Earlier this month, world leaders like President Barack Obama, United Nations Secretary-General Ban Ki-moon and Chinese President Xi Jinping gathered in Paris for the United Nations Climate Conference (COP21).

Citizens of the world debated the issue of climate change and the possible outcomes of the conference, which were announced over the weekend. Although tensions were high, many people all over the globe put aside their differences and took part in an interactive art project that kicked off the conference — where else but on the Eiffel Tower.

Photos: 3D Projection on the Eiffel Tower

From November 30 through December 3, the Eiffel Tower became the backdrop for a 3D projection project designed to raise awareness about global reforestation. The project, called 1 Heart 1 Tree, was created by Belgium-Tunisian artist and architect, Naziha Mestaoui, co-founder of video-mapping company ES Studio.

Mestaoui created a Kickstarter campaign and, with support from “ambassadors” like Academy Award-winning actress Marion Cotillard and French correspondent Nicolas Hulot, designed an exhibit that uses the heartbeats of people around the world to create a virtual forest on the Eiffel Tower.

Pulse of the Planet

For a completely innovative addition to other projection mapped shows across famous sites all over the world, the 1 Heart 1 Tree project did something new, syncing a smart phone application (available on both iPhone and Android) to the projection. The app then generated a virtual tree for each person using it, so each person had a unique ‘tree’ appear in the light show.

How does it work? Say you download the app. You then put your finger on the phone’s camera, which works as a heartbeat sensor to capture and record your individual heartbeat. The app “uses an algorithm to analyze the chromatic microchanges from blood circulation from your finger,” according to Forbes, and uses this information to grow your virtual tree.

Because every heartbeat is different, every virtual 3D tree appeared different when projected on the Eiffel Tower.

The Virtual Gets Real

1 Heart 1 Tree’s purpose goes beyond entertainment and awareness. For every tree that users virtually created by using the app, a real tree will be planted as part of seven global reforestation projects across Australia, Brazil, France, India, the Ivory Coast, Peru and Senegal.

When users downloaded the app to partake in the project, they contributed a minimum of 10 euros each that will now go toward planting their tree. What’s more, users will be able to monitor the growth of their tree on the 1 Heart 1 Tree app.

Go inside the photos here.