Trees could help us with the climate and biodiversity crises, if we let them
Trees lock away carbon dioxide as they grow and planting more of them could help us reach net zero emissions by 2050. Here environmental scientist Dr Cat Scott, from the Leeds Ecosystem, Atmosphere & Forest Centre, examines the challenges being faced by forests around the world and what we need to do in the UK to maximise the benefits of new woodland creation.
The scale and pace of change required for society to avoid a dangerous level of climate change is unprecedented in our history; those caught up in recent fires and floods around the world might argue that we’ve already failed. The goal of the Paris Agreement is to limit warming to less than 1.5 degrees (above preindustrial levels) and we’re already at around 1 degree.
To avoid exceeding 1.5 degrees, scientists from the Intergovernmental Panel on Climate Change (IPCC) estimate that we need to halve our emissions of carbon dioxide in the next decade and reach net-zero emissions by 2050. The potential role of nature-based solutions, such as tree planting, in the net zero part of this plan will be one of the important topics for discussion at the upcoming COP26 summit.
Globally forests need to grow in size but are facing multiple threats
Every year around half of the carbon dioxide released as a result of human activities is taken up by the land and ocean biospheres; the ecosystems that remove the most carbon from the atmosphere per area are tropical forests.
However, the ability of these forests to continue absorbing and storing carbon is threatened, not only by deforestation and degradation but by climate change itself. Research from the University of Leeds demonstrated that rainforests in the Amazon and across Africa are already losing their ability to sequester and store carbon due to an increase in the rate at which the trees are dying. In fact, these tropical forests can handle rising temperatures up to a point, but only if they are preserved intact and have time to adapt. Beyond carbon, loss of tropical forests can also disturb regional water cycling and warm the local climate.
To explore the level of climate change the world is likely to experience in the future, and the impacts of that change, researchers use scenarios that combine different potential options in terms of energy generation, food production and land-use change. The scenarios that are able to limit warming to 1.5 degrees assume an immediate curtailing of greenhouse gas emissions but also that the planet has up to an extra 10 million square kilometres of forest by 2100 than it does now — that’s equivalent to one quarter of the current forested area. In the future scenarios, these new forests are being relied upon to take carbon dioxide out of the atmosphere and help society reach a point of net-zero emissions — but, the longer our emissions remain high, and the warmer the planet gets, the more difficult this will become for the forests.
Forests provide us with one of the clearest links between the climate and biodiversity crises the world faces. Whilst the destruction of natural ecosystems can harm both climate and biodiversity, we must ensure that our efforts to reach net zero consider these issues in parallel and find solutions that work for climate, wildlife and people.
The UK needs to ramp up woodland creation for the sake of our climate, biodiversity and health
Here in the UK we have the lowest level (13%) of woodland coverage in Europe. As part of its commitment to reach net zero, UK Government has set a target of creating 30,000 hectares of new woodland per year by 2025. In recent years, UK planting rates have fluctuated between highs of around 13,000 hectares (e.g., 2019–2020) and lows of less than 6,000 hectares (e.g., 2015–2016) per year; this gives us an idea of how challenging reaching the new target will be. Research from the University of Leeds demonstrates that as well as tree planting, natural regeneration of native woodland can make an important contribution to these targets.
Coniferous trees, dominated by the non-native Sitka spruce grown to provide timber, occupy around half of the UK’s woodland area. Despite this, the UK does not currently produce enough timber to meet domestic supply needs. Whilst increasing woodland area in the UK provides the opportunity to strengthen the timber supply chain, it is critical that we also diversify our woodlands, restore the balance between native and non-native tree species, and reverse recent declines in woodland bird, insect and plant species numbers.
The inevitable challenge in a small country like the UK is balancing domestic food and fuel production requirements with what is best for conservation and climate. The new Environmental Land Management schemes aim to reward farmers and land managers for the generation of public goods, but with these schemes still in the pilot phase, many land managers are unable to act.
The ongoing pandemic has highlighted the important role that access to nature plays in our physical and mental well-being. With less than one-third of UK woodland in public ownership, the creation of new forests should increase levels of accessibility to nature across both urban and rural regions of the country.
Local areas will need to match net zero ambitions with finding suitable land for trees
Leeds lies within the White Rose Forest, the community forest that spans West and North Yorkshire and occupies a substantial part of the proposed Northern Forest. Our work at the University of Leeds aims to help the local authorities in the White Rose Forest set ambitions for tree canopy cover expansion that are in line with national and regional net zero targets. To do this we are quantifying their current levels of tree coverage and estimating how much carbon could be taken up if woodlands were expanded. Our previous work with Leeds City Council identified that the city currently has around 17% tree canopy cover and that this would need to double by 2050 for Leeds to contribute to woodland creation in line with net zero advice from the Climate Change Committee.
Rather than being targets to check off as they are met, these local ambitions are designed to inform a conversation around how we get from where we are now to a situation in 30- or 50-years’ time where we have contributed to limiting warming to a safe level, and we have healthy, accessible, ecologically diverse woodlands for people and wildlife to enjoy. With these ambitions set, the challenge becomes finding land that is suitable for new trees and woodlands, and ensuring that as many people as possible benefit from their planting and protection.
What can we do?
Ultimately, to protect the world’s forests we must drastically reduce our greenhouse gas emissions so that we do not push them into a climate in which they cannot cope. At the same time, to reach net zero emissions and limit the amount of climate change the planet experiences, we must do all we can to preserve and strengthen the capacity of ecosystems to lock up carbon.
Globally, nationally and locally, we need policies that protect trees and forests from disturbance and facilitate the creation of new woodlands. At an individual level we can all contribute by supporting local woodland creation and restoration plans and, if you have space, planting a (regionally appropriate) tree in your own garden. Here in Yorkshire, projects like Wild Ingleborough aim to tackle both the climate and biodiversity crises by expanding the iconic Ingleborough National Nature Reserve and restoring degraded land from the valley floor to the top of the mountain (find out how you can get involved here). However, it’s crucial that we do all this alongside taking steps to reduce our greenhouse gas emissions and give these trees the chance they need to help.
Further Information
The Leeds Ecosystem, Atmosphere and Forest (LEAF) centre at the University of Leeds brings together forest-related research and activities from across campus. LEAF links the University with external organisations, such as local authorities, charities, government departments and the media, helping to ensure that our research has a tangible and beneficial impact on the world’s forests and their communities. Stay up to date by following us on Twitter.
You can also find out more about the University of Leeds at COP26 and the research being undertake at Leeds going towards achieving net-zero emissions.
Image credit: Green tree under blue sky by Baciu Cristian Mihai on Unsplash
