over climate change in 139 countries

Millions of people around the world walked out of their schools and workplaces Friday to demand urgent action on climate change.

The global climate strikes, which are taking place in more than 150 countries, were scheduled ahead of the opening of the United Nations General Assembly and the Climate Action Summit on September 23.

The protests have been organized by young people around the world who are part of the "Fridays for Future" campaign, which has seen students walk out of their schools on Fridays to demand their political leaders take urgent action to address climate change.

Climate activist Greta Thunberg participated in the protests in New York City, where 1.1 million students have been given permission to skip school to join in.