June 27, 2018

expert reaction to the Manchester moorland fires

A blaze on Saddleworth Moor, which measures 3.7 miles, has been raging since Sunday night.

Prof Guillermo Rein, Professor of Fire Science at Imperial College London, said:

“One phase of the fire that needs attention is when the underlaying peat in the soil of the moorlands ignites. If so, it will burn as smouldering combustion (flameless and most persistent type of fire). It is too early to tell if peat has ignited. One can tell by the abundant white smoke that does not raise to the top but that accumulates close to the ground (forming haze). Flaming combustion produces darker smoke that quickly raises up in the atmosphere. Based on previous large moor fires, it is almost guaranteed that smouldering fire will take place at some point. Smouldering is especially visible after the flames are put out. Pay attention to this because smouldering is more difficult to extinguish than flaming, the pollution episode can be severe and the damage to the moorlands ecosystem and carbon stock will be larger.

“Whereas the Fire Services in the UK are well trained and equipped in fighting wildfires, I also welcome the involvement of the Armed Forces. This is because I have experienced once before, in 2006, Scottish Highlands, the unusual approach of the Army to fight fires. They use heavy machinery to dig deep and wide trenches all around the fire perimeter so that it could not spread any further. The damage was effectively controlled and limited to the inside of the perimeter (4 hectares in that 2006 fire). We inspected the site weeks after and measured the carbon loss per unit area burnt to be 96 tons of carbon per hectare.”

Dr Bjorn Robroek, peatland researcher at the University of Southampton, said:

“Peatlands store large quantities of organic carbon. For centuries, centimetre for centimetre they have captured carbon dioxide –a greenhouse gas– from the atmosphere and locked it away as peat. In natural peatlands, the water-logged conditions is naturally protected from burning.

“Peatland management (gripping) in the UK has caused natural water tables to drop, and with the current drought these systems are vulnerable to burning. As with many wildfires, peat burns when an ignition event occurs (this could literally be anything: cigarette butt, piece of glass, natural combustion). Peatlands are high fuel ecosystems (high carbon content). These type of systems, other than low fuels systems like grasslands, typically smoulder. Peat fires can persist under low-temperatures and low oxygen contents (even in moist conditions) and burn for long periods. Interesting in this sense is that these fires can continue even when it starts to rain. We also know that these smouldering fires, besides releasing CO2 and methane, produce particulate matter.

“When wildfires happen in hydrological intact peatland, they generally result in a loss of the upper layers of the peat. In disturbed peatlands, a fires can be much deeper and peat that has been accumulated over the last 500 years can be lost. This is very important as old carbon that was previously thought to be safely locked away will be released to the atmosphere.

“Besides the loss of the carbon stock, the vegetation in these peatlands will be lost. Especially the loss of the peat moss layers, the ecological engineer and building blocks of peatlands, will result in large restoration challenges. Peat mosses are, for example, very important for the hydrological conditions in these systems, and provide a habitat and growth medium for the diversity we generally see in peatlands.”

Prof Vincent Gauci, Professor of Global Change Ecology at The Open University, Vincent Gauci, said:

“While small in comparison to the raging Indonesian peatland fires of 2015 or those regularly experienced in Canadian and Siberian peatlands, the close proximity of these peatlands to centres of human populations such as the Greater Manchester area means there’s potential here for poor air quality to affect many tens of thousands of people.

“The Saddleworth Moor, unlike those more remote peatlands mentioned, has been a sponge for regional pollutants for decades and centuries as the region was an engine of the UK’s industrial revolution. With none of the current pollution abatement strategies in the early industrial period, these moors were on the receiving end of a whole range of quite nasty industrial pollutants. So these peats are a store of past pollution, which could be remobilised in the current fires with unknown consequences for human health.

“Further, our research here at The Open University is showing that fire on peatlands can exacerbate downstream losses of dissolved organic carbon in waterways. This is therefore a potential issue for the water treatment industry, which has a hard time removing this form of carbon when making water potable.”

Prof Chris Evans, Biogeochemist at the Centre for Ecology and Hydrology, said:

On causes and human impacts:

“Almost all moorland fires are started by people – often accidentally, due to things like cigarettes or portable barbecues, but sometimes intentionally. The hot, dry, breezy conditions we’re experiencing at the moment allow fires to establish and spread rapidly, and more hot dry weather due to climate change is likely to lead to more fires – but to start a fire something (and usually someone) has to ignite it.

“This fire is close to population centres, but the direct risk to people seems to be fairly low. This isn’t always the case – for example wildfires in Portugal last year killed around 100 people. These fires also contributed to the ‘apocalyptic’ red sun that was seen in the UK during Hurricane Ophelia.

“The indirect health impacts may be more of a concern – part of what’s burning on Saddleworth Moor is peat, which is essentially immature coal, so what people are breathing in is effectively coal smoke. Forest and peat fires in Indonesia during the 2015 dry season are estimated to have caused about 100,000 premature deaths due to smoke inhalation – however those fires burned over 2.5 million hectares, compared to around 1,000 hectares so far on Saddleworth Moor, and lasted for months, so we’re certainly not talking about anything like that sort of impact here.”

On environmental impacts:

“The fire will be releasing carbon dioxide as the vegetation and peat beneath it is combusted. The carbon in the peat has accumulated over thousands of years, so releasing this to the atmosphere will contribute to global warming in the same way as burning fossil fuels. Again, during the 2015 fires Indonesia was emitting more CO2 to the atmosphere than the whole United States, so globally these fires are a really important source of greenhouse gas emissions.

“The moorlands around Manchester have been soaking up atmospheric pollution since the start of the Industrial Revolution, so there is a risk that the fires could release some of this pollution back into the air or water.

“The ecological damage resulting from major fires can be severe. The loss of vegetation cover and damage to soils can trigger erosion, the timing for ground-nesting birds is terrible, and the recovery of moorland plants is likely to be slow, particularly for the ‘wetland’ species that are critical to the ecology of peatlands. The vegetation on the moors around Manchester is still recovering from over a century of industrial air pollution, and huge efforts have been made in recent years to re-wet and restore these ecosystems, so fires like this represent a major setback to those efforts.”

Prof Susan Page, Professor of Physical Geography at the University of Leicester, said: 

“The fires are taking place in an area of upland Britain that has extensive peatlands.

“Peatlands are a globally important carbon pool. While covering only ~3% of the Earth’s land surface, they contain an estimated 500 to 700 billion tonnes (Gt) of carbon, which is between 32 and 46% of the total soil carbon pool (~1500 Gt) and likely exceeding that contained in the world’s vegetation (500 Gt). By any comparison, peat-forming ecosystems are a significant component of the global carbon cycle.  Peatlands cover 11% of England’s land area and are most extensive in the uplands, including the Peak District. They contain around 584 million tonnes of carbon.

“In peatland ecosystems, fires comprise both flaming and smouldering combustion. While flaming, surface fires consume vegetation and litter, smouldering fires burn into and below the ground consuming the peat itself as a fuel source. Flaming fires may pass rapidly through the vegetation but smouldering fires burn slowly and persist for long periods of time, burning repeatedly in response to changing soil moisture and penetrating to different peat depths.  They can also smoulder and then reignite (as we see in the Saddleworth moor fire). Smouldering combustion is a low-temperature process that proceeds under reduced oxygen availability.  Peat moisture is the main factor limiting peat ignition and the start of the smouldering combustion process and fires will not usually establish in peat with a high moisture content. The recent hot, dry spell of weather will have dried out the peat surface, but moisture content may also have been lowered by previous land drainage (e.g. to improve grazing for livestock).

“The incomplete combustion that occurs during smouldering peat fires means that they are responsible for more substantial atmospheric and air quality impacts than vegetation fires. In addition to emissions of greenhouse gases (carbon dioxide and methane), they are the source of toxic gases (e.g. carbon monoxide, benzene, hydrogen cyanide) and also high levels of small particulates (PM2.5 – particulate matter with diameter less than 2.5 micrometres). Recent research on peat fire events in SE Asia has demonstrated that this dense, toxic smoke poses significant health risks to human communities both within immediate proximity of the fires and at greater distances since smoke plumes can be transported over tens or even hundreds of kilometres from the source of the fires. This is a pertinent issue for this densely-populated regions where there is the potential for exposure of large numbers of people to smoke inhalation. This may result in an increased incidence of respiratory and cardiovascular conditions, particularly amongst children, the elderly and those with pre-existing respiratory problems. In addition, peat smoke contains many carcinogenic gases such as hydrogen cyanide, ammonia and benzene that could result in a longer-term increase in ill health and mortality in the smoke-affected population.

“For the Saddleworth Moor fire, a further concern is the industrial legacy of this region, with the peat soils containing the ‘fall-out’ from many years of heavy industry in surrounding towns and cities.  The peat soils contain this pollution legacy in the form of increased levels of heavy metals, which will also be liberated into the smoke by the fires.  Although I am not aware of any UK-based research on this issue, research in Canada has shown volatilisation of harmful levels of mercury during peat fires.”

Dr Richard Payne, Lecturer in Environmental Geography at the University of York, said:

“’The UK’s peaty moorlands are crucial for the carbon they lock away as peat. Since the last ice age these peatlands have helped cool our climate but fires can reverse that effect, rapidly returning carbon to the atmosphere as carbon dioxide. Devastating events like we are seeing today at Saddleworth Moor are likely to happen more often in the future and will exacerbate future climate change.”

Prof Fred Worrall, Professor of Environmental Chemistry at the University of Durham, said:

“The peatlands of the UK store more carbon than all other UK environments combined. By storing and taking up carbon, peatlands are helping to mitigate climate change by taking greenhouse gases out of the atmosphere. The amount of carbon stored in UK peatlands is equivalent to 35 years of the total CO2 emissions from all other UK sources.

“When wildfires occur on our peatlands they not only burn the vegetation but also burn down into the peat soils releasing all that stored carbon into the atmosphere, then after the burn the protective vegetation layers is lost and the remaining soil can be washed away. Peat soils grow at about 1mm every year (1m every 1000 years) and so even the loss of a few centimetres can mean tens or hundreds of years of growth lost.”

Prof Nick Ostle from the Lancaster Environment Centre, Lancaster University, said:

“I guess that fire is an expected hazard for these moorlands. Peatlands are massive carbon reservoirs that become tinder-boxes when they are subjected to dry spells like this.

“A challenge for local people and wildlife but not on the chart compared to massive peatland fires in tropical and sub-tropical south-east Asia.

“Luckily British peatlands are pretty resilient – it all depends on the severity of the burn.”

Prof David Rothery, Professor of Planetary Geosciences at The Open University, said:

“It’s worth pointing out that the thermal radiation from the fires is detectable from space, which is not surprising for a fire of this size.

“The MODVOLC system, an alert system for volcanic eruptions and wildfires which uses the MODIS instrument on NASA’s Terra and Aqua satellites, saw the fires on 25 and 26 June.  The satellite images show a prominent anomaly corresponding to the position of the moorland fire.”

Prof Guillermo Rein, Professor of Fire Science at Imperial College London, said:

“The UK has always had large wildfires. But their frequency is increasing. We think it is because of population increase, enlargements of urban fringes and climate change.

“There is risk in the immediate vicinity of the fire due to fast spreading flames. There is risk to large areas due to smoke pollution. UK fire services are among the best in the world. Follow their advice.

“There is a clear link between fire activity and climate change. This link is even stronger in Northern Europe.

“While small fires can be beneficial to moorlands, large and intense fires damage valuable ecosystems. It is important to keep all wildfires small.

“Smouldering peat fires are an issue in moorlands. These fires are even more difficult to suppress than flaming fires.”

Dr Rory Hadden, Rushbrook Senior Lecturer in Fire Investigation at the University of Edinburgh, said:

“Due to the hot dry weather much of the vegetation present in this kind of landscape will be very dry, particularly any of the dead/decaying vegetation on the floor of the moor. This vegetation will be very easy to ignite with even small ignition sources such as a carelessly discarded cigarette or the smouldering remains of a BBQ or campfire. Litter in the form of glass bottles and the domed bottom of a beverage can may also focus the sun’s rays and cause ignition.

“In this landscape, there are couple of aspects of fire science that are relevant. The first is the flaming fire and the second is the smouldering fire.

“The flaming fire is carried by the vegetation on the surface and any dry plant matter on the forest floor. This can spread very rapidly and the rate and direction of spread will be dependent on the wind and the terrain (slope).  The boggy nature of this landscape contains a significant amount of peat which will burn if it is dried. Given the recent weather it is likely that this peat will be very dry (at least at the surface). When peat burns it does so as a smouldering fire (imagine how a cigarette burns). This is a much slower process than a flaming fire.

“The smouldering fire poses unique challenges because even though the flaming fire may appear to be out in some areas, the smouldering can continue unobserved for many hours, days or even weeks. If the conditions are correct (wind, humidity), then this fire will transition to flaming again and the process can start again.

“The smouldering fire is generally responsible for the large quantity of smoke that is seen. This smoke consists of the products of incomplete combustion and aerosols. This can have impacts on health although there is very little research on this topic.

“Fighting these fires is hard due to the remote location. This means getting water to the scene is difficult and fire fighters will often resort to using fire beaters to extinguish the flames. This is very resource-intensive. This technique is also not effective against the smouldering fire.

“The risk to people comes mostly from the air quality issues. It is unlikely that the fire spreading in this way will impact on houses but it is possible – although unlikely – that firebrands (small burning particles) may be generated which could be transported by the wind and land in or around houses presenting an ignition risk.

“Secondary effects of these fires are significant and long term. Water quality can be affected as the run off contains the products of combustion, although I am not an expert in this area.”

Prof Alastair Lewis, Professor of Atmospheric Chemistry at the National Centre for Atmospheric Science, University of York, said:

“The current moorland fires in the UK are a relatively unusual event, but in other parts of the world biomass burning can often be the single biggest cause of air pollution that some countries face. In many parts of central Africa and South East Asia, forest fires and burning agricultural waste can create extensive and long-lasting severe air pollution events that are almost impossible to control and that have very large impacts not only on public health, but also on transport systems and industrial productivity.

“The main air pollution emissions from moorland fires are the very visible particulates and smoke along with other polluting gases that arise from partial combustion, such as carbon monoxide and benzene. Whilst some of the particles produced from burning vegetation are relatively large, and will deposit to the ground under gravity, a substantial fraction will be smaller than 2.5 microns and can enter into the lungs. The particles from this kind of burning are also characteristic in that they can carry on their surfaces a range of toxic chemicals, including a class called polycyclic aromatic hydrocarbons (PAH).  Reducing public exposure to these cancer-causing chemicals was one of the primary motivations behind the banning of stubble burning in the 1990s.

“The long-term effects of biomass burning can be modest, indeed many events are naturally triggered, and can be necessary to maintain balance in ecosystems. Clearly any climatic shift towards more periods of prolonged dry weather increases the risk of fires, and a change in frequency this kind of air pollution event has already identified as one possible consequence of a changing climate.”

Mel Harrowsmith, Head of Civil Contingencies at the Met Office, said:

“The current hot spell, along with the generally dry weather during May and June, has resulted in conditions which are favourable for wildfires across many parts of the UK.

“Although lightning strikes are frequently the cause of wildfire in other parts of the world, nearly all grass and moorland fires in the UK are started by people, such as BBQ’s left unattended, campfires, discarded cigarettes and glass.

“Poor visibility from the smoke can cause disruption to roads, railways and airports in the vicinity of fires.  With the warm and largely dry weather continuing until at least the middle of next week, conditions for wildfires will remain heightened.”

Dr Thomas E L Smith, Assistant Professor in Environmental Geography at the London School of Economics & Political Science, said:

“Of immediate concern to me is the advice from the Greater Manchester Fire and Rescue Service [as reported by the BBC] that the smoke is “not toxic”. https://www.bbc.co.uk/news/uk-england-manchester-44624021

“This is misleading, as the photos from the eastern suburbs of Manchester suggest ‘hazardous’ levels of particulate air pollution, and we have data from Manchester Piccadilly that indicates ‘unhealthy’ levels in the City Centre. People with pre-existing heart or respiratory conditions should be advised to avoid exertion. Children and the elderly, even without pre-existing conditions, should avoid exposure to the smoke in the eastern suburbs, where we can clearly see from photos that the smoke is thick.

“After a rainy and sunny spring, there has been much vegetation growth on the moorlands, providing plenty of fuel for any potential fires. The last few weeks have seen very warm and dry conditions, with the dominance of high pressure systems over the UK. Under these conditions, the vegetation, as well as the peat soil on the moors can become very dry and more prone to fires; combined with a dry continental wind, these are perfect conditions for a wildfire. While temperatures have reached 30 degrees Celsius, and relative humidity has dropped below 30%; fortunately we have not seen very high wind speeds. Under windier conditions, the fire could have spread much faster to cover a larger area. Wind speeds are forecast to remain calm for today, which should help the firefighters to maintain the situation. If the fire has ignited the peat soil though, it may be many days before the fire is extinguished as the firefighters will probably need to rely on rainfall, which is not forecast for the rest of the week.”

Prof Hugh Coe, Professor of Atmospheric Composition at the University of Manchester, said:

“High levels of particulate matter are being emitted from the large moorland fire in north Derbyshire and are affecting large areas of Greater Manchester.  In the plume peak concentrations are very high and close to the fire air quality is very poor.  Such large wildfires are common in areas of Australia, US, Canada, and many parts of the tropics but are rare in the UK.  Dry conditions during spring have left moorlands very dry and ready to ignite very quickly.

“Pollution plumes from the moorland fire that rages near Saddleworth have been detected by a team from SEES in the Centre of Manchester.  Instruments destined to be used at a new long term air quality site that has recently been funded by NERC show very high concentrations of particulates.  The measurements can identify that this very large increase is from biomass burning and hence that the moorland fire is the cause.

“Air quality measurements at the local DEFRA measurement station also show huge increases in particulate pollution during these events, with the mass of particles less than 2.5 µm in size (PM2.5) peaking at concentrations higher than 80 µgm-3.  These high levels of particulate are mixing with air that already has very high levels of ozone, formed when pollution is exposed to strong sunlight.  Both of these pollutants have significant health impacts including leading to breathing difficulties, sore throat and eye irritation.

“An informative summary of precautions you can take can be found here: https://www.manchestereveningnews.co.uk/news/greater-manchester-news/advice-people-affected-saddleworth-moor-14833106

“The new NERC funded site in Manchester will have far greater capability than the DEFRA air quality network sites that are currently being operated and will offer new insights into the causes of air pollution in our cities. More information can be found at: https://nerc.ukri.org/press/releases/2018/02-air/

Declared interests

None received.