Some are sparkly glitter heels. Some have plants growing out of them. Others have messages for future generations. Thousands of shoes stood in silent protest in Paris yesterday. Their owners are the climate change activists who have flocked to the French capital for the massive U.N. climate change summit that started today.

Around 200,000 were expected at the mass marches yesterday but because of tight security post Paris-attacks they were banned from doing so. “The shoes are marching for us,” one Parisian man, René Stroh, told CNN. The messages in the shoes called for the world to avoid the most devastating impacts of climate change by abandoning fossil fuels and stopping the farming of so much livestock.

The display of shoes at the Place de la République saw a human chain of activists that stretched down Boulevard Voltaire and up to the Bataclan, the music venue where so many were shot and killed earlier this month. While banned in Paris, mass protests demanding climate action did continue all around the world from United Kingdom and Australia to Mexico and China. It may have been disappointing for many that the action didn’t go ahead but this was a touching show of silent protest in its place.