Turning plants and trees into CO2 sponges

The use of the right species in each ecosystem is one of the most practical, economical and safe natural formulas for decarbonizing the planet.

By Miguel Ángel García Vega

Maybe it all happens in adolescence and the rest is an endless blur of days. A few decades ago, boys entering the current second year of Bachillerato (European Baccalaureate course) and Bachiller diploma (baccalaureate diploma) had to choose between science and literature.

In Biology—a branch of science—some of the required knowledge was understanding the process of photosynthesis. Basically, it explained the role of plants in the process of carbon dioxide fixation (C02). While the teacher would deliberately warn the class: "It's an important topic, and it might show up on the college entrance exam (now EBAU).” Nerves were running high.

Instead of "entrar (be on, show up on)” they used the word "caer (the teacher will slip it in)." Semantics counted. In those days, no one thought that plants and trees were essential to mitigating climate change. "They are very efficient CO2 capturing machines," summarizes Jaume Martínez, a member of the Institute of Molecular and Cell Biology of Plants (IBMCP). "One plant, or several, on a balcony absorbs quite a lot of dioxide, but not all of the 8 billion human beings living on the planet have, or can have, one," he admits. However, they are, perhaps, part of the root of the solution. They fix soils, prevent soil erosion, provide nutrients and generate microbiodiversity. "We have to take care of that land," warns the scientist. And this brings the conversation to two different places. Forests are food producers. Under a certain level of control. It's a mistake to establish roots—as was done in Galicia, back in the ‘90s, with eucalyptus, which fixes the soil, but which, on the other hand, consumes enormous amounts of water and kills native species—with plants that aren’t naturally part of the historical ecosystem because they become invasive, a threat. 

Those young high school students learned the value of balance in Biology classes. The other end of the discussion extends all the way to the fields. Forests have had to make room for humans to plant food within an increasingly difficult-to-satisfy population. But in the face of certain uncompromising positions, agriculture in itself is not the solution to all problems. The key is to plant those species that are suitable to the terrain and the climate and that are capable of capturing CO2. "A crop that fixes the dioxide —insists Jaume Martínez—“and does not allow erosion.” Let’s go back to the start. "Forests are CO2 sinks and the countryside must move towards more sustainable plantations.” They also act as sponges, accumulating water. But it's not only useful just to plant them. Their behavior must be monitored. The strategy isn’t to plant and forget but to plant and care for.

In a world where it seems that much knowledge is taken for granted, there are some basic elements that people may overlook. Photosynthesis is only carried out by the green parts of plants (leaves). "That's why flowers aren’t capable of capturing C02," says Jesús Miguel Santamaría Ulecia, PhD in Biology and the Environment and professor of Analytical Chemistry at the University of Navarra. "However," as we've seen, "those that truly act as sponges to capture atmospheric carbon are trees, which can fix large amounts of carbon in their woody parts.”

It seems that the solution is there: crouching on the ground, taking a clod in your hand and letting it slip through your fingers. To feel its importance. Because photosynthesis extends from the land to the sea, to the water. Phytoplankton (feeding with photosynthetic processes) that roam in search of light and food in the seas or marine angiosperms (plants adapted to live in the sea) are responsible for photosynthesis. But we must protect that green world. "They suffer from pollution and rising temperatures: their carbon sequestration capacity is altered," warns Sergi Munné-Bosch, professor in the Department of Evolutionary Biology, Ecology and Environmental Sciences at the University of Barcelona. He launched a proposal that is gaining more and more support: the creation of sanctuaries. "Spaces that aren’t accessible to man. In this way, they would be fully protected." But why not? Many natural parks already have a limited number of visitors and some areas aren't even accessible. This occurs, for example, on Native American land. There is a proposal to protect its fragility. Nothing new. We've lived with these reservoirs for decades. Perhaps without realizing it. Everything can be essential in this ecological equation. Remember the much-publicized 15-minute city proposed by the famous French-Colombian urban planner Carlos Morales in Paris?  "Perhaps it doesn't have a wide-ranging effect, but it does have a profound component of raising people’s awareness, of the neighborhood they live in, of those who walk through it and enjoy a garden and its plants and trees," Munné-Bosch describes. What cannot be done is to create flowerbeds or parks with species that don’t belong to that landscape, as is often done in some cities. Over time, it's a harmful proposition.

Throughout this story, which began in a Biology class, what space is left for technology? "In green hydrogen's case, it's very positive," admits the Catalan expert. The problem is time. We don’t have 20 years to solve the energy crisis, but three. But man—it’s in our DNA—has been able to find the most complicated answers. Remember the quote from former U.S. President John F. Kennedy on September 12, 1962, three months before his assassination, at Rice University in front of hundreds of students: "We choose to go to the moon in this decade and do the other things not because they are easy, but because they are hard." This is what defines human beings, who have been on this planet of water and land for more than 400,000 generations. Anyway, the forests are there, the plants are there to help when they're most needed. This much was taught, once upon a time, in a Biology class

Miguel Ángel García Vega
He has been writing for EL PAÍS for some 25 years, currently for Cultura, Negocios, El País Semanal, Retina, Suplementos Especiales, and Ideas. His texts have been republished by La Nación (Argentina), La Tercera (Chile) or Le Monde (France). He has received, among others, the AECOC, Accenture, Antonio Moreno Espejo (CNMV) and Ciudad de Badajoz awards.