Is tree planting overrated? You need to know where and how

On September 7, we celebrate the International Day of Clean Air for Blue Skies. Isn’t it a wonderful occasion to plant a tree and equip the world with another carbon dioxide absorber? Paradoxically, the latest scientific research suggests that the trend of reforestation does not bring as significant results as is commonly believed. However, it is not too late to change that.

A noble idea, difficult implementation

The world is sinking into a climate crisis, caused by rising concentrations of greenhouse gases in the atmosphere. To prevent disaster, tree planting is being promoted in areas that were once forested. Oaks, beeches, and maples are expected to absorb CO2, store it in their trunks, roots, and leaves, and thus counteract further climate change.

The effectiveness of this theory was examined by scientists from China, France, the United Kingdom, and the United States, who analyzed in detail the climate potential of reforestation. To do so, they measured the land area that was once covered with trees and subtracted urbanized areas, farmland, and nature reserves. They also excluded regions where tree planting could have the opposite effect – areas frequently covered with snow (a white surface stores less heat than the dark color of a forest) and areas where trees’ water demand would reduce river and stream flows by more than 5%.

What did they find? The maximum area of the Earth worth reforesting is 389 million hectares – twice less than originally assumed.

Obstacles for ecologists

Limited space for reforestation is not the only obstacle to saving the climate through tree planting. The study’s authors also analyzed the declarations of individual countries and concluded that where the potential is greatest… the least planting is done.

If we sum up all global commitments to reforestation, we get a total of 230 million hectares – only 59% of the previously calculated potential. Worse still, 90% of these commitments come from low- and middle-income countries – the intentions are admirable, but the resources for implementation are lacking. African countries alone have pledged to reforest more than 100 million hectares, but conditions for planting trees on this continent are often far from optimal.

On the other hand, in Europe we have reason to be ashamed. We want to plant trees on only 13% of the areas identified by scientists as worth reforesting. The situation looks similar in South America.

Tree planting helps, but it will not save the world

The authors of the study emphasize that tree planting looks attractive on paper, but it does not always translate into real relief for the Earth. One example is the ambitious Australian 20 Million Trees Program, which assumes that by 2030 a new forest will be created storing 0.2 million tons of CO2. That is only 0.04% of the country’s emissions!

Unfortunately, tree planting has also become one of the most popular greenwashing tactics. Companies that invest in a thousand seedlings and a dozen shovels feel absolved of years of neglect in reducing emissions, saving energy, or active recycling. The balance sheet of gains and losses, however, remains negative.

So should we give up on reforestation? Researchers argue that we should not, but we must know where and what to plant. Not all species promote biodiversity in a given area, and the wrong location of a forest can do more harm than good. Similar conclusions were published a few months earlier by scientists from the University of California, Riverside. Climatologist Bob Allen speaks openly: Reforestation is not a silver bullet. It is an effective strategy, but it has to go hand in hand with serious emissions reductions.

Driving 50 km by car to plant two trees as part of a trendy social campaign may boost our mood and look good on social media, but from a climate perspective, it may not be the best shot.

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Bibliography:

Yijie Wang et al., Land availability and policy commitments limit global climate mitigation from forestation.Science 389,931-934(2025).DOI:10.1126/science.adj6841

Allen, R.J., Lee, YC., Thomas, A. et al. Atmospheric chemistry enhances the climate mitigation potential of tree restoration. Commun Earth Environ 6, 367 (2025). https://doi.org/10.1038/s43247-025-02343-9