It all began with a presentation in English on climate change that Felix had to give at his school near Munich in January, 2007.
During his research, Felix came across a website with information on Wangari Maathai, a Kenyan activist who, together with other women in her country, had planted more than 30 million trees to fight deforestation and soil erosion.
Inspired by Maathai, who was awarded the Nobel Peace Prize in 2004, Felix highlighted tree-planting in his presentation as a way to tackle climate change.
"At the end of the presentation I said 'let's plant a million trees in every country of the world," the 12-year-old told Deutsche Welle.
'We feel cheated'
Felix's class teacher was impressed and helped spread the word. Soon, Felix was sent to other schools in the area to talk about his ambition. Two months later, Felix's school – the Munich International School in Starnberg in southern Germany – organized the first official tree-planting drive.
The local media took an interest, other schools in the area began similar tree-planting events and Felix's idea snowballed into a local green movement. Three years later, the initiative achieved its one- millionth-tree in Germany and the group "Plant for the Planet" was born, making Felix Finkbeiner Germany's youngest founder of an environmental organization.
Today, the group is financed through donations and operates projects in 70 countries around the world.
Felix insists that the initiative isn't just about planting trees. It's also about children exchanging ideas and experiences of climate change.
"We children feel really cheated because such a lot was done for Copenhagen and at the end, what was really achieved there?" Felix said.
Wise green words
With his silver-rimmed spectacles and boyish face, Felix certainly looks his age, but he sounds somewhat older. He says that as an adult he and his generation will have to live radically different lifestyles from those of his parents' generation, if global warming is to be curtailed.
"We children want the same chances for our future as today's adults have. But I'm convinced that we can't continue the same way as we have so far. We will never achieve our goals if we continue to drive cars and fly in airplanes as we do today. Our grandparents, my grandparents, didn't do air travel either and they were happy."
Travelling the world for a cause
Felix said that he actually liked giving presentations and travelling - two things that he's been doing a lot of in recent years, even in an airplane if necessary.
He's been invited to conferences in New York, South Korea, Norway, Sweden, Switzerland, Austria and Italy to introduce his organization and talk about his plans to protect the climate.
Earlier this year, he was invited to Beijing by the Chinese government.
All that globe-trotting means that the young climate campaigner has to miss school quite often - sometimes for entire weeks. But he says his grades are pretty good and he's confident that he'll keep up with his class mates.
At home, Felix is like any other boy his age. He says he loves riding a mountain bike and playing on a computer.
Inspired by his parents
The media has traced Felix's unusual commitment and vision to protect the climate to his parents, both environmental campaigners.
His father, Frithjof Finkbeiner, founded an environmental group almost a decade ago. It's based in the family's home in a small picturesque village near the Starnberger Lake where Felix lives with his two sisters and parents. Felix grew up listening to impassioned discussions about the environment and social justice.
"I'm convinced that what my parents do has certainly influenced me. But at the same time, there are thousands of children around the world who also plant trees, who are active and give speeches and presentations like myself. I think most of them give better speeches than I do," he said.
Author: Sandra Petersmann (sp)
Editor: Nathan Witkop