1. “You had a future and so should we.”

Chants like that echoed around the world as millions of students took to the streets to demand action on climate change. More than 100,000 protested in Melbourne, in what organizers said was the largest climate action in Australia’s history. In New York City, where the 16-year-old activist Greta Thunberg spoke, the mayor’s office estimated the crowd swelled to at least 60,000.

We spoke to eight local leaders. Above, students in La Paz, Bolivia.

There was some action: Germany unveiled a $60 billion package of climate policies, and California and 23 other states sued the Trump administration in a fight over setting stricter rules on climate-warming tailpipe emissions.