There is black gold beneath the UK’s moors and mountains; not crude oil, but peat, a substance that can absorb and retain huge quantities of atmospheric carbon. It is estimated that around three billion tonnes of carbon is stored in UK peatlands at present – more than the forests of Britain and France put together. But our hills are slowly being eroded, and upland soils are now producing greenhouse gases at an alarming rate.
Peat bogs are found on every continent, from the tropics to the tundra. In the UK, we have around 75 per cent of the world’s heather moorland – a rich, yet endangered source of peat – and 10 to 15 per cent of the global area of blanket bog.
A recent report by Moors For The Future, a partnership funded by Heritage Lottery, in collaboration with scientists at Durham and Manchester Universities, suggests that pristine UK peatlands have the potential to absorb 400,000 tonnes of carbon a year.
The report warns, however, that UK peatlands damaged by drought, fire and erosion could actually emit up to 381,000 tonnes of carbon a year. While peat uplands in Scotland still appear to be absorbing carbon, those in England and Wales are faring much worse. Bogs in the South Pennines, in particular, are badly eroded due to the historical stresses of industrial pollution, and are now releasing alarming amounts of carbon into the atmosphere.
Peat forms when moorland vegetation – particularly sphagnum moss – becomes trapped in waterlogged ground. In the absence of sufficient oxygen to allow decay, the organic matter can remain virtually unchanged for centuries – hence the discoveries of ancient boats, human bodies and even intact trees within peat bogs that have been excavated.
In many ways blanket bog, the most common type of peatland in the UK, has a lot in common with crude oil. Unlike trees, which eventually decay and release their carbon stores, the vegetation locked away in peat acts more like a fossil fuel. As long as it doesn’t decompose, the stored carbon largely remains trapped in the soil.
Central to this delicate balance, however, is the soil moisture content, which has been declining for years.
History repeating itself
The damage probably began as far back as the Middle Ages, with localised overgrazing. Vegetation loss exposes peat to the elements. Once dry, the vegetation within begins aerobic decay, and carbon dioxide is released. Erosion also carves out deep gullies, which further increase soil erosion. Vegetation loss has been accelerated by two centuries of industrial pollution, with some areas of upland peat becoming too acidic to support even ericaceous moorland plants such as heather and bilberry.
Wetland drainage began in earnest during the Roman occupation, but latterly gained pace in the ‘feed Britain’ era following World War II. Government grants funded the mechanical ploughing of drainage channels, or ‘grips’, over 1.5 million hectares of moorland, to improve the land for stock grazing and to support larger grouse populations. The scientific rationale behind the project was poor, however, and neither goal was achieved.
From the 1970s, moorland overgrazing was encouraged by Common Agricultural Policy subsidies linked to farm productivity, worsening erosion damage. Mercifully, the recently introduced Single Farm Payments scheme could help halt the decline and significantly reduce moorland grazing densities. Some areas of particularly badly damaged moorland are now wholly livestock-free and the new subsidy scheme also rewards landowners for conservation activities such as gully-blocking.
Since 1976, there have been more than 350 wildfires on Peak District moors. One of the biggest, on Bleaklow in April 2003, left in its wake nearly 850 hectares of bare peat, which soon became badly eroded. Spring 2007 in the Peak District saw widespread moorland closures due to the risk of wildfires – the ground and vegetation were tinderbox dry. Rangers were posted to access points to divert walkers and acted as an early warning system when several fires broke out.
These wildfires are occurring with greater frequency as climate change increases periods of spring and summer drought, followed by heavy rain. Human activity may also be to blame in other ways: the majority of fires originate next to footpaths, suggesting careless or reckless behaviour on the part of outdoor enthusiasts who should know better.
A healthy and active peat soil should act as a net carbon sink. In addition to carbon dioxide released through aerobic decomposition when the water table is low, peat loses carbon via particulate erosion from its surface – through footpath erosion, gullying and fire damage – and as dissolved organic carbon (DOC) into streams and gullies. Around 40 per cent of DOC is returned to the atmosphere as carbon dioxide.
Dr Fred Worrall, of Durham University, has been studying DOC levels in UK rivers for decades. His view is that levels began to rise 40 years ago and are now increasing by some six per cent a year. According to his studies, 77 per cent of those areas he has examined show a significant increase in carbon loss, and he sees our changing climate as a primary issue: ‘The frequency of summer drought and wildfire is certainly increasing. The worst possible scenario is a dry summer, which hastens aerobic decay, followed by a wet winter, which then flushes out dissolved organic carbon.’
Carbon loss from soil may be further exacerbated as greenhouse gas levels rise. Researchers at the University of Wales, Bangor, recently discovered that elevated atmospheric carbon dioxide levels accelerate bacterial decay in peat bogs, causing stored carbon to be discharged into streams and amplifying the effects of climate change. Given that peat soils worldwide are estimated to hold 30 per cent of terrestrially stored carbon, urgent action is needed literally to stop the rot.
Efforts are underway to mend the damage that has already been done and to prevent further erosion by regulating grazing and burning by landowners. Restoring peat bogs that actively sequester carbon will be a much tougher objective, though.
In addition to these factors, much of the upland heath in the UK is managed for grouse shooting. Rotational burning of heather during the winter months – at intervals of at least 12 years – helps regenerate denser, more lush vegetation. This provides better food and shelter for grouse. Damage to peat is minimised if this is done with care and while the peat is moist. This has apparently not always been the case – and new legislation designed to reduce erosion caused by bad management came into force on 1 October 2007. This limits the area to be burned, with tighter restrictions on steep, easily eroded slopes and next to watercourses.
In the South Pennines, Moors For The Future staff and volunteers have, over the past few years, spread heather ‘brash’ – shredded vegetation from healthier areas of moorland – on to approximately 600 hectares of peat that have been exposed by fire. This helps stabilise the soil, helping heather seeds from the brash to germinate, and reintroduces vital mosses, lichens and fungi. Steeper slopes are stabilised with expanses of jute netting; ascending the Pennine Way from the Woodhead Pass towards Bleaklow Head now feels a little like walking on a giant patchwork quilt.
So far, the project has proved successful in meeting its primary aims, with some areas revegetated by as much as 93 per cent. This should limit surface erosion, but may not be enough to restore the peat to an active state.
Raising the water table is crucial to recreating blanket bog conditions. Gully-blocking – often using simple dry-stone walls – can help keep peat moist, although the effect upon the water table is purely a local one. Gully-blocks also trap large amounts of sediment, which would otherwise be washed away.
Upland peat should act as a natural sponge, instrumental in preventing flash-flooding in low-lying areas such as York. While much attention was given to the problems facing our flood plains this summer, few people may have considered the importance of such upstream factors.
Getting to grips with the issue
The Northumbria Regional Flood Defence Committee has made the connection, and is helping to fund the Peatscape project in the North Pennines. Drainage ditches are dammed using peat blocks that are cut by hand or using a low-impact digger. This is slow and costly work. There are an estimated 10,000km of grips to block in the North Pennine area alone, and permission to do so must first be granted by the landowner.
The problem is how to pay for the work elsewhere. One way for upland restoration to generate some of its own funding could be through the emerging carbon-offset market – though this is not as straightforward as it might first appear.
Trading upland carbon gains as certified emissions reductions could finance moorland restoration on a large scale. Unfortunately, the precise emission savings of blocking a gully or a grip are hard to quantify – unlike tree-planting, for which better data is available. As Fred Worrall points out, there are other complications, too.
‘The UK Government is not required to account for soil carbon losses as part of its current emissions total,’ he says. ‘In order to obtain the financial benefits of emission-reducing moorland restoration schemes, carbon dioxide loss from upland soil would have to be included in the first place.’ Given the accelerated rate of carbon loss from peatlands, it is easy to see why the Government would be less than keen on doing so.
Voluntary offsetting, according to Dr Worrall, seems a more likely solution – one he believes is very close to becoming a reality: ‘While planting a tree may appear a more tangible outcome for someone wishing to offset their personal emissions, peat restoration has a significant advantage – trees store carbon temporarily, but peat can truly act as a carbon sink.’
Restored, active peatlands across the UK could sequester carbon equivalent to the emissions of 84,000 family-sized cars per year. At present, we are a very long way from achieving that ideal.
Changing our ways
Raising awareness of the vulnerability of our peatlands is both essential and urgent. If visitors can be educated to tread carefully on the hills, there is no reason we should not continue to do so. Facilities such as the new Moorland Centre at Edale, Derbyshire, encourage visitors to explore these precious landscapes, but to do so with respect for their fragility. Tourism also provides a valuable stimulus for the many rural communities facing economic decline, yet whose involvement in conservation is vital.
The Pennine Way stretches 268 miles from the Peak District to the Scottish Borders. The contrast between the deeply scarred south and relatively intact north of the range is stark. This damage was wrought through centuries of pollution and neglect, but patterns of climate change now look set to make matters much worse. Rising temperatures are causing carbon to drain from the moors into waterways at an escalating rate.
Heather moorland is certainly worth preserving for its unique character and its stunning biodiversity – but we humans often need something more tangible to make us truly listen. So whether it is through the effects of our changing climate, the colour or the cost of our tap water as DOC levels rise, or simply the possibility that lowland flooding may affect our homes, people in the UK may soon be feeling the effects of what is happening far away on those bleak, windswept moors.
Trevor Critchley is a chemistry teacher, freelance writer and hillwalker