Can planting more forests really help avert climate disaster? Etan Smallman looks into the Government’s plans
Photo: Angela Redmon
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Does the solution to climate change grow on trees? It is a question many in Cardiff and Ceredigion may be asking themselves this week after the Welsh government announced that every household will be offered a free native species tree – which people can nurture in their own gardens or have added to woodland on their behalf.
Such planting initiatives have become increasingly central to the world’s efforts to combat our environmental emergency, with oaks and spruces removing carbon dioxide from the atmosphere and storing it in vegetation and the soil.
Councils in Glasgow, the host city for last month’s COP26 climate talks, promised to plant 18 million trees in the next decade. The woody plants made up a quarter of one of Boris Johnson’s key mantras ahead of the summit – “coal, cars, cash and trees” (a slogan that even made it into his former aide Allegra Stratton’s tearful doorstep resignation speech this week).
The Government committed to planting 11 million trees in England between 2017 and 2022. And last year, the World Economic Forum launched its One Trillion Trees Initiative to conserve, restore and grow that number by 2030, though critics have described it as “a form of magical thinking”.
For Dominick Spracklen, professor of biosphere-atmosphere interactions at the University of Leeds, the discussion is a hardy perennial, which too often ends up devoid of nuance.
“There is no one silver bullet to solve climate change,” he tells i. “Planting trees without doing anything else will be a complete disaster.
“There’s nothing wrong with announcing a big tree-planting effort. We know in the UK we need to increase our woodland tree cover to meet net zero targets. We know we need to do it to restore biodiversity. But we need to remember that we need to protect our ancient woodlands at the same time.”
The latter may seem a much less sexy proposition to politicians than the roll-out of brand new forests. But massive old trees store massively more carbon than fresh saplings. One tree with 100cm diameter can store as much as three tonnes of carbon – more than 100 times as much as a younger tree with a 10cm diameter.
Our ancient woodlands – areas continuously wooded for centuries, perhaps even since the last ice age – cover only 2.5 per cent of the UK, but are exceptional in terms of biodiversity value. While they are under threat from the likes of nitrogen pollution, roads and railways and invasive species such as rhododendron, the Woodland Trust has said the protection they are afforded “is currently too weak” and their role attracts too little attention from policy makers.
A new analysis completed for the State of the UK’s Woods and Trees 2021 report found that although ancient and long-established woodlands only make up about a quarter of British woodlands, they lock up more than a third of the total carbon stored.
Spracklen says, where possible, creating the conditions for forests to naturally regenerate themselves is the best option. But when it comes to planting, our motto must be “right tree, right place”. He favours native species and warns against monocultures that are not resilient against disease and climate change itself.
In the 1970s and 1980s, the Flow Country vast expanse of blanket bog in the North of Scotland was planted with fast-growing conifers, degrading the peatlands that draw large quantities of carbon from the atmosphere.
That is a disaster we have learnt from, but today, says Spracklen, “across the UK, you’ll see these plastic tubes go up and then next year they’re all blown over and that’s not going to create a woodland. That’s just creating a load of plastic mess.”
Some experts argue that we should be thinking out of the (timber) box. Hemp can capture atmospheric carbon much more effectively than forests, says Dr Darshil Shah, a senior researcher at the University of Cambridge’s Centre for Natural Material Innovation.
“Because hemp can be grown in such large densities and because it grows rapidly, it is able to capture up to two times more carbon,” he says.
A type of cannabis plant, hemp can be grown in many parts of the UK and can also provide carbon-negative biomaterials for everything from insulation for homes to interior door panels for cars.
“The key with many of these plant-based materials is you want to ensure that the carbon is locked in the structure for as long as possible rather than being released back into the environment [through rotting or burning], therefore using them in long life-span applications is critical,” says Shah.
As with everything when it comes to nature, we need to take the long view. The cheap, easy and headline-grabbing bit is the planting of trees. But, says Spracklen, the local community must be involved from the start as they are the ones who need to care for the trees and protect them from pests and other threats for generations to come if the new forests are to play any sustained role in tackling our carbon woes.
Of course, trees offer us so much more than natural “carbon sinks” – including recreation, quality of life, urban shading and protection of wildlife. But their majesty must not stop us from seeing the wood for the trees, especially while greenhouse gases are still wreaking global havoc and we have not yet managed to end deforestation. You cannot simply plant your way out of a climate crisis.