Planting trees, an insufficient solution to fight against climate change

What if we used nature to fight against climate change? For the UN and climate and biodiversity experts, there is a category of solutions called “nature-based solutions”. This recent concept, little known to the general public, refers to practices that use natural resources to fight against climate change.

According to the International Union for the Conservation of Nature (IUCN), the NGO that defined this concept, they are defined by “the preservation of ecosystems”, “the improvement of the management of ecosystems”, “the restoration of degraded ecosystems or the creation of ecosystems”.

The protection and creation of forests is one of these most symbolic solutions. “Forests and, in particular, tropical forests absorb about a third of the annual share of greenhouse gases. They could do a lot more if we stopped deforestation, if we invested more in forest management and in the protection of these. ecosystems “, indicates Anne Larigauderie, secretary general of Ipbes, the organization which coordinates global scientific expertise on biodiversity, contacted by France 24. The reconstitution of mangroves is also often cited as an effective example: they play, in indeed, a role of natural barrier capable of avoiding coastal erosion and flooding.

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However, it is not enough to plant trees to meet the criteria. “These nature-based solutions are projects that must have dual benefits. At least one of them must relate to nature, and the other to society, for example, the fight against climate change, health, food safety or even the reduction of natural risks “, explains to France 24, Freddy Rey, research director in engineering ecology at the National Institute of Agronomic Research (Inrae).

In France, INRAE ​​scientists have introduced plants to certain river banks to fight against erosion, and therefore flooding. For Freddy Rey, this type of alternative to traditional dikes and riprap has the advantage of being more durable than traditional techniques. “Over time, the plant cover will grow, conversely, the gray structure will wear out,” he explains. According to the IUCN, nature-based solutions are “often less costly in the long run than investments in technology, construction and maintenance of infrastructure”.

“Craze” around these eco-friendly solutions

Of course, planting more trees or making cities green is nothing new. But for Freddy Rey, the creation of “solutions based on nature” has the merit of “arousing enthusiasm” in France around these ecological practices, in particular among elected officials. The latter work with INRAE, which offers them solutions adapted to local environmental issues. For his part, the NGO France nature environnement provides a guide, intended in particular for municipalities.

The generalization of these practices makes it possible, moreover, to reinforce the knowledge of natural environments and living things. “Far from simple ornamental or recreational greening operations (often accompanied by intensive management in terms of watering, energy, inputs), nature-based solutions are based on scientific knowledge and technical know-how largely derived from ecological engineering “, can we read a recent study on the subject.

In this context, Anne Larigauderie regrets that during major international meetings on climate change, “we often talk about technical and technological solutions” and that “we do not focus enough on nature as a source of solution. “.

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Although there are many virtues, nature-based solutions cannot be the silver bullet to all climate problems. Because the living is constantly moving and evolving. Researchers must therefore adapt. The greening of the banks, for example, has its limits.

“If the design methods of civil engineering works, based on mechanical and physical properties, are perfectly mastered, this is not the case for plant engineering which brings into play a living material, the properties of which are much more difficult. to be checked “, specifies in a statement André Evette, researcher in ecological engineering at INRAE. In mountainous regions, on lakes and inland waterways, “plant techniques still raise questions, especially as to their resistance”, it is also specified.

“We must not think that we are going to change the world with plant sprigs”

“We must not think that we are going to change the world with plant sprigs. It is not with branches that we will avoid tidal waves. We need a balance between these solutions based on nature and know-how linked to civil engineering, ”adds Freddy Rey.

Anne Larigauderie points to the risk of drifts. “It makes sense to produce biofuel in a derelict area, on vacant land or an area on the outskirts of a city. On the other hand, it doesn’t make sense if you convert natural spaces to produce biofuel. Such a logic goes against biodiversity, “she warns.

Some NGOs, like Friends of the Earth, argue that “nature-based solutions” are a pretext to continue to pollute as much as before.

Anne Larigauderie also fears that these practices are misguided. “Nature will not be able to absorb a frantic increase in our consumption. The number 1 message remains to say that we must reduce our energy consumption, review our lifestyles, our agriculture and our food. Nature can do a lot for us. but we also have to correct ourselves, ”she says.

The COP26, which begins on Sunday, must take stock of the actions taken by states to achieve the objectives of the Paris agreement. As at the COP15 on biodiversity, which took place from October 11 to 15, “nature-based solutions” will surely be talked about. Because, for the UN, it “constitutes an essential element of the overall global effort to achieve the objectives of the Paris Agreement”.