Planting trees is not enough to save the planet
While planting trees can be good for all sorts of reasons, relying on tree-planting to save the planet might not be one of them – they may even do harm if planted incorrectly, reports Steve Boggan
On 11 November 2019, an army of environmentally conscious Turks planted 11 million saplings at more than 2,000 sites across their country. In Corum province, 303,150 were put into the ground in just one hour – a feat that made it into the Guinness Book of Records. As a demonstration of peoples’ desire – or need – to do their bit to combat climate change, it was a beautiful thing. The trees would grow and as part of the process of photosynthesis, they would absorb carbon dioxide, the primary cause of global warming.
Three months later, however, Turkey’s agriculture and forestry union claimed that 90 per cent of them were dead. The union’s president, Sukru Durmus, said the saplings had died because they were planted at the wrong time of year, had not been sufficiently watered and because planting trees was a job that should be carried out by experts, not enthusiastic amateurs.
It was an echo of a similar tree-planting failure in the early years of a Chinese initiative aimed at halting the advance of the Gobi Desert. The Three-North Shelterbelt Project – begun in 1978 – would see a ribbon of billions of trees running 2,800 miles along the length of the encroaching desert in northern China, a “Great Green Wall” that would hold it back. Tonnes of seeds were dropped by plane and millions of saplings planted by hand, but an analysis conducted by scientists in 2011 found that as many as 85 per cent of them had perished because they were the wrong variety for the environment in which they were expected to grow.
China has carried on planting trees there – an estimated 70 billion so far – and it will continue with the project until 2050. This is called “afforestation”, a process that involves planting trees where there were previously none, and it has to be a positive thing to do, right? Well, not always. If the afforestation occurs on land that can’t support it, the trees will suck that land dry, potentially making the problem worse.
“[It’s like what the] American farmer did to cause the dust bowl in the 1930s,” Xian Xue, an expert on desertification at the Chinese Academy of Sciences in Beijing told National Geographic magazine in a 2017 interview. “People crowded into the natural sand dunes and the Gobi to plant trees, which caused a rapid decrease in soil moisture and the groundwater table. Actually, it will cause desertification [in some regions].”
If you find these stories depressing, you might be one of the millions of people worldwide who have paid for trees to be planted as a way of offsetting their carbon footprint. Because while planting trees can be good for all sorts of reasons, relying on tree-planting to save the planet might not be one of them.
“People are very connected to trees and love them, and that’s a good thing,” says Simon Lewis, professor of global change science at University College, London. “But too often the justification for tree planting as a solution to climate problems is a mix of distorted science and political convenience, mostly to try and continue with business as usual in the face of the obvious need to reduce emissions, and reduce them fast.”
In the last week of March, Nasdaq launched the world’s first commodity index for tracking the price of removing carbon dioxide from the atmosphere. It will follow the cost of a variety of Carbon Removal Certificates, or Corcs – tradeable digital assets representing a tonne of CO2 that has been removed.
When you go to a piece of land, it’s already got some vegetation on it and it’s already got some carbon stored in the soil, but when you clear all that to plant your monoculture plantation, that carbon is released into the atmosphere
The launch was the latest development in the growth of a burgeoning carbon-offset market which, according to Mark Carney, former Governor of the Bank of England (and now vice-chairman of a Canadian asset management company), will be worth £100bn by the end of the decade. As governments and companies scramble to meet carbon emission reduction targets set in Kyoto, Paris and Glasgow, the prospect of offsetting emissions by buying carbon credits is becoming massive business.
In much the same way as Medieval Catholics could buy papal indulgences to cleanse their souls and clear a path to heaven, companies can buy into schemes that supposedly cancel out the environmental damage that their operations do to the atmosphere. And, because it is easier than cutting CO2 emissions, planting trees has become the favoured method for attracting absolution among some governments and corporations.
According to a 2015 report in the journal Nature, there are just over 3 trillion trees on the planet. There are 12 zeros in a trillion, so it’s easier to comprehend that number if it’s written out in full as Three thousand billion. And because these trees absorb, or sequester, carbon dioxide and give off oxygen, they represent a natural weapon in the fight against climate change.
As a result, enthusiasm has grown to plant more and more of them. In January 2020, the World Economic Forum launched its One Trillion Trees Initiative, with the aim of growing, saving or restoring trees across the planet. There is also Trillion Trees, a collaboration of a number of conservation groups headed by the Wildlife Conservation Society and the World Wildlife Fund. And there is the Trillion Tree Campaign organised by German-based Plant-for-the-Planet foundation.
However, some scientists are warning that planting trees may not be the panacea the world is looking for. In fact, unless the right trees are planted in the right places for the right reasons, they could do more harm than good.
According to the Intergovernmental Panel on Climate Change (IPCC), about 730 billion tonnes of carbon dioxide must be removed from the earth’s atmosphere by the end of the century if the 1.5C limit on global warming set by the 2015 Paris Agreement is to be met. That, according to a 2019 paper co-authored by Professor Lewis, is equivalent to all the CO2 emitted by the United States, the United Kingdom, Germany and China since the birth of the Industrial Revolution.
“No one knows how to capture so much CO2,” says the paper, entitled Restoring natural forests is the best way to remove atmospheric carbon. “Forests must play a part. Locking up carbon in ecosystems is proven, safe and often affordable. Increasing tree cover has other benefits, from protecting biodiversity to managing water and creating jobs.
“The IPCC suggests that boosting the total area of the world’s forests, woodlands and woody savannahs could store around one-quarter of the atmospheric carbon necessary to limit global warming to 1.5C above pre-industrial levels. In the near term, this means adding up to 24 million hectares of forest every year from now until 2030.”
In order to encourage such tree-planting, in 2011 the German government and the International Union for Conservation of Nature launched the Bonn Challenge, which invited nations to pledge to reforest 350 million hectares of deforested landscapes by 2030.
At the time Lewis’s paper was published, 43 countries had pledged almost 300 million hectares – and the number of countries pledging today has risen to seven. However, the professor and his co-authors, fellow climate researchers Charlotte E Wheeler, Edward TA Mitchard and Alexander Koch, discovered that 66 per cent of all the land pledged was slated to become commercial plantation or forestry while only 34 per cent would be allowed to grow, undisturbed, into natural forests – and that was highly significant.
“When people hear about reforestation, they imagine new, beautiful forests, more like natural regeneration than industrial monoculture,” says Lewis. But when we looked at what governments were pledging in terms of forest restoration, around 45 per cent of the area globally was going towards monoculture plantations, mostly for wood production and pulp and paper, and 21 per cent would be commercial forestry.
“When you go to a piece of land, it’s already got some vegetation on it and it’s already got some carbon stored in the soil, but when you clear all that to plant your monoculture plantation, that carbon is released into the atmosphere. You have one species, and you plant it in rows. As these trees grow, they do take carbon from the atmosphere and store it in their trunks and their roots and their leaves. So, it looks like there’s a big carbon sink, a big carbon uptake – and there is, temporarily.
While planting trees is often framed as an immediate point of action for climate change mitigation as economies pursue long-term decarbonisation, our findings provide empirical evidence for the need to temper these expectations
“But when you cut all those trees down, all of the carbon from the dust and offcuts eventually go back into the atmosphere over a few years when they decompose or are burned. The wood is usually made for chipboard or pallets or cheap furniture and most of that is pretty disposable. These days, many items of furniture are designed to last a few years and then be replaced. In turn, they are burned or decompose and release more greenhouse gases.
“In contrast, if you have a naturally regenerating forest and simply leave it, that will keep carbon locked up for the long term, as long as it’s not disturbed, as long as it’s not cut down. When we published our paper, there was quite a lot of shock that governments were pledging publicly that they were going to reforest all this land when, in reality, they were allowing it to be used for short-term industrial commercial plantations and forestry.”
Lewis’s team concluded that if all 350 million hectares of the pledged land were left to grow as natural forest – the cheapest and easiest option – the amount of carbon the trees on it would sequester by 2100 would be 42 billion tonnes. Over the same period, 350 million hectares of monoculture plantation would sequester just 1 billion tonnes – but the pledges were being treated as if they were the same.
There is a wealth of evidence to show that well-meaning tree-planting projects often result in less carbon-reduction than expected. In March, in an article for Grist, the non-profit climate-reporting website, the journalist Kate Yoder explained how America’s first carbon offsetting enterprise ended in fiasco.
“In 1987, an executive at the energy company AES Corporation had the idea of trying to cancel out 40 years of CO2 emissions from its coal plant in Connecticut by planting trees in the mountains of Guatemala,” writes Yoder. “It was the first ‘carbon offset’ project – and while it sounded fine in theory, it didn’t go exactly as planned.
“As farmers in the region started planting trees, they weren’t growing as many crops as they used to and started running low on food. Then, before the 40-year project was over, the locals began cutting down the trees for fuel and lumber. In 2009, one study calculated that the programme had only offset about 10 per cent of the coal plant’s emissions.”
Tree-planting projects can be fraught with unintended consequences. Mexican farmers used to be paid by their government to care for jungle on their land, but in 2018 the Mexican government introduced a $3.4bn programme called Sembrando Vida (Sowing Life), which rewarded farmers for planting trees for fruit or timber instead. It was a scheme intended to help the country meet its carbon-reduction promises while also providing employment for impoverished farmers.
The intentions were good, but the scheme, which pays 420,000 farmers the equivalent of £162 a month, resulted in many recipients clearing precious jungle so that they could plant trees on the land instead.
“In many cases people said, ‘Well, I have my hectare of jungle but the programme is coming so I’ll cut down the jungle, use the trees for my house or to sell the wood or whatever, and when the programme comes, I’ll sow seeds again,” Sergio Lopez Mendoza, an ecology and conservation professor at the University of Science and Arts of Chiapas, told Bloomberg journalist Max De Haldevang.
According to the Washington-based non-profit World Resources Institute (WRI), which has collaborated with the Mexican government to monitor results, satellite imagery indicated that the scheme resulted in the loss of about 73,000 hectares of forest in 2019 alone.“That’s an area almost the size of New York City,” wrote Haldevang. “It’s also nearly half the average annual amount of forest coverage lost due to land-use change and illegal logging in the same region, according to WRI calculations.”
Last year, a group of environmental experts, led by Professor Eric Coleman of Florida State University, published a report in Nature which concluded that decades of tree-planting projects in northern India had been a costly waste of time as they had failed to expand forest cover or provide support for local people.
The group found that: “These plantations occur in densely settled [agricultural] landscapes, where a variety of existing land uses limit spaces available for further tree plantations. As a result, most tree planting happens within areas that already have some tree cover, limiting the potential regrowth opportunities. Planting in cleared areas is not a viable alternative because of socioeconomic and ecological constraints of converting agricultural lands back to forests.”
They concluded: “While planting trees is often framed as an immediate point of action for climate change mitigation as economies pursue long-term decarbonisation, our findings provide empirical evidence for the need to temper these expectations. Policymakers and advocates should not assume tree planting programmes will effectively meet their carbon sequestration … goals.”
The danger as governments rush headlong into tree-planting schemes is that they will adopt a casual disregard for what is really needed: drastic reductions in carbon emissions, increased use of renewables, a rapid end to the use of fossil fuels and a renewed focus on better insulation for homes in colder climates.
The government is very keen to meet the planting targets but it is all about delivery, and that’s much more complicated, much more challenging, because it’s about human behaviour
“If something seems too good to be true – in this case that planting trees is going to solve the climate crisis – then it almost certainly is,” says Charlie Kronick, senior climate adviser at Greenpeace UK. “Planting trees is a great thing to do. It enhances biodiversity, it helps protect soil and it provides good protection against flooding. And you will remember from biology class that trees are part of the carbon cycle – they sequester carbon dioxide and they generate oxygen.
“Unfortunately, we’ve got two different problems that we need to solve. One is we need to reduce carbon emissions from our reliance on fossil fuels, and the other is that we need to restore and replace the forest that we’ve lost to deforestation, whether that’s been destroyed by agriculture or animal feed or palm oil.
“The big scam of greenwashing, of offsetting, is claiming that planting trees will solve the problem. It won’t, and if you plant the wrong non-native species and grow monoculture plantations in the wrong place, you can adversely impact biodiversity without getting even close to solving the climate problem. The simple fact is that we must reduce carbon emissions by moving away from fossil fuels, switching to renewables and turning to electric vehicles, but that’s harder than just planting trees.”
But what if tree-planting were conducted perfectly, with the right trees in the right places for the right reasons? What proportion of the 50 billion tonnes of greenhouse gases emitted globally each year could tree-planting offset?
“That’s difficult to assess, but the most authoritative estimate has come from the Science Base Targets initiative [SBTi],” says Kronick. “The SBTi provides international accreditation to corporates and governments after assessing whether their climate change plans are good or bad, and it says that tree planting could offset just 5 to 10 per cent of greenhouse gas emissions generated each year.”
The UK government has pledged to plant 1.5 billion trees by 2050. Some grants to encourage landowners to do this have already been put in place – £8,500 per hectare for planting, followed by £200 a year per hectare for 10 years – but other schemes have yet to be priced and implemented.In order to ensure British tree-planting is done correctly, not only to sequester carbon dioxide but also to boost biodiversity and counter flood threats, UK Research and Innovation, sponsored by the Department for Business, Energy and Industrial Strategy, last year launched six research projects costing £10.5m, collectively called the Future of UK Treescapes Programme.
The programme is overseen by two “Treescapes Ambassadors”, Dr Julie Urquhart of the University of Gloucester, and Professor Clive Potter of Imperial College, London. Potter said efforts would be made to avoid mistakes made in the 1960s, 70s and 80s when tax breaks for tree-planting resulted in vast areas of land being planted with rows of single species of trees in huge blocks, a practice that was neither aesthetic nor good for biodiversity.
“We have some of the lowest concentrations of woodland in Europe, and we’re going to have to address that,” he says. “It’s a huge task and we have to make sure that we do it correctly, not only to help meet our carbon-reduction targets, but also to improve the biodiversity of the countryside. Visually, the levels of tree-planting planned will significantly change the way the country looks – there will be fewer wide-open spaces and more dense forests. It will be quite striking.”
Potter says it won’t simply be a matter of allowing farmers and landowners to plant willy-nilly – that could result in damage to peatland or bog or hay meadow. And efforts will be made to create unified corridors of woodland in order to provide better habitats for plants and wildlife.
“A lot will be in the detail of where you put these trees in the landscape, and that is certainly a knowledge gap,” he says. “We need to know more about where you locate the woodlands in a farm landscape context – which fields you would allocate, whether they would be contiguous and how the edges of these woods would blend into the rest of the countryside. We don’t talk enough about forest or woodland design, and we should.
“The government is very keen to meet the planting targets but it is all about delivery, and that’s much more complicated, much more challenging, because it’s about human behaviour. You need to persuade the farmers, the private landowners, the charities such as the National Trust and Woodland Trust, and the commercial sector, to do the right thing and you need to co-ordinate all their actions.
“So, it’s about the rigour. The desire, the ambition, is good, and I support it, but I think it’s ultimately how we deliver on these targets in the next five to 10 years.”
We can only hope that academics, farmers, landowners, the private sector and, ultimately, the government get it right – because they won’t get a second chance.
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