Today, hundreds of thousands of children marched in dozens of countries around the world to send a clear, urgent message: governments should do more to tackle climate change now – not just with words and pledges, but with concrete steps.

A young protester marches in Berlin, Germany, to demand government action on climate change, March 15, 2019.

© 2019 Juliane Kippenberg/Human Rights Watch

What started with the protest of a single Swedish girl – then 15-year-old Greta Thunberg – has now grown into a global youth movement and perhaps the biggest “climate strike” in history.

At the Berlin march today, an estimated 20,000 children chanted and held up posters. Their signs urged “Stop coal” or simply “Act Now!” One poster read: “Fridays no school!? Climate change is much worse.”

I joined the march with my 11-year-old son and his friend and found myself in the midst of thousands of students, along with a few other supportive adults. The sight of these kids and their activism fills me with hope.

Berlin is just one of more than 2,000 locations in 125 countries where children have decided to skip school and join the climate strikes. Students are standing up for climate action in Albania, Bangladesh, Brazil, China, Egypt, India, Kenya, Mexico, the Philippines, the United States, and many other countries.

Let’s not underestimate these young activists. Student protests have helped shape history – think of youth protests in Apartheid South Africa or the Arab Spring. The children protesting today are making great use of their rights to free expression and peaceful assembly, and they are raising awareness of the existential threat posed by climate change.

But the most important question to them is: Will they be remembered as the youth movement that made world leaders finally take action on climate change?