The risks of climate change now need little introduction. We are already starting to live with the impacts of a changing climate on the environment, communities, businesses and supply chains.
To have even a fifty-fifty chance of limiting global heating to 1.5°C, the world must reduce CO2 emissions to net-zero by mid-century, with an emissions decline of around 40-50% achieved by 2030.
While many countries – including the UK – are now committed to achieving net zero by mid-century, even in the most ambitious reduction scenarios, cumulative greenhouse gas emissions over the coming years are likely to overshoot that critical 1.5oC goal, according to Intergovernmental Panel on Climate Change’s (IPCC) most recent report. The answer – or at least part of it – may lie in significant carbon dioxide removals (CDR) – and not only as an adjunct to emissions reduction, but as an essential part of its removal.
One of the key categories of CDR includes what is known as “Natural Climate Solutions”, which will deliver CO2 sequestration through the restoration of nature and the improved management of existing land uses. These solutions rely on photosynthesis – primarily of trees – to capture and store CO2, and in some cases, enhance that sequestration for longer-term or even permanent storage. A vital part of this afforestation and reforestation solution includes commercial forestry.
THE ROLE OF TREES IN REACHING NET-ZERO
With many technology-based CDR solutions in their infancy, tree planting is – at least for the time being – the only scalable “negative emissions” strategy. And it comes with additional benefits for biodiversity, wildlife, flood management, health, not to mention considerable employment, production and trade opportunities.
Afforestation and reforestation are crucial to help meet the UK’s climate targets. Trees use CO2 in the process of photosynthesis to feed their growth for which they then store the carbon, ideally in a permanent cycle. Existing trees and forests are one of the most important stores of carbon on the planet. In the UK, for example, forests currently hold 3.7 billion tonnes of carbon – estimated to be the equivalent of 10 years of the UK’s annual emissions.
NOT ENOUGH TREES
Current afforestation in the UK is a fraction of what it was a few decades ago, falling from a peak in the 1970s and 1980s when planting for wood fibre was heavily incentivised by the UK government.
This in itself was a response to centuries of widespread deforestation. At the turn of the 20th century, the country had just 5% of forest cover, with felling being intensified further during the first world war. This prompted the creation of the Forestry Commission, which purchased land for woodland expansion and began the process of reversing the trend.
Today, however, the UK still has only 13% forest cover – with only 7% of native woodlands in good ecological condition – compared with almost 40% in continental Europe.
After years of declining tree-planting rates and with carbon accumulation falling as UK woodlands mature, the rate of absorption is projected to fall in the coming years. In 2020, the annual rate of CO2 accumulation by UK forests was around 18 million tonnes, but according to Forest Research, this is forecast to decline to around 10 million by 2040.
The Conservative government led by Boris Johnson had pledged to plant 30,000 hectares (75,000 acres) of new woodland every year by 2024 – but official statistics recently released show less than 14,000 hectares were planted in the year to March 31, 2022. Scotland planted three-quarters of the total with 10,480 hectares, with England planting 2,260, Wales 580 and Northern Ireland 540.
CHOOSING THE RIGHT TREES
Not all trees grow at the same rate or absorb CO2 in the same way. Faster-growing, coniferous tree species – which make up the majority of productive woodlands – sequester carbon much more quickly in the early to medium term. And far more carbon is absorbed in mature conifers (40-50 years old) than in slower-growing broadleaf tree species at the same age. However, broadleaf species can accumulate more carbon reserves in the longer term – so between 50 and 100 years.
In order to determine the productivity of trees to absorb carbon, the UK forestry industry, as well as the Climate Change Committee (CCC), uses a “yield class” measure to indicate how much wood (measured in cubic metres per hectare) is added through growth each year. As the added wood is made up of carbon there is a link to speed of growth and the ability to sequester carbon more quickly.
For example, broadleaf trees generally grow with a yield class of between four to eight (the CCC give an average yield as seven for broadleaves), meaning they grow four to eight cubic metres per hectare per year. Oaks grow at around six, wild cherry at eight and poplar achieves rates of up to 12.
While the CCC also assumes an average yield class for conifers of 13 – based on research from 2003 – it is now accepted within the forestry industry that based on improvements in tree breeding and silviculture in recent decades, this figure is too low and should be a yield class of 16 or higher. Some recently planted forests that include fast-growing Sitka spruce have been measured as high as 44.
Essentially, these yield classes paint a picture of conifer species playing a vital role in locking up carbon quickly and meeting planting targets.
It needs to be emphasised, however, that simply planting vast forests of conifers may not be the best solution, despite their high productivity in capturing carbon. It would fail to take into consideration the other opportunities and benefits a more diversified mix of productive and broadleaf planting can deliver, including improving biodiversity and wildlife habitats.
WHAT NEEDS TO BE DONE
The CCC recommends increasing woodland cover in the UK from 13% to a minimum of 17% by 2050 with a 60-40 split of broadleaf to conifers – and ideally, to 19% to ensure the country achieves net zero carbon emissions. Such an increase equates to about 1.5 million hectares of additional woodland.
But with the need for carbon capture now so urgent, Confor has gone one stage further, proposing a 50-50 split between broadleaf and conifer planting. In a generic calculation, it estimates that if 18,000 hectares were planted every year starting this year, by 2030 these trees would sequester 2.04 MtCO2e, of which over 1.7 MtCO2e would be stored by conifers alone.
Meeting these planting rates will require a significant and rapid scale up of the forestry sector to meet several urgent priorities. These include identifying space within the nursery sector to grow saplings, the manpower to undertake actual planting and subsequent management.
When looking at where to plant, this will inevitably result in some compromise, as the competing needs of agriculture, wildlife and the general public need to balanced. Nevertheless, according to Carbon Brief, an unpublished Forestry Commission analysis has identified 3.2 million hectares of low sensitivity areas for planting trees in England alone. Referred to as “low risk areas for woodland creation,” they comprise areas that do not fall into categories such as higher quality agricultural land, special conservation areas and deep peaty soils, as well as not being close to protected areas.
Indeed, the CCC concluded in its most recent land-use report that 22% of agricultural land must be turned over to carbon sequestration if the net-zero goal is to be achieved. This would include peatland restoration and energy crops, as well as afforestation. In this scenario, the committee said farmland would be released as a result of reductions in meat and dairy consumption, increased farm efficiency and reduced food waste.
The problem with the CCC scenario is that it is just that – a scenario. In today’s reality, the main issue is accessing this land and incentivising landowners to turn enough of it over to forestry in large enough numbers.
Much of the productive planting is likely to be on land currently grazed for sheep. Analyses have shown that this land would provide greater income to the owner and support just as many jobs locally if it was planted with productive forest. And in terms of food security it is interesting to note that the UK is producing 109% of the lamb it consumes against the backdrop of declining demand.
In Scotland, a Woodland Expansion Advisory Group was established bringing together farmers, foresters, government and agencies. It identified a “deep cultural divide” between farmers and foresters. Convincing farmers and other land owners to also become foresters will require a change in culture and policies that facilitate the integration of farming and tree planting.
There are many factors for landowners to take into consideration – perhaps most importantly, earnings from growing wood which may not be seen for several decades. As well as high-level guidance and mapping of which areas should be targeted for tree planting, the current grant scheme in England needs to be slicker – tree planting is highly regulated and it can take years to get approval to plant. An additional barrier might be that tenant farmers that operate on around a quarter of land area, may be prevented for using their land for purposes other than agricultural.
THE GIFT THAT KEEPS ON GIVING
While forests act as a carbon store in the landscape, its product – timber – can also be a permanent store when used in construction and manufacturing, meaning the felling of trees when used in the building and furnishing industry isn’t the end of the story.
Carbon remains stored in wood products harvested from forests, and these can often substitute for non-renewable construction materials such as concrete and steel. Recent research suggests that for every tonne of carbon sequestered in a new wood product, about 1 tonne of carbon is “saved” by avoiding the use of alternative materials. Domestically grown wood products will most likely also reduce the carbon miles accumulated in the importation of the wood we use. All in all, in addition to delivering greater carbon sequestration, a forest’s end product could significantly contribute to decarbonising the broader economy.
The potential opportunity for increasing timber as a core construction material could be significant. While 83% of Scottish house building uses timber frames, in England and Wales there are low rates of timber construction and high rates of masonry construction – accounting for 77% of new houses.
In their report “Bigger, Better Forests” think tank, Policy Exchange, called for an overhaul of the UK’s forestry sector to drive the uptake of timber in construction. It states that, compared to masonry, concrete and steel, timber can reduce a building’s “embodied carbon” by between 20-60%. The report also calls for a carbon tax on the embodied carbon in new buildings to encourage a switch to timber.
THE NEED FOR MANPOWER
After decades of under-investment, particularly outside Scotland, there is a lack of infrastructure, expertise and workforce. Five years ago, the Royal Forestry Society (RFS) identified the impending skills shortage and declining enrolment in forestry courses at UK institutions. To facilitate the scale of the forestry sector, more researchers, silviculturists, ecologists, planting, maintenance and harvesting contractors will be needed, along with considerable retraining of existing land managers who may lack up-to-date knowledge and understanding of woodland management.
A recent report from the Institute of Chartered Foresters warns that skills shortages in arboriculture and forestry are at critical levels, and a new generation is not being recruited to take over from an ageing workforce. It estimates that the industry needs to recruit 70% more people to meet planting targets set by government and the IPCC.
PUBLIC SUPPORT
At the end of 2021, Confor undertook a survey to establish the level of public support for producing more home-grown wood. In summary, over 90% of respondents were unaware that the UK imported 80% of its wood resources, yet 50% of respondents saw domestic wood production as being important – and just behind the importance of food production – with a similar number agreeing that growing more domestic timber is beneficial for the environment. A further two-thirds agreed that there should be forest expansion. Similar surveys to gauge public attitudes to forestry were also undertaken by Forest Research when there was 83% support for the planting of “a lot more trees” and 72% supporting diversified forests suited to future climates.
WRAPPING UP
The UK government, devolved administrations and hundreds of local councils have declared an unequivocal climate emergency. But we have an unprecedented opportunity to be an enabler of the net zero economy and capture much of the residual carbon beyond the steps that industry and consumers have taken to reduce emissions. The challenges are not always straightforward but the informed decisions and urgent actions we take now will have a lasting impact for decades to come.
