Afforestation
The most intuitive climate solution, and the most frequently botched. Counting seedlings is not the same as growing a forest.
The effect arrives across lifetimes. This is a gift to people you will not meet.
Project Drawdown classifies this as Delayed.
Origins
Tree planting has a long and slightly uncomfortable history as a symbolic act.
The Chinese Communist Party launched mass afforestation campaigns from the 1950s; the Great Green Wall across the southern Sahara was proposed in the 1970s; a hundred national tree days have been declared since. Some of it worked. A great deal of it did not, and the failures share a family resemblance: fast-growing exotic species planted in rows, on land that was often not forest to begin with, counted on the day of planting and never counted again.
The most instructive failure is Scotland’s. In the 1980s, a tax loophole made planting conifers on peat bog extraordinarily profitable for wealthy investors, and vast areas of the Flow Country — the largest blanket bog on Earth, a carbon store of global significance — were drained and planted with Sitka spruce. It was afforestation. It was celebrated. And it was a catastrophe, because draining the peat released more carbon than the trees could ever absorb. The planting was the emission.
The lesson has been learned slowly and is still being learned. In 2019 a widely reported study suggested that global tree restoration could store an enormous quantity of carbon, and it produced an eruption of tree-planting pledges. It also produced a wave of scientific criticism, much of it centred on the same point: a great deal of the land identified as available was native grassland, an ecosystem that stores its carbon underground and would be destroyed by planting it.
Afforestation is the solution that most needs saving from its own enthusiasts.
What it actually is
The intuition is sound. Trees pull carbon from the air as they grow. There is a great deal of degraded land that could hold them. Growing forest on it is genuinely useful.
The execution is where it falls apart, and it falls apart in a small number of very predictable ways.
Exotic monocultures. Fast-growing eucalyptus or pine, planted in rows for the carbon accounting. They grow fast, they support almost nothing, they are prone to fire and disease, and if they are harvested on a short rotation the carbon returns to the air anyway.
Planting the wrong ecosystem. Native grassland, savanna and peat bog are not degraded forest. They are functioning ecosystems that hold their carbon in soil and support species that require open ground. Planting trees on them destroys the ecosystem and, on peat, releases more carbon than the trees will ever capture.
Planting and leaving. Seedlings need protection from browsing, competition and drought for several years. A great many planting programmes measure success on the day the photographs are taken. Survival rates measured at year five are frequently dismal and frequently unpublished.
Ignoring who owns the land. A forest that nobody local has any reason to protect will be cut for fuel or cleared for crops, and reasonably so.
Done well it looks entirely different: native species matched to the site, natural regeneration wherever a seed source survives, and clear answers to the questions of who owns it and who benefits.
The numbers
The measurement problem, stated plainly. Trees planted is the metric almost everyone reports. Trees alive at year five is the metric that matters. Reviews of large tree-planting programmes have repeatedly found survival rates far below what was claimed, in some documented cases well under half.
The land question. The 2019 global tree restoration estimate that triggered a wave of pledges was substantially criticised on the grounds that much of the land it identified was native grassland and savanna, ecosystems that store carbon underground and are damaged by afforestation. The scientific dispute has not been resolved by planting more trees; it has been resolved by being more careful about where.
Where it genuinely works: degraded land. Drawdown’s current framing is instructive — the solution is not “plant trees,” it is tree plantations on degraded land. The qualifier is doing all the work.
Natural regeneration is cheaper and better. Where a seed source survives, allowing a forest to return costs a fraction of planting and produces a more diverse, more resilient forest. The single largest reforestation event in modern history — the return of the New England forest — involved planting essentially nothing.
It is slow, and honestly so. Drawdown classifies restoration and plantation solutions as delayed. Carbon accumulates over decades. Anyone promising rapid drawdown from planting is selling something.
Why it matters
We want to defend tree planting, because the impulse behind it is the best one we have.
A person who plants a tree is doing something almost defiantly hopeful. They are betting on a future they will not see, on soil they may not own, for a benefit that will accrue to someone else entirely. Nearly every culture on Earth has independently arrived at the tree as the symbol of continuity between generations, and they were not being sentimental. They were being accurate.
Which is exactly why it deserves better than it has been getting.
The tree-planting pledge has become the climate equivalent of a thoughts-and-prayers announcement: cheap, photogenic, satisfying, and frequently disconnected from any measurable outcome. Corporations plant a million trees and do not report how many lived. Governments announce billions and plant them on grassland. The gesture has been hollowed out, and the hollowing is done by people who mean well.
The remedy is not cynicism. It is seriousness. Plant the right species, in the right place, and count them again in five years. Then it is not a gesture. It is a forest, and your grandchildren will walk in it, and they will not know your name, and that was always the deal.
What it actually takes
Answer the question “was this forest?” before anything else. If the land was grassland, savanna, or peat bog, stop. You are about to destroy an ecosystem in order to look like you are saving one. This single question would prevent most of the harm done in the name of afforestation.
Prefer regeneration to planting. If a seed source survives nearby, fence it, manage the grazing, and wait. It is cheaper, and the forest that arrives is better than the one you would have designed.
Budget for years three through ten. The planting is the cheap part and the photogenic part. Protection from browsing, competition and drought is the part that determines whether anything is alive in a decade, and it is the part that gets cut.
Native species, mixed. A monoculture is a crop. It will burn, or it will get a disease, and it will support very little in the meantime.
Make it somebody’s. A forest with no local owner and no local benefit is a forest with a countdown on it. Community forestry works because the incentive to protect the trees lives in the same place as the trees.
Where it matters most
Degraded and abandoned farmland is the honest answer, and it is everywhere: former agricultural land in Appalachia, the Atlantic Forest of Brazil, the Loess Plateau of China. This is where trees belong and where they do the most good.
The Atlantic Forest is the most ambitious restoration effort on Earth, stitching a shattered biome back together with corridors between fragments — and it works because it is replanting forest where forest was.
The Sahel is where the best lesson comes from, and it is not about planting. Farmer-managed natural regeneration — simply protecting the trees that resprout from existing root systems in farmers’ fields — has quietly greened millions of hectares at a fraction of the cost of any planting programme. The trees were already there. Somebody just stopped cutting them.
Where it must not happen: the Great Plains, the Canadian Prairies, the African savannas, and any peatland anywhere. These are not empty land awaiting trees. They are ecosystems, and planting them is destruction with a green ribbon on it.
How to tell it’s being done well
Was it forest before? The first question, and it disqualifies most bad projects immediately.
What is the survival rate at year five? Not seedlings planted. Trees alive. If they cannot tell you, they did not measure, and if they did not measure it is usually because they did not want to know.
Native, mixed species? A single fast-growing exotic in rows is a timber crop. It may be a perfectly good timber crop. It is not a forest and should not be counted as one.
Could they have just let it regrow? If a seed source survived and they planted anyway, ask why. Sometimes there is a good answer. Often the answer is that planting is fundable and waiting is not.
Who owns it in thirty years? If nobody local benefits, nobody local will defend it.
What you can do
Anyone
- Before you donate to a tree-planting scheme, ask two questions: was this land forest before, and what is your five-year survival rate? A good organization will have both answers ready.
- Plant native. A single native oak supports vastly more life than a row of exotic conifers.
- Be suspicious of very large round numbers. A billion trees is a press release. A million surviving trees is a forest.
Landowners
- If you have abandoned pasture and a woodland nearby, you may not need to plant anything. Fence out the deer and wait.
- Native mixed species, planted at the right density, will outperform a monoculture on every measure except short-term timber yield.
Policymakers
- Fund years three through ten, not the planting day. Survival is where the carbon is and it is where the money is not.
- Prohibit afforestation of native grassland and peat. This is the single highest-value line of regulation in the entire field.
- Support farmer-managed natural regeneration. In the Sahel it has greened millions of hectares for a fraction of what planting would have cost.
Business and investors
- If you buy tree-planting offsets, require year-five survival audits. Without them you have bought a photograph.
- Fund natural regeneration where it is possible. It is cheaper, better, and unfashionable precisely because it is not photogenic.
Where this matters most
Who is working on this
We are researching which organizations in our directory of 8,493 actively work on this solution, and we only list an organization once we have verified it. That research is ongoing. In the meantime, search the directory yourself:
Questions
Why do so many tree-planting projects fail?
Because they measure the wrong thing. Counting seedlings planted rewards volume rather than survival. The common failure modes are exotic monocultures, planting on land that was never forest, and no maintenance after the photographs. Survival at year five is frequently poor and frequently unpublished.
Can planting trees actually cause harm?
Yes. Planting trees on native grassland or savanna destroys an ecosystem that stores its carbon underground and supports species that need open ground. Planting on drained peat, as happened in the Scottish Flow Country in the 1980s, can release far more carbon than the trees ever absorb. In those cases the planting is the emission.
Is natural regeneration better than planting?
Usually, where a seed source survives. It costs a fraction as much and produces a more diverse and resilient forest. Farmer-managed natural regeneration in the Sahel has greened millions of hectares essentially by protecting trees that resprout from existing roots. The trees were already there; people simply stopped cutting them.
What should I ask before donating to a tree-planting charity?
Two questions. Was this land forest before? And what is your five-year survival rate? A serious organization will answer both immediately. An organization that cannot answer the second one did not measure it, and usually did not want to.
Are tree-planting offsets legitimate?
They can be, but they require verification that most do not have. Ask for year-five survival audits and confirmation that the land was previously forested. Without those, an offset is a receipt for a photograph.
Is afforestation slow?
Yes, and honestly so. Carbon accumulates in a growing forest over decades. Project Drawdown classifies it as a delayed solution. We call it a generations solution, because slow is not the same as useless. A tree planted today is a gift arriving in eighty years, and that has always been an acceptable trade.
Sources
- Project Drawdown - Tree Plantations on Degraded Land (Drawdown Explorer) Framework and classification. Cited, not reproduced.
- Veldman et al. (2019), Science - Comment on the global tree restoration potential
- Holl & Brancalion (2020), Science - Tree planting is not a simple solution
- IUCN - Forest Landscape Restoration
- World Resources Institute - Farmer-managed natural regeneration in the Sahel
The solution taxonomy follows the framework popularised by Project Drawdown. The analysis above is our own; for their carbon modeling and rankings, visit them directly.