CNN's global series i-List takes you to a different country each month. In February, we visit Germany and look at changes shaping the country's economy, culture and social fabric.
New York (CNN) -- It's not every day that a 13-year-old boy gets a chance to address the United Nations General Assembly. But Felix Finkbeiner is no ordinary teenager.
Finkbeiner is already the head of his own organization, Plant for the Planet, dedicated to planting millions of trees all around the world.
At the U.N. earlier this month, Finkbeiner had one item on his agenda: taking adults to task for their lack of action on planting trees.
In the normally staid U.N., Finkbeiner had a field day telling off a group of adults. His message to the diplomats was simple: "stop talking and start planting."
Finkbeiner warned the countries that disappearing trees would create a climate crisis for children's future.
"We children understand that the adults know everything about these crises, but we children don't understand why there's so little action," he said.
Plant for the Planet was founded in, of all places, a fourth grade classroom in his native Germany.
A presentation Finkbeiner gave in class about Nobel Peace Prize winner Wangari Maathai, who planted 30 million trees in Kenya, inspired the movement.
But Finkbeiner believes this tree crusade can only be successful if it is led by children.
"We children are the majority in the world but we can only make a difference if we work together. So we have to work together because if we do this, we can have a big impact," he says.
This tree-planting campaign has already had an impact worldwide. Finkbeiner says there are 100,000 children participating in 91 countries with 3.5 million trees planted.
Maathai, who also addressed the U.N. on the same occasion, was impressed with Finkbeiner's success.
"It is an indication of the kind of inspiration and hope we should all have because when they start this young with the conviction and the commitment, then you know definitely there's hope."
After her speech, Maathai and Finkbeiner shared some tree talk and a hug in the hall.
Later on further uptown, Finkbeiner addressed an entire audience of teens at a New York City middle school. His speech was a battle cry to his peers. "It's not about saving the polar bear. It's about saving our future."
Finkbeiner offered the students, who rarely see trees in the concrete jungle of Manhattan, some suggestions on planting trees.
He encouraged the students to organize tree-planting parties in their community. Twitter and Facebook could be used to spread the word on tree events, Finkbeiner told the curious group of youngsters.
For those seeking even more sophisticated means of getting news out, Finkbeiner offered tips on writing press releases.
Jonathan Mejia, a student who attended the presentation, left feeling inspired to "go out with a couple of my friends to a park and plant a lot of trees in a common area that everyone goes, like maybe Central Park."
This is exactly the kind of momentum Finkbeiner hopes to inspire in children around the world.
"We cannot trust that the adults alone will save our future," the young tree ambassadors says. "We have to take our future in our own hands."