Why planting trees is not a silver bullet to climate change

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“Nature-based solutions” are gaining ground in tackling climate change while protecting biodiversity. Planting trees, a key part of several countries’ pledges at COP26, is one such proposal, but experts say reforestation, while essential, is far from a silver bullet to crises climatic.

Two of the world’s largest producers of fossil fuels, Russia and Saudi Arabia, have pledged in recent weeks to become carbon neutral by 2060. Moscow and Riyadh plan to offset much of their carbon emissions from fuels fossils by planting millions of trees.

And they are not alone. COP26 host Boris Johnson wants to make tree planting a priority at the United Nations climate conference, along with further action on “coal, cars and money”.

“To be net zero for carbon you have to be net positive for trees, and by 2030 we want to plant many more trees in the world than we are losing,” the Prime Minister said British in August.

Planting trees is part of a larger set of environmental measures known as ‘nature-based solutions’, which the UN and many scientists say are essential to avert catastrophic climate change – and that the organizers of COP26 hope to propel into the mainstream.

The International Union for the Conservation of Nature (IUCN), which coined the term, defines nature-based solutions as “actions to protect, sustainably manage and restore natural and modified ecosystems”. The protection and expansion of forests is at the heart of this approach.

“Forests, and in particular tropical forests, absorb around a third of greenhouse gases emitted each year,” explained Anne Larigauderie, executive secretary of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) , who works with the UN on protecting biodiversity, in an interview with AXADLETM. “They could do a lot more if we stopped deforestation and invested more in forest management and the protection of these ecosystems.

Mangrove restoration is often cited as a key example, as these unique ecosystems act as natural barriers against coastal erosion and flooding.

Just planting trees, however, doesn’t cut it.

“Nature-based solutions must have a double advantage,” said Freddy Rey, an ecological engineering specialist at the National Institute of Agronomic Research (INRAE). “At least one should concern nature, and the other society – for example, the fight against climate change, health, food safety or protection against natural hazards.

In France, INRAE ​​researchers have vegetated the banks of certain watercourses to fight against erosion and therefore flooding. Rey said this offers a more sustainable alternative to traditional dams.

“Over time the vegetation will expand, while the artificial barriers will wear down,” he told AXADLETM. According to IUCN, nature-based solutions are often less expensive in the long run. than the construction and maintenance of technological infrastructure.

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“Buzz” around solutions based on nature

Of course, planting trees and expanding green spaces are not new ideas. But Rey said that at least in France, the label “solutions based on nature” has succeeded in “creating a buzz” around ecological practices, especially among elected officials. Lawmakers work with INRAE ​​to develop solutions to local environmental problems. NGOs also play a role, like the France Nature Environnement group, which last year published a guide for cities seeking to implement this type of solution.

Although practices such as reforestation may be “low-tech”, they still require highly specialized research and innovation.

“Far from purely ornamental greening projects – the maintenance of which often involves intensive use of water, energy and fertilizers – nature-based solutions are based on scientific knowledge and technical know-how drawn on a large scale. part of ecological engineering, ”a recent study said.

Laigauderie de l’IPBES deplores the fact that, during major international climate negotiations, “people often talk about technical and technological solutions… and do not pay enough attention to nature as a source of solutions”.

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Despite all the promises they contain, nature-based solutions should not be seen as a quick fix for the climate. The natural world is constantly changing and evolving, and researchers must adapt accordingly. Planting along shores and streams, for example, has its limits.

“If we master the design methods of civil engineering based on mechanical and physical properties, it is not the same for plant engineering, which involves living materials whose properties are much more difficult to control”, said André Evette, researcher at INRAE ​​in a statement.

Mountainous regions, lakes and actively used waterways present special challenges.

Disguise the “climate trashing”

“We shouldn’t think we’re going to change the world with stems of plants. We’re not going to stop the tidal waves with branches, ”Rey said. “We need a balance between these solutions based on nature and civil engineering know-how.

Some NGOs, such as Friends of the Earth, fear that nature-based solutions may “disguise cases of climate degradation as usual.”

“Under the guise of nature-based solutions, large corporations and governments continue to develop… industrial agriculture and fossil fuel extraction, while claiming to fight their climate impacts by investing in activities such as planting. massive trees, ”Friends of the Earth wrote in a recent statement.

Larigauderie also noted that the concept can be slippery and cautions against putting too much stake on it.

“Nature will not be able to absorb a frantic increase in our consumption,” she warned. “The number one message is that we need to reduce our energy consumption and rethink our lifestyles and agriculture. Nature can do a lot for us, but we also need to correct ourselves. “

The COP26 summit will take stock of the actions taken by governments to achieve the objectives set by the 2015 Paris Agreement and the major challenges that remain to be met to keep global warming below 1.5 ° or even 2 ° Celsius . Building on recent COP15 discussions on biodiversity, COP26 has nature-based solutions on the agenda, with one of its 10 working days dedicated to the theme of nature.

Many hope this will only be the beginning of what the UN calls “an essential part of the overall global effort to achieve the goals of the Paris Agreement”.

This article has been adapted from the original in French.

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