On the eve of the Paris climate conference, the Eiffel Tower went green.

Through December 3, an art installation called “1 Heart 1 Tree” will project virtual trees on the Eiffel Tower. The installation is part symbolism, part practical, like much of the climate conference itself. In addition to projecting an image of hope and unity as it flashes “100% Renewable” across the Eiffel Tower, the organization is using the funds it raises to promote reforestation efforts—a necessity if we want forests to capture some of that carbon we’re still emitting into the atmosphere—in partner with countries like Brazil, Peru, Senegal, Kenya, France, India, and Australia.