The event was described as Belgium's biggest climate march ever, with police estimating slightly bigger crowds than a similar demonstration last month. Trains from across the nation were so clogged that thousands of people didn't make the march in time.

Some 35,000 students in Belgium skipped classes Thursday to take their demands for urgent action to prevent global warming to the streets.

"Young people have set a good example," protester Henny Claassen said amid raised banners urging better renewable energy use and improved air quality. "This is for our children, for our grandchildren, and to send a message to politicians."

Even though the direct impact on Belgian politics was likely to be small since the country currently is led by a caretaker government, the demonstrations have pushed the issue of climate change up the agenda as parties prepare for national and European Union elections in May.

The march ended at the headquarters of the European Union. The 28-nation bloc has been at the vanguard of global efforts to counter climate change but still came in for the protesters' criticism.

"Society as a whole could do a lot more because they're saying 'Yes, we're doing a lot,' but they're doing not that much. They could do a lot more," demonstrator Pieter Van Der Donckt said.

Citizen activism on climate change Sunday was not limited to Belgium.

Thousands of people made human chains or held other climate events around France.

In Paris, there was a debate inspired by a recent petition for legal action to force the government to set more ambitious goals for reducing carbon emissions that create global warming.

President Emmanuel Macron sees himself as a climate crusader, but suffered a serious setback when fuel tax increases meant to help wean France off fossil fuels backfired dramatically, unleashing the yellow vest protests now in their third month.