Under a fine but persistent rain, a multicolor patchwork of rain jackets and umbrellas are gathered enthusiastically, awaiting a speaker. Pushing past cables and amps spread left and right, Felix Finkbeiner makes his way to the front of the crowd, quickly grabbing the mic handed to him.

That day in Munich, 10,000 people braved the humid gray day to lift their signs on the Bavarian city streets. A figure of the movement, with his white t-shirt printed in the colors of his organization Plant-for-the-Planet, he wouldn’t have missed this event for anything. From Tokyo to Cape Town, 1.4 million students felt the same.

As he addressed the audience, his glasses fogging, a young woman stood behind him, waving a green sign at arm’s length that summed up Plant-for-the-Planet’s mission. “Plant a tree,” it said to the cameras. Finkbeiner knows it’s hard to give these kinds of speeches, but it’s become easier as the years go on. “It’s never easy to get a message across, especially in circumstances like these,” he says a few days later, getting off a train that has taken him across Germany.

Founded by Finkbeiner when he was just nine years old, Plant-for-the-Planet brings young people around the world together to convince their generation – and the ones preceding it – to act and fight for the planet’s future. Plant-for-the-Planet aims to slow climate heating by reforesting the earth. “And while very few saw it coming, the magnitude of the 15 March demonstration is a sign of hope for all of us,” the young man says.

A trillion trees

Felix Finkbeiner, founder of the organization Plant-for-the-Planet.
Credits: Plant-for-the-Planet

The mobilizing force of Felix is impressive. Having started with just a handful of classmates, Plant-for-the-Planet now has an army of more than 63,000 “climate justice ambassadors” across 58 countries, mostly aged nine to 12. Under the direction of the United Nations Environment Program (UNEP), Plant-for-the-Planet has planted a billion trees since its inception in 2007, far surpassing the aspirations of its founder, who will be 22 in October.

The slowing of deforestation and the planting of trees is one of the proposed solutions for rising CO2 emissions and for climate heating. “The earth’s forests generously mop up about a quarter of the world’s fossil-fuel carbon emissions every year,” wrote Nadine Unger, assistant professor of atmospheric chemistry at Yale University, in a New York Times editorial, which is, however, critical of combatting climate change by planting trees.

Recently, Plant-for-the-Planet’s goals have been updated, aiming to reach a trillion trees in 20 to 30 years, following a new study led by Thomas Crowther, a British scientist specializing in ecosystem ecology, and his team. By encouraging a massive restoration of earth’s forests, researchers tried to estimate the amount of carbon that could be captured by planting these trees.

With 3 trillion trees, that’s about 400 gigatons right now, and if you increase that capacity by a trillion trees, that’s the equivalent of hundreds of gigatons captured in the atmosphere, or at least 10 years of human-caused emissions completely wiped out,” Crowther said to The Independent, stating that trees are “our most powerful weapon in the fight against climate change.” Although Crowther’s study is not yet published, it has already inspired considerable measures in some governments to respond to the climate emergency.

The researcher Thomas Crowther, founder of the Crowther Lab.
Credits: esri

On 16 February 2019, visiting a nursery in Tasmania, Australian Prime Minister Scott Morrison announced that the country would plant one billion trees by 2050 to reach Paris climate accord goals. For an estimated cost of 8 million euros, the idea is to “help eliminate 18 million tons of greenhouse gasses from the atmosphere per year,” from a country that produces on average 500 million tons of equivalent CO2 each year.

Australia follows announcements from Pakistan, India and even China. Since 2015, for a sum total of 169 million euros, Pakistan reached its goal of one billion replanted trees to combat soil erosion and deforestation. In the Khyber Pakhtunkhwa province, 16,000 people have worked for almost four years on reforesting this part of the country by planting 42 different tree species.

A February 2019 study by NASA made a surprising and counter-intuitive revelation: our planet is greener than it was 20 years ago. Analyzing two decades of satellite data, it pinpointed China and India as the most significant players in this phenomenon. The study determined that the effect is primarily the result of reforestation and agriculture programs being led in the two countries.

India has set out to break world records, with 66 million trees planted in 12 hours in July 2017, while China has become a model in its own right with its “green wall.” Since 1978, it has also planted more than 66 billion trees in the Gobi Desert to combat desertification. Still, researchers point out that the positive events noted in India and China are far from compensating losses in vegetation in countries like Brazil and Indonesia.

Credits: Plant-for-the-Planet

Stop talking, start planting!”

Felix Finkbeiner has spent a lot of his life thinking about reforestation. The son of a businessman and a textile engineer, the schoolchild in the Bavarian town of Uffing am Staffelsee worried about the fate of the polar bear. For a weekend homework assignment, his instructor asked the class to research global warming. What Finkbeiner learned about his favorite animal dismayed him.

A few clicks later, his research led him to the extraordinary story of Wangari Maathai. Founder of the NGO Green Belt Movement, the Kenyan biologist led a 30-year campaign to plant 30 million trees. Her work earned her the Nobel Prize in 2004, a fact that moved Finkbeiner.

Deceased on September 25, 2011, Wangari Maathai is the first African woman to receive a Nobel Peace Prize.
Credits: The Green Belt Movement

In front of his classmates, he explained how trees capture carbon dioxide via photosynthesis and emit oxygen, also absorbing greenhouse gasses from human activities. In conclusion of his presentation, the boy called on everyone to follow the example of Maathai and to plant “a million trees in every country in the world!”

On 28 March 2007, Finkbeiner planted his first tree at the age of nine, in front of the entrance to his school. The small wild apple was hardly impressive, but it held symbolic significance. The act started an unprecedented craze, and it quickly became an example for other schools. In a single year, the students planted 50,000 trees. The small group of students organized, officialized, set up a planting competition, and relentlessly encouraged other young people to imitate them in their own communities. These environmental events and their remarkable challenge caught the eye of the media and world policy makers.

Suddenly, Finkbeiner was being called over and over to speak in front of adults, like this 2011 speech at the United Nations General Assembly to inaugurate the International Year of Forests – which aimed to promote good forest management and conservation. Dressed in a gray hoodie with his initiative’s logo on it, the 13-year-old teenager took to the pulpit, surrounded by friends and members of Plant-for-the-Planet. With poise, he questioned his audience on their inaction. His message was clear from the first word: “Stop talking, start planting!”

Speech of Felix Finkbeiner to the United Nations General Assembly in 2011.
Credits: Plant-for-the-Planet

After high school, he lived in London for three years. In 2018, still working with Plant-for-the-Planet, he earned a degree in international relations. The organization has inspired much of Thomas Crowther’s research. Crowther is responsible for the first worldwide tree census. His study, published in 2015 in the science journal Nature, includes two years of work and reveals that the earth contains around 3 trillion trees, seven times more than what was previously believed.

The study added that around 10 billion trees are lost each year and that planting a billion trees is a worthy effort, but insufficient to really effect change. “I thought (the Plant-for-the-Planet activists) might be disheartened,” Crowther said to National Geographic. “Instead, they said: ‘OK, now we have to scale up.’” But some researchers quickly warned the scientific and nonprofit communities about this massive planting concept.

For the campaign “Stop talking, start planting”, the organization has surrounded itself with personalities, like here Harrison Ford.
Credits: Plant-for-the-Planet

Conscious and targeted planting

In a 2006 study, researchers from Lawrence Livermore’s national laboratory in California expressed doubt as to the validity of this reforestation. In Phys.org, they stated that planting new forests in the tropics causes a cooling effect, while reforesting in colder regions actually causes more heating. “In fact, planting more trees in high latitudes could be counter-productive from a climate point of view,” says Govindasamy Bala, who led the study.

You have to realize that trees can influence the climate in three ways,” Finkbeiner says. “They first have a role in determining CO2 storage, and in evapotranspiration.” Evapotranspiration is the result of both water evaporating into the atmosphere and plant transpiration. “Then there’s what’s called the albedo effect,” which measures a surface’s reflective power. The clearer something is, the stronger its albedo is. Conversely, the darker it is, the weaker its albedo is, and the more it absorbs the sun’s rays. We should also point out that evapotranspiration itself increases the albedo effect, and all that contributes to keep the earth cool.

In tropical areas (or areas of low latitude), trees grow so quickly that they absorb little solar energy. The albedo is therefore stronger. In higher altitude regions, trees stock less CO2, growing more slowly. The albedo there is weaker, and large-scale planting in these zones could have a negative impact on the climate. “That’s why we always plant trees in tropical or temperate zones,” Finkbeiner says, “because they’ll affect the cooling of the planet more there.”

Credits: Plant-for-the-Planet

In addition, the choice of tree species is essential. Certain plants are more apt than others to absorb CO2, Science Focus explains. In photosynthesis, a plant uses CO2 to produce glucose, and it needs six molecules of CO2 to produce one glucose molecule. Those will then be used to create energy. A fast-growing plant is a plant that quickly absorbs carbon dioxide. The problem is that kind of plant doesn’t live very long and, when it dies, all that stored CO2 gets released again. That’s why leafy trees are more often planted. The key will be to do conscious and targeted planting, and that’s the focus of studies Finkbeiner is leading now.

Since September 2018, the young man has been working towards a doctorate in environmental sciences at Crowther Lab – founded by Thomas Crowther – in Zurich. Together with Crowther and a group of interdisciplinary researchers, he’s studying “the most efficient approaches to forest restoration,” based on the principle that knowledge gained from functioning terrestrial systems will allow us to understand and come to terms with global climate heating. “It’s very important to specify that planting trees alone is not a solution to climate change,” Finkbeiner says. It’s an important part of the solution, but reducing our CO2 emissions, for example, also has to be a priority.”