At least 70,000 people braved cold and rain in Brussels to demand the Belgian government and the European Union increase their efforts to fight climate change Sunday, the Belgian capital's fourth climate rally in two months to attract at least 10,000 participants.

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 thousands of people didn't make the march in time.

Some 35,000 schoolchildren and 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."