The Plant-for-the-Planet is a children and youth initiative that was launched in January 2007. At the end of his school presentation about the climate crisis, nine-year-old Felix Finkbeiner announced his vision to his classmates: “Let’s plant one million trees in every country on earth!” The current goal of the children and youth initiative is to plant a trillion trees worldwide. Trees are the cheapest and most effective means of binding CO2, allowing us more time to reduce greenhouse gas emissions to zero and mitigate the climate crisis. In 2011, the United Nations Environment Programme (UNEP) handed over the long-established Billion Tree Campaign, along with the official world tree counter, to Plant-for-the-Planet. As the children’s aim is now to plant a trillion trees, they transformed the Billion Tree Campaign into the Trillion Tree Campaign and developed an interactive online tool that motivates others to get involved in planting (trilliontreecampaign.org). So far, with the help of many adults, Plant-for-the-Planet youths have already planted more than 13 billion trees. These children teach and empower others to become Climate Justice Ambassadors. More than 91,666 children from 75 countries are already participating. On the Yucatán Peninsula in Mexico, Plant-for-the-Planet plants on average a new tree every 15 seconds. This project demonstrates just how easy it is to make planting trees so effective on a large scale.