3Soil carbon and climate change
Carbon emissions from soil degradation
29. Soil is a vital store of carbon. If it is badly managed, it can be a major source of greenhouse gas emissions.62 An estimated 9.8 billion tonnes of carbon are stored in Britain’s soils.63 Indeed, soils store three times as much carbon as is contained in the atmosphere, and degradation of carbon-rich soils releases significant quantities of CO2.64 The British Society of Soil Science told us that if soils are not managed for carbon storage then climate change could be “heightened”.65 Heath Malcolm said that greenhouse gas emissions from soil were 22.29 million metric tonnes of CO2 equivalent (MtCO2e) in 2013. The Committee on Climate Change notes that emissions from soil are “higher than for many industrial and energy sources, for example petroleum refining (14.7 MtCO2e), concrete production (6 MtCO2e) and the chemical industry (5.2 MtCO2e)”. However, as Heath Malcolm told us, “under some circumstances soils can increase their carbon stocks and act as a sink for CO2”—so gross emissions from soil do not tell the whole story. Greenhouse gas removals by soil from the atmosphere amounted to 15.5 MtCO2e in 2013, meaning that the net emissions from soil were 6.75 MtCO2e—1.45% of the UK’s total emissions.66 Greenhouse gas emissions are estimated to account for around half of the economic cost of soil degradation.67
30.Professor David Powlson noted that the large stock of carbon already in soils is significant and should be managed carefully:
Because you have this big stock in the world soils already, it is both an opportunity and a threat. It is a threat because you might lose some of that stock, and so deforestation, draining of peat soils have been talked about. These are all things that lead to release of carbon from this big stock. I now put more priority in a sense of looking after those places where we have big stocks. Don’t drain peat, absolutely minimise deforestation. [ … ] You have to be very careful to preserve and keep those places where you already have big stocks.68
31.Defra also commented on the importance of soil in relation to climate:
Soil plays a critical role in regulating our climate, as the biggest terrestrial carbon store. Increasing the resilience of soils to the impacts of climate change allows them to continue to deliver the societal, economic and ecosystem benefits they provide.69
Declining soil carbon in arable and peat soils
32.Organic carbon levels are crucial to soil health and the ability of soil to deliver ecosystem services.70 The Soil Association told us, for instance, that “everything from long-term yields and the quality of food grown, to resilience to extreme weather and soil erosion” depends on carbon levels.71 ADAS UK expanded on the importance of soil organic matter, which is the dominant component of soil carbon:
Organic matter provides a food source and habitat for the soil biological community, drives the cycling of nutrients within soils and is a central component of soil aggregation and the maintenance of structure and water relations. It is therefore widely recognised that soil organic matter is fundamental to the maintenance of soil fertility and function, and a key indicator of soil quality.72
33.Because of this, as the 2007 Countryside Survey notes, “all soils need to retain carbon”. However data shows that while overall organic carbon levels have generally remained static, there has been a significant decline in carbon levels in in arable and peat soils.73 The National Soil Inventory found a decrease of 5 grams per kilogram in arable soil carbon between 1978 and 2003.74 The Countryside Survey records that, between 1978 and 2007, the topsoil carbon concentration in arable soils fell by 11%. The bulk of this reduction was observed between 1998 and 2007.75
34.Loss of carbon from soil has negative consequences, as Mistra EviEM outline:
On farmland that is harvested regularly, decline in carbon content can result from organic compounds being broken down, being removed in crops, or eroded. If the stock of soil carbon is degraded, then the atmospheric concentration of carbon dioxide can change.76
35.The Committee on Climate Change warns that organic carbon loss may contribute to decline in agricultural yields, and that some loss is caused by land management practices. In their Statutory Progress Report to Parliament on preparing for climate change (2015), the fertility of agricultural soils was given a ‘red’ rating to signify that progress is not being made to manage the vulnerability. They said that Defra should take action to deliver its policy aspiration for all soils to be sustainably managed by 2030.77
Peatland degradation
36.Because the UK’s peatlands store around 40% of our soil carbon78, they are especially important. Natural England research published in 2010 shows that 57% of England’s soil carbon is stored in lowland Fens.79 The research also found that the majority of England’s peatlands are currently net sources of greenhouse gases, with lowland peats being particular hotspots for emissions. Some upland peats are still capturing carbon (i.e. taking in more than they emit), but even among upland peats most are net sources of carbon emissions rather than net sinks for carbon. ADAS UK told us that deep peats in upland areas support semi-natural habitats and are most important for carbon storage and climate regulation. STARS doctoral students told us that healthy peatlands also “provide cleaner and cheaper water by filtering rainfall before entering waterways”.80 Wildlife and Countryside Link added that “runoff from degraded peat soils also negatively affects water quality”.81
37.The National Trust told us that the health of peat determines whether it is a carbon store or sink. They said that “practices (e.g. drainage or burning) designed to increase its productivity for particular enterprises, have unintended consequences”. They added that “eroding peat soils will lead to sediment in watercourses and discolouration, the latter requiring costly treatment before being used as drinking water”.82 Newcastle University said that “The decomposition of peat removes one of the most efficient carbon sinks on the planet and has massive implications for feedbacks to the global climate system.”83
38.The British Ecological Society notes that there is “widespread degradation to UK peatland soils by drying through loss of sphagnum [peat moss], gripping, erosion, gullying and burning (both managed and wildfire).” Other witnesses also raised the issue of burning on upland peats as a damaging practice.84 The Committee on Climate Change commented on upland peats, pointing out that 14% are eroding, 18% have been drained, and 27% are regularly burnt.85 An example is the burning of blanket bogs on Walshaw Moor in West Yorkshire.86
39.The Committee on Climate Change also explained how land management practices have contributed to peat degradation and that this may lead to the loss of agricultural land:
Some of the most productive agricultural land in England is at risk of becoming unprofitable within a generation due to soil erosion and the loss of organic carbon. Without further action, farmers may not benefit from the opportunities of longer growing seasons, and the natural environment will be severely harmed by climate change.87
40.They also noted how peats have degraded in the Fens and the implications of this:
The loss of peat soils in The Fens has been occurring for hundreds of years. Today, only around 16% of the peat stock recorded in 1850 remains. [ … ] The rate of peat loss has been between 10mm to 30mm a year. Climate change is expected to accelerate these losses, with every 1°C rise in temperatures increasing the rate of loss by 30%. As a result, all the remaining deep peat soils in the Fens could be lost within the next few decades.88
41.The Soil Association note that “the communities in and around The Fens are reliant on agriculture either directly or indirectly”, and that “while peat is complex to farm, this land is generally more profitable per hectare and carries a significantly higher land value than most arable soils.”89 Peat which is degraded becomes “wasted”, usually leaving a thin layer of soil known as “skirtland”.90
42.The Wildlife Trust for Lancashire, Manchester & North Merseyside told us that peat soils in Alt-Crossens (a large catchment between the Mersey and Ribble estuaries) have been degraded by land-use policy over a long period, and that this may result in the loss of peat soil from the catchment by 2040. They claim that cost-benefit analyses underlying peat management policies have not accounted for the ecosystems services provided by peat soils.91
43.Wildlife and Countryside Link said that there is a “strong argument for ceasing agricultural production on [ … ] deep peat to ensure that carbon remains locked in these soils”.92 However, The CCC said that reversing the trend of degradation might not necessarily require ceasing agricultural production on peats:
In the Fens and other areas of lowland deep peats, it would be possible for some form of agricultural production to continue in ways that conserve the peat resource. Reverting from intensive arable systems to extensive wet grasslands would conserve the peat and not increase CO2 emissions. Other potentially viable alternatives that would potentially conserve peat are the production of perennial biomass crops and agro-forestry. 93
These ideas for reducing peat degradation will be informed by new data on peat emissions that we understand is currently being reported to Defra.94
44.The CCC expanded on how peat could be restored:
Degraded peatlands can be restored, through measures such as blocking drainage ditches, re-seeding bare peat and reducing adverse management practices such as intensive burning and over-grazing. There is increasing evidence from field studies that restoration reduces carbon losses, both as CO2 and [dissolved organic carbon], as well as delivering biodiversity and landscape benefits. A number of water companies operating in the English uplands have been investing in peatland restoration in recent years to help reduce the carbon content in raw water, and therefore lower the costs of drinking water treatment.95
45.The Soil Association call for the Government to set up a special climate and soil protection area covering the remaining deep peat in the Fens, with a target of reducing greenhouse gas emissions from the area by 80% by 2050. This echoes the recommendation of the 1996 Royal Commission on Environmental Pollution report, that “remaining areas of original lowland bog and fen habitat in the UK be strictly protected.”96 The Soil Association also called for “farming systems to conserve rather than degrade peat; and alterations in the drainage systems to help safeguard peat soils”.97 They said:
It is impossible completely to halt the loss of these peat soils, but there are a number of actions that would dramatically reduce soil losses and greenhouse gas emissions. In other areas where farming has had an unacceptable impact on the environment and public interests, EU legislation has ensured that coordinated, often geographically defined action has to be taken, for example in Nitrate Vulnerable Zones or in implementing the Water Framework Directive through Catchment Sensitive Farming.98
46.Defra’s Natural Environment White Paper (2011) stated an aim to “undertake a research programme over the next four years [into, among other things,] how best to manage our lowland peatlands in a way that supports efforts to tackle climate change. We will use the results of this research to set the direction of future action.”99 The most recent implementation update (Oct 2014) states that five research projects are underway, with two due to report in 2014 and three in 2016.100
47.Rory Stewart, Parliamentary Under Secretary of State at Defra, told us that the Government plans to improve the state of peatland. “[T]he objective is to begin to gently reverse the decline; so halt first and then make it better. We would like to get a situation where at the end of our planned period there is more healthy peat in the country than there is today.” He described actions that are being taken to achieve this, including: protecting peat under Sites of Special Scientific Interest legislation; buying out peat works to stop extraction; reseeding peat bogs; and blocking inappropriately laid drainage ditches.101 He noted that actions will be focused on ‘bare peat’ which, if left alone, would release much carbon into the atmosphere. Defra also reported progress between 2003 and 2013, with 97% of peatland blanket bog SSSIs being either in either “favourable” or “unfavourable but recovering” condition. Defra described this as a “major step forward” in the restoration of degraded peats. However, the Parliamentary Office of Science and Technology note that peat areas that are not SSSIs are “generally not covered by restoration schemes and are at risk of further damage”.102 Natural England have also found that there no difference between the rate of managed burning on SSSI and non-SSSI peatlands.103
Action to improve soil organic matter
48.Some witnesses called for targeted action to increase the level of organic carbon in soil. The Soil Association calls for a specific commitment of 20% increase in the next 20 years:
Based on the widespread evidence from organic farming, we are calling for the UK Government to commit to increasing [soil organic matter] levels by 20% in the next 20 years in arable soils–a relative increase of just 1% a year. This is similar to the French Government’s 4/1000 - ‘4 pour mille’ initiative, announced at the Paris climate summit - a plan to increase global levels of soil organic carbon in all soils by 0.4% each year, in order to make a significant contribution to the offsetting of greenhouse gas emissions (a ‘4 per thousand’ target).104
49.Defra has expressed support for the French initiative, noting that it joined the plan at COP21, and saying that “even a small increase in the soil carbon stock [ … ] is crucial to improve soil fertility and agricultural production and to contribute to achieving the long-term objective of limiting the temperature increase to 1.5/2°C.”105 Defra’s written submission did not indicate what action would flow from this, instead saying only that “this is being used as an opportunity to highlight research and good practice that has been carried out in the UK”. We asked Rory Stewart, Parliamentary Under Secretary of State at Defra, how the goal would be achieved. He said that “our investments in peatland, grassland and agricultural soils” would increase soil organic matter. He added that the biggest contribution would be likely to come from peatland.106
50.Rory Stewart expressed confidence about the possibility of success in this area, saying that “we know how to improve soil organic matter”. Peter Melchett (Soil Association) echoed this, telling us that methods to increase organic matter, and thus soil carbon, are already established. However, he noted that governments had not always recognised the need for action:
How you get carbon back into soil is fairly settled science, I would say: you use green cover crops in the winter, you do not leave the soil exposed, you use, where you can, crops with deeper roots so you have more biomass to put back into the soil. You put the crop waste, the straw, ideally through a cattle shed and then it is farmyard manure or compost back into the soil. You use rotations that include grass, exactly as you say, because that will help. It is not rocket science. What seems to be very difficult is to get Governments of all parties to recognise the problem and to recognise the need for action. It is becoming more urgent. The potential is huge, we could put huge amounts of carbon back into soil.107
51.The Committee on Climate Change argued in 2015 that an action plan was required to address these issues:
Defra should take action to deliver its policy aspiration for all soils to be sustainably managed by 2030, publishing an action plan within a year of this report to describe how the goal will be achieved. The action plan should include proposals for establishing a scheme to monitor the uptake of soil conservation measures, with enforcement where soils are not being appropriately managed. The action plan should include specific proposals to reverse the ongoing loss of lowland peat soils, and be developed in partnership with the farming sector.108
Rory Stewart told us that the action plan on peat would form part of Defra’s upcoming 25-year environment plan.109 He regarded work on bare upland peats to be “low hanging fruit”, with lowland peats involving more difficult trade-offs with economic activity.110
52.Soil organic matter content and carbon levels are central to the ability of soil to provide essential services to society. Soil also has to the potential to help mitigate climate change: it should be part of the solution, not part of the problem. Carbon losses pose a threat to the sustainability of food production, with some of the most productive land in England at risk of becoming unprofitable within a generation due to soil erosion and loss of carbon. The imperative to increase carbon levels in soils is clear, and there is widespread agreement on how organic matter and thus carbon levels can be improved. Despite this, data shows that carbon levels in arable soils have been declining. For the Government to meet its ambition for all soils to be managed sustainably by 2030, and to ensure agricultural resilience and minimise the effects of climate change, urgent action is required to reverse this trend and increase carbon levels in all soils. If significant amounts of soil carbon continue to be lost into the atmosphere then this will make it harder and more expensive to keep temperature increases well under 2 degrees as set out in the Paris Agreement. Every tonne of carbon maintained in soil gives greater flexibility to the rest of the economy in meeting our carbon budgets.
53.At COP21 the Government signed up to an initiative to increase soil carbon levels by 0.4% per year: as part of the 25-year environment plan, it should set out specific, measurable and time-limited actions that will be taken to achieve this goal.
54.Given the concentration of carbon in peatland soils, degradation and decline of peats is particularly concerning. Mismanagement of these soils could undermine the UK’s efforts to manage climate change. The Government should take tougher action to tackle land use practices which degrade peat, such as unnecessary burning and draining when crops are absent. It should set out what has been learned about lowland peat management from the research it undertook after the 2011 White Paper and explain how this will be used to inform future action. The Government should also step up its peatland restoration programme. The upcoming 25-year environment plan should explain what measurable and time-bound actions will be taken to first halt and then reverse peatland degradation while minimising the impact on agricultural capacity.
67 Graves et al, The total cost of soil degradation in England and Wales
68 Prof David Powlson (Q88)
70 Ecosystem services are “the benefits provided by ecosystems that contribute to making human life both possible and worth living”, as defined by the UK National Ecosystem Assessment.
71 Soil Association (SHI62). See also APPG on Agroecology (SHI40); British Ecological Society (SHI58); Karen Johnson & Jennifer Jeffes (SHI28); Lancaster Environment Centre (SHI14); Martin Rogers (Q3)
73 Countryside Survey 2007; Prof Chris Evans (SHI79); Committee on Climate Change (SHI46); AHDB (SHI75)
77 Committee on Climate Change, Progress in preparing for climate change: 2015 report to Parliament
78 UK National Ecosystem Assessment (2011) The UK National Ecosystem Assessment: Synthesis of the Key Findings.
79 Natural England, England’s Peatlands
80 Sustainable Use of Soil, The Royal Commission on Environmental Pollution, 1996
86 Hebden Bridge Times, ‘Walshaw Moor grouse shoot at centre of legal action over blanket bog burning’
87 Committee on Climate Change, Progress in preparing for climate change: 2015 report to Parliament
88 Committee on Climate Change (SHI46); See also Prof Chris Evans (SHI79) for discussion of the ‘16% remains’ figure.
90 Cranfield University, An estimate of peat reserves and loss in the East Anglian Fens
94 SP1210, Lowland peatland systems in England and Wales-evaluating greenhouse gas fluxes and carbon balances
95 Committee on Climate Change (SHI46). CCC told us that water companies investing in peatland restoration include Yorkshire Water, United Utilities and South West Water.
96 Sustainable Use of Soil, Royal Commission on Environmental Pollution, 1996
99 The Natural Choice: securing the value of nature, Defra, 2011
101 Rory Stewart Q249
102 Securing UK soil health, POST, 2015
103 Natural England, The effects of managed burning on upland peatland biodiversity, carbon and water
106 Rory Stewart (Q239/240)
107 Peter Melchett, Q45
108 Committee on Climate Change, Progress in preparing for climate change: 2015 report to Parliament
109 Rory Stewart, Q257-258
110 Rory Stewart, Q260
© Parliamentary copyright 2015
27 May 2016