DDB China Group took over a busy pedestrian crossing and placed a large canvas featuring a leafless tree on the road. On either side of the crossing were sponge cushions soaked in green environmentally-friendly washable and quick dry paint.
As pedestrians walked towards the crossing they stepped on the sponges and the soles of their feet made footprints on the tree. Each green footprint added to the canvas like leaves growing on a bare tree. By walking they could create a greener environment.
Nice way of re-language carbon footprint to green footprint ;-)