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With Europe’s deadly summer heatwave still fresh in the mind, scientists from around the world are gathering in Glasgow to focus on the vital role soils play in maintaining a healthy ecosystem and halting climate change, writes Nan Spowart
The World Congress of Soil Science being held in Glasgow could be the key in the global fight against climate change.
While burning fossil fuels accounts for two-thirds of harmful emissions, land abuse accounts for the other third, but doesn’t get anywhere near the attention it deserves, according to NatureScot’s Clive Mitchell.
He hopes this will change as a result of the congress, which he describes as a “major coup” for Glasgow, as it will be the first time the quadrennial event has been held in the UK since 1935 when it took place in Oxford.
The convention, from July 31 to August 5 at the SEC, will welcome around 1,600 scientists to the city, and Mitchell believes it presents a huge opportunity to bring soil into the spotlight and make it more central to the journey towards net zero.
“The importance of soil is very hidden and it’s time we drag it out and shine a light on it,” he said.
Perhaps because it is under our feet, we forget that soil is essential for human life on earth. “We wouldn’t be here without it,” Mitchell said. “Soil is very much at the center of the climate/nature crisis that we’re currently facing, but it’s very much a Cinderella topic in terms of its profile in pretty much everything we do, whether we’re talking about conservation, agriculture, forestry, management of the highlands, development in towns and so on.”
Overall, soil should absorb carbon, but is currently a net source of emissions globally and in Scotland. This is because humans have broken the global carbon cycle through burning fossil fuels (about 70%) and changing land use (about 30%).
Peatlands are drained and degraded, deer suppress peatland and woodland restoration, woodlands are mostly commercial plantations, grasslands for livestock are mostly fed synthetic fertilizers, lowlands are mainly mono-cropped by heavy machinery with most trees and hedges removed , floodplains are prevented from flooding, urban areas have little green space, especially in poorer areas, coastal habitats such as salt marshes, sea grass and kelp are reduced and the seabed is greatly disturbed. Landscape is mostly simple.
As a result, carbon that would normally be stored for hundreds or thousands of years in soils and sediments, or millions of years in fossil fuels, is returned to the atmosphere within a few years. For the climate, these emissions are catastrophic.
Land-based emissions result from the systematic degradation of ecosystems through progressive simplification from more biodiversity to less biodiversity, including monocultures and drainage, especially of wet carbon-rich soils.
Healthy soil, which is diverse and functions efficiently, is essential for a healthy climate-natural system.
Mitchell points out that to reach net zero and to sustain it we need to fix the “green and blue” parts of the carbon cycle.
Fixing the “black” bit (fossil fuels) is important, but no amount of heat pumps or electric vehicles will fix the green and blue bits, so we need to change the way we use all our land and seas for farming, fishing and forestry.
In Scotland, soils are a huge carbon store, containing more than 3000 million tonnes of carbon, 53% of which is in deep peatlands. This is about 60 times the amount of carbon held in the nation’s trees and plants, making soil the most important terrestrial store of carbon—and it’s important that we keep it there.
In Scotland, around 30-40% of the transition to net zero will be taken up by the country.
“Not burning fossil fuels is very important, but it only gets us two-thirds of the way to net zero, and the other third is in how we use the earth and the soil,” Mitchell said.
“That’s a very important point to recognize if we’re going to make our contribution to getting into the lower end of the Paris target range of 1.5-2oC. That’s where the Scottish Government’s ambition is quite right, but it’s going to require massive transformations in how we use the land so that there is a net carbon sink.”
In one way or another, the use of land and sea will change. If the world chooses a +2oC world – and it is a choice – the changes are largely beyond human control, driven increasingly by the effects of a changing and chaotic climate, with escalating loss and damage costs for people and planet.
But in a 1.5oC world, the changes are more in human control. This “no regrets” path is by far the least costly to people and the planet. Taking this path requires rewetting and restoring peatlands, while making commercial and conservation forests more diverse and resilient.
Agroforestry would be the norm, with more hedgerows and agricultural trees, and intercropping to control pests. Farms would mix crops and extensively graze livestock, riverbanks would be forested and floodplains allowed to flood.
There will be more green space in towns and cities to manage surface water, strengthen local nature and sequester carbon. There will also be more extensive and diverse marine habitats and less disturbance of the seabed to ensure both productive fisheries and more resilience in the marine biological diversity that undergoes a long recovery after acidification. Sea levels will still continue to rise, but both coasts and rivers will be recognized and managed as dynamic systems.
Some examples of current practice show that the potential for transformation exists, such as the Scottish Government’s Peatland Action program and many examples of farms using regenerative practices – i.e. those that improve soil health, increase biodiversity and sequester carbon through the use of practices such as e.g. cover crops, crop rotation, minimal tillage, organic fertilizers, agroforestry and crop-livestock integration.
However, it should also be recognized that not only must the use of land and sea contribute to and maintain net zero, it must be resilient to inevitable changes.
These consequences include increased frequency and intensity of floods, fires, droughts, pests, diseases and pandemics. A changing climate affects nature and its associated services more strongly the simpler and more degraded it is.
Soil health and more diverse nature not only builds resistance to these events, it makes them less likely by correcting disturbances in carbon, nitrogen and other key cycles.
“Agriculture, forestry and the diversity of species that we use to grow food are key to building resilience to the impacts of climate change, which of course includes pathogens and diseases in natural systems, cropping systems and forest systems as well as human systems – as we’ve seen recently with the pandemic,” Mitchell said.
“Our current food systems produce high-sugar, high-fat and energy-dense foods that are not very good for population health and rely on production systems that degrade soils and nature and contribute to climate change.
“We have to change both what and
how much we eat so that our diet contributes to the health of both the population and the planet.”
Mitchell argues that there is room for meat in a net zero world, but it must be from a production system that is more focused on integrating livestock and arable systems, with more emphasis on organic fertilizers while adapting the breed to the capacity of the land. In a Scottish context it may mean using efficient but smaller breeds.
The environmental costs of production should also be reflected in the price, according to Mitchell.
“There is really an important job to do in combining sustainable production with sustainable consumption,” he said.
“This relationship between the price of goods and the cost to society and the planet is very important.
“To avoid problems of leakage, ensure that a carbon tax was imposed at the borders of carbon-intensive goods, so that it covers both things produced in the country as well as the imports.
“It reduces the risk of leakage, so you don’t have goods produced at a cost to the environment competing with sustainable domestic products.”
Mitchell believes Scotland has a good story to tell at Congress.
“We have world-leading expertise in people like Professor Pete Smith at Aberdeen University, who is lead author with the Intergovernmental Panel on Climate Change for their work on soils and land use,” he said. “And Scotland is leading the way in peatland restoration.
“The Scottish Government has put £250 million into this over ten years and it is widely recognized that this is a good start, although we probably need to double this by 2030 and find ways to attract private finance to match or exceed the amount of public money that goes in..
“But we now know how to restore them and create conditions where we can secure private money in a much less risky environment. Through peatland actions and some of the vision for agriculture, we are moving more into the regenerative space for healthy soil that life depends on,” Mitchell said.
