Soil beneath our feet holds key to tackling climate crisis

The World Congress of Soil Science being held in Glasgow could be key in the global fight against climate change.
While burning fossil fuels accounts for two thirds of harmful emissions, the misuse of soil accounts for the other third but doesn’t receive anything like the attention it deserves, according to Clive Mitchell of NatureScot.
He is hoping this will change as a result of the Congress, which he describes as a “great coup” for Glasgow as it will be the first time the four yearly event has been held in the UK since 1935 when it took place in Oxford.
The Congress, from July 31 to August 5 at the SEC, will welcome around 1600 scientists to the city and Mitchell believes it presents a huge opportunity to bring soil into the limelight and make it more central in the journey towards net zero.

“The importance of soil is very much hidden and it is time we dragged it out and shone a light on it,” he said.
Perhaps because it is under our feet, we forget soil is vital for human life on earth. “We wouldn’t be here without it,” said Mitchell. “Soil is very much at the centre of the climate/nature crisis that we currently face, yet it is very much a Cinderella subject in relation to its profile in pretty much everything that we do, whether we are talking about conservation, farming, forestry, management of the uplands, development in towns and cities and so on.”
Soil should, overall, soak up carbon but is currently a net source of emissions globally and in Scotland. This is because humans have broken the global carbon cycle through the burning of fossil fuels (about 70%) and land use change (about 30%).
Peatlands are drained and degraded, deer suppress peatland and woodland restoration, woodlands are mostly commercial plantations, grasslands for livestock are mostly fed by synthetic fertilisers, the lowlands are mainly mono-cropped by heavy machinery with most of the trees and hedges removed, flood plains are prevented from flooding, urban areas have little greenspace especially in poorer areas, coastal habitats such as salt marsh, seagrass and kelp have been diminished and the seabed is widely disturbed. Landscapes are largely 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 in a matter of years. For the climate, these releases are catastrophic.
Land-based emissions result from systematically degrading ecosystems through progressive simplification from more biodiverse to less biodiverse systems, including monocultures and drainage especially of wet carbon-rich soils.
Healthy soils, which are diverse and function effectively, are essential to a healthy climate-nature system.
Mitchell points out that to reach net zero and to maintain it we have to fix the “green and blue” parts of the carbon cycle. 
Fixing the “black” bit (fossil fuels) is vital, but no amount of heat pumps or electric vehicles will fix the green and blue parts so we have to transform the way we use all land and sea for farming, fisheries and forestry.
In Scotland, soils are a massive carbon store, holding more than 3,000 million tonnes of carbon, of which 53% is held in deep peatland soils. This is about 60 times the amount of carbon held in the country’s trees and plants, making soils the main terrestrial store of carbon – and it’s important we keep it there.
In Scotland, around 30-40% of the transition to net zero is going to be concerned with the land. 

“Not burning fossil fuels is vitally important but it only gets us two thirds of the way to net zero and the other third is in how we use the land and the soil,” said Mitchell.  
“That is a really important point to recognise if we are going to make our contribution to getting into the lower end of the Paris target range of 1.5-2oC. That is where the Scottish Government’s ambition quite rightly is, but it is going to require massive transformations in how we use the land so that it does become a net carbon sink.”

One way or another, land and sea use will change. If the world chooses a +2oC world – and it is a choice – the changes are largely out of human control, driven increasingly by the impacts of a changing and chaotic climate, imposing escalating loss and damage costs to people and planet.
However in a 1.5oC world the changes are more in human control. This “no-regrets” pathway is by far the least costly to people and planet. Taking this path requires re-wetting and restoring peatlands while making commercial and conservation woodlands more diverse and resilient. 
Agroforestry would be the norm, with more hedges and farmland trees, and intercropping to control pests. Farms would mix crops and extensively graze livestock, riverbanks would be wooded and flood plains allowed to flood.
There would be more greenspace in towns and cities to manage surface water, enhancing local nature and sequestering carbon. There would also be more extensive and diverse marine habitats and less disturbance of the seabed to ensure both productive fisheries and more resilience in marine biodiversity undergoing a long recovery from acidification. Sea levels would still continue to rise but both coasts and rivers would be recognised 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 programme and many examples of farms that use regenerative practices – ie those that improve soil health, increase biodiversity and sequester carbon through the use of practices such as cover crops, crop rotations, minimal tillage, organic fertilisers, agroforestry and crop-livestock integration.
However, it should also be recognised that not only must the use of the 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, drought, pests, disease and pandemics. A changing climate impacts nature and its associated services more severely the simpler and more degraded it is.
Soil health and more diverse nature not only builds resilience to these events, it makes them less likely by correcting disruptions to carbon, nitrogen and other key cycles. 
“Farming, forestry and the diversity of species that we use to grow food is key to building resilience to the impacts of climate change, which of course includes pathogens and diseases in natural systems, crop systems and woodland systems as well as human systems – as we have seen recently with the pandemic,” said Mitchell.
“Our current food systems are producing high sugar, high fat, energy dense foods which are not very good for population health and rely on production systems that are degrading soils and nature and contributing to climate change. 
“We need to shift both what and 
how much we eat so that our diets contribute to both population and planetary health.”

Mitchell maintains that there is space for meat in a net zero world but it would have to be from a production system more focused on integrating livestock and arable systems, with more emphasis on organic fertilisers while also fitting the breed to the capacity of the land. In a Scottish context that might mean using efficient but smaller breeds. 
The environmental cost of production should also be reflected in price, according to Mitchell.  
“There really is an important job to do in marrying up sustainable production with sustainable consumption,” he said. 
“That relationship between the price of goods and the cost to society and the planet is vitally important. 
“To avoid problems of leakage you would have to ensure there was a carbon tax applied at borders to carbon intensive goods so that it covers both the things produced within the country as well as the imports. 
“That reduces the risk of leakage so you don’t have goods that are produced at a cost to the environment competing with sustainable domestic products.”
Mitchell believes that Scotland has a good story to tell at the 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 leads the way on efforts to restore peatlands.
“The Scottish Government has put £250m into that over ten years and it is widely recognised that this is a good start, although we probably need to pretty much double that by 2030 and find ways to attract private finance to match or surpass the amount of public money that is going in..
“However we now know how to restore them and create conditions where we can secure private money in a much less risky environment. Through peatland action and some of the vision for agriculture we are moving more into that regenerative space for healthy soils that life depends on,” said Mitchell.

This article is not necessarily representative of the views of the Herald