Why planting trees won't solve the climate crisis

Mass tree planting schemes have gained popularity in recent times. But because much of this enthusiasm is misdirected, the schemes often fail and some actually do more harm than good.?

What's the point?

Trees actively remove carbon from the atmosphere as they grow and can store this carbon for long periods of time. They also support biodiversity, stabilise soil, prevent flooding and in urban areas they cool the air during heatwaves. Trees provide resources for both wildlife and humans – and they’re even nice to look at. It sounds like win-win, what’s not to like??

The number of tree planting organisations has grown nearly threefold in the last three decades. In addition, there are now at least three campaigns to plant 1 trillion trees, including the World Economic Forum’s One Trillion Trees initiative.

Mass tree planting really caught on in 2019, after a controversial study published in Science stated that restoring trees is “our most effective climate change solution to date”. It also claimed that planting a trillion trees could capture more than a third of all the greenhouse gases humans have released since the first Industrial Revolution.?

After the initial media frenzy, critiques of the study began to appear and it was even described as dangerously misleading . The study’s authors have subsequently made corrections to their original work. But the core concept has stuck around – namely, that we can plant our way out of climate change. It sounds so simple. And therein lies the problem.?

Tree planting is much easier for companies and countries to act on, compared with doing the hard work of slashing greenhouse gas emissions.

So simple, in fact, that it’s become a popular branding opportunity for companies , billionaires and even politicians .

Why tree planting isn’t the answer to climate change

First and foremost, tree planting can only offset a fraction of the carbon emissions emitted by humans each year. There aren’t enough trees in the world to offset society’s carbon emissions – and there never will?be .

The most important climate solution is reducing greenhouse gas emissions. Further, while trees can play an important part in any climate solution, avoiding deforestation is a cheaper and more effective climate solution than planting new forests.?

Planting trees will never be a substitute for decreasing fossil fuel emissions.

The largest 1 per cent of trees contain half of all the carbon. This means that while young trees planted now will be important in the future, it will take them a long time to catch up with older forests’ ability to store carbon. That is why we need to prioritise protecting and restoring existing forests.?

Not only is the carbon sequestration of new forests slow, but it is also not guaranteed over the long term. Trees only capture carbon while they are alive. Trees can die and they can burn, whether due to bushfires or being cut down for firewood. In these cases, all that carbon is returned to the atmosphere, which means the carbon captured during the tree’s lifetime has been for nothing. To keep the carbon out of the atmosphere we need long-term uses of the wood, such as in construction.?

Tree planting schemes often fail too. In Turkey, 11 million trees were planted in November 2019 as part of a mass planting effort. Three months later, up to 90 per cent of the saplings were dead.?

And there can be unintended consequences. In 2018, the Mexican government launched a $3.4 billion tree-planting campaign which paid farmers to plant trees on their land. However, in some cases it resulted in deforestation because the farmers would clear an area of forest before replacing it with seedlings.?

Tree planting can do more harm than good

Even if the trees survive, there are also some subtler problems with tree planting efforts. They often focus on single species plantings instead of restoring native forests, and this can lead to the global spread of monocultures and invasive species. There is also another factor to consider: non-native trees can consume significantly more water than natives and can deplete streams and wetlands.?

Even the best restoration projects rarely recover the full biodiversity of intact forest.?

In boreal regions, planting trees can increase warming because forests have a lower albedo (reflect less sunlight) than the snow-covered landscapes they replace.?

And then there are social and economic issues to consider. Indigenous and rural communities may cut down trees to collect firewood. In these cases, putting saplings in the ground won’t help much. A better intervention might be giving people a substitute for firewood.

Finally, planting is not always necessary. Where there are seed sources and good growing conditions, forests can regenerate on their own at a fraction of the cost and effort.?

Is there a future for tree planting??

Assuming we are already reducing greenhouse gas emissions and halting deforestation, then tree planting can be part of a climate solution.?

But restoration requires a long-term commitment of resources and many years of monitoring. We need to focus on growing trees for the long haul, protecting and restoring ecosystems and empowering the local communities that are best placed to care for them.?

We need to stop thinking about it as tree “planting”, and instead as tree “growing”.

Planting a million, a billion, even a trillion trees sounds like an ambitious target we can all get behind to help the planet. Unfortunately, it’s just not that simple.?

We are not going to plant our way out of climate change.