How many trees should be planted per person to avoid climate catastrophe?

Plant a tree It has become the most popular slogan for tackling climate change. So much so that we see it in advertising and it is among the stellar metrics in corporate sustainability strategies. It seems perfectly reasonable: A mature tree can absorb about 22 kg of carbon dioxide (CO₂). annually, according to the European Environment Agency (EEA). The scientific community agrees that the protective shield for mitigating the global carbon footprint is the expansion of forest cover.

Through the process of photosynthesis, trees extract carbon dioxide from the air to aid the growth of their leaves, branches, and roots. At the same time, Forest soils can also sequester large amounts of carbon. Trees also provide vital support for millions of species of animals, plants, fungi, lichens, and bacteria. The ecosystem services they provide are also essential to rural people.

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Million million trees. This was the goal set by the United Nations in 2005. Since the launch of the global campaign known as Trillion Tree Campaigncorporations, non-profit organizations and governments are rolling up their sleeves “cultivate the planet”. This is exactly the slogan that gave rise to the global movement.

Planting trees is considered panacea It can stimulate economic development, fight climate change, contribute to wildlife habitat, even benefit health, protect water, etc,” says Meredith Martin of North Carolina State University. to the New York Times.

But plant trees It is not the ultimate solution against climate change. Trees cannot be planted anywhere. Certain factors such as the climate, soil, or local species in the area to be cultivated must be taken into account.

Is there enough space?

One of the questions that haunts the idea of ​​planting trees is If there is already space to house them. But before finding out if there is space, it is necessary to find out how many trees have been planted. in 2015, A study published in the journal nature The total number of trees at that time was estimated at 3 million trillion trees.

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a A study published in the journal Sciences in 2019 Led by Jean-Francois Bastin of the Federal Polytechnic School of Zurich (ZTH), it has given a lot of optimism regarding the world’s forested area.

Ecosystems It could support an additional 900 million hectares of continuous forest“, reassured the researchers in the investigation. This represents an increase of more than 25% of the forest area. The countries with the largest area, according to the research, were Russia, the United States, Canada, Australia, Brazil and China.

How much do you have to plant?

Charles Harvey, engineer and professor of civil and environmental engineering at the Massachusetts Institute of Technology He speaks to the MIT Climate Portal that “although planting more trees is a good idea for the world, The truth is much more complex than assuming that more trees can cancel out our emissions“.

One of the problems mentioned by the engineer is that trees are not eternal. They are a two-way highway. “When it dies and decomposes or is burned in a forest fire or is cut down and burned for fuel, The trees release all the carbon dioxide they were hiding inhe adds in remarks to MIT Climate Portal.

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Some scientists have already warned that trees will need more nutrients to grow if the level of carbon dioxide concentration in the atmosphere increases. And if they limit Their ability to store carbon is also reduced.

Spanish case

in Spanish territory There are 28 million hectares of forest area. And these green areas, as explained by Carmen Aviles, professor at the Higher Technical School of Forestry, Forestry and Landscape Engineering at the Polytechnic University of Madrid (ETSI-UPM), About 800 billion tons of carbon dioxide are sequestered each year.

And from this surface, Only 37% are wooded. “The trees that we currently have allow us to absorb emissions of about 50 million tons annually,” Aviles says. But this amount It is not enough to neutralize our emissionsMore is emitted from the Spanish economy than the forests absorb.

What if non-wooden roofs were filled with trees? It’s not that easy, explains Aviles. “It is difficult to say what maximum capacity Spain might have to growHe notes that the arable area is “determined by changes in use and by the different needs being provided”.

The key is management.

From the FSC organization, they point out that the main barrier to greening of trees where possible has to do with the use and care of forests. “Forest management is the key” they repeat.

Of the total forest area in Spain, Only 20.3% have tools for proper management. This image was created by the Director General of Biodiversity, Forests and Desertification of the Ministry of Ecological Transition and Demographic Challenge, María Jesús Rodríguez de Sancho, In an interview last January.

“If it is well managed, Forests can be used sustainablyThey explain from the Forum for Security Cooperation.