Friday's focus was on communities that have contributed little to greenhouse gas emissions, but are on the front lines of devastating climate threats including violent storms, rising seas and locust plagues.
In the Philippines, Mitzi Jonelle Tan, a 22-year-old Fridays for Future activist, said recent flooding had wiped out a local COVID-19 testing centre and caused a tree to fall on her home.
"I hate that it is a normal thing to experience these impacts. I hate that it is a normal thing that people are suffering – because they don't need to," she said.
Her government was failing to protect people from both climate change and the coronavirus. "They are still prioritising the rich over the poor, they are still not listening to the science," she said.
People in the global South were dying because of climate change, said 19-year-old Belgian activist Anuna De Wever ahead of a planned protest in a Brussels square.
"As one of the richest continents, we (Europeans) have the biggest responsibility to fight climate change in the most ambitious way possible."
Mya-Rose Craig, an 18-year-old Briton, travelled to the Arctic - one of the world's fastest warming regions - with Greenpeace to stage the most northerly protest on an ice floe.
In Germany, large numbers were scheduled to gather in Berlin and Bonn as well as Hamburg.
In the capital, where police had said they also expected 10,000, protesters cycled in groups to Brandenburg Gate. Hundreds sat in face masks, observing social distancing and chanting: "Strikes in school, university and companies. That is our answer to your politics".
Activists in Bogota, Colombia, said they would use the event to urge their government to ratify the Escazu Accord, enshrining protections for those working on environmental justice.
In Australia, thousands of students earlier took part in about 500 small gatherings and online protests, to demand investment in renewable energy and oppose funding for gas projects.
