As income levels in China increase, more people are driving cars, and China Environmental Protection Foundation hired DDB China to come up with a way to hammer into people’s heads that walking can be a better choice than driving. The result was beautiful — a public art campaign that had pedestrians “painting” leaves onto a tree with their feet as they crossed the street.

The company set up an “outdoor advertisement on the street” — a 41-foot-by-21-foot painting of a tree spread out across a pedestrian crossing. It was flanked on either side by sponge pads filled with washable, quick-dry paint. As people walked through the paint and onto the tree — sometimes on purpose, sometimes without realizing what was happening — their footprints created a green canopy on the once-bare branches.

Reader support helps sustain our work. Donate today to keep our climate news free. All donations DOUBLED!

Grist thanks its sponsors. Become one.

These trees ended up being installed in 132 roads in 15 cities in China, where almost 4 million pedestrians participated. The idea was to make people feel the connection between walking and the environment more directly — it’s one thing to tell everyone that avoiding cars is good for trees, but a whole other thing to watch a forest blossom under your feet.