Carbon-releasing 'zombie fires' in peatlands could be dampened by new findings

October 30, 2020

Imperial College London researchers have simulated for the first time how soil moisture content affects the ignition and spread of smouldering peat fires, which can release up to 100 times more carbon into the atmosphere than flaming fires. They also simulated how several smaller peat fires can merge into one large blaze, and tracked the interplay between smouldering and flaming fires.

The findings could help scientists, authorities, and landowners to manage the clearing of vegetation in peatlands in the safest way possible. The study is published today in Proceedings of the Combustion Institute.

First author Dwi Purnomo of Imperial's Department of Mechanical Engineering said: "Peat fires are a devastating yet chronically under-researched phenomenon that spurt millions of tonnes of carbon into the atmosphere every year. If we can use scientific evidence to help people manage them more effectively, we can perhaps dampen their impact on people and the environment."

Peat fires, which occur in regions like Southeast Asia, North America, and Siberia, are driven by the burning of soils rich in organic content. When peat - which is a natural reservoir of carbon - burns, it releases up to 100 times more carbon per burn area into the atmosphere than non-peat fires. Worldwide, peat fires account for millions of tonnes of carbon released into the atmosphere each year.

Unlike smoke from flaming fires, which reaches high into the atmosphere, smoke from smouldering stays close to the ground, causing haze which damages human health and is associated with excess deaths in Southeast Asia.

Peat fires can start naturally by lightning strikes or by human activities, but often begin accidentally from controlled burns - flaming fires that are intentionally started to remove excess vegetation on the surface of forests or plantations.

However because they're driven by smouldering, these fires are notoriously difficult to extinguish once they get out of control. Even when flames are extinguished the fire can continue by smouldering underground and reigniting flames much later on - hence the name 'zombie fires'.

Senior author on the paper Professor Guillermo Rein, of Imperial's Department of Mechanical Engineering, said: "Although people have been using controlled burns in agriculture for centuries, starting them on peat soils can be particularly dangerous. Peat draws the fire underground, which then hides there before coming back like zombies, making detection and extinction very challenging. The effects are felt in plantations, forests, homes, residents' health and the environment." The new research demonstrates that burning vegetation on peaty soils with a high moisture content is less likely to sustain smouldering, lessening the likelihood of losing control of blazes. The findings are the first to study the interplay between smouldering peat and flaming vegetation.

The computer model could help authorities and landowners to manage the clearing of vegetation in peatlands in the safest way possible, by for example finding the right soil moisture content to avoid the ignition or spread of smouldering.

Dwi said: "It might seem trivial that drier soils sustain faster and larger smouldering fires, but this work can predict the critical moisture values for ignition."

The researchers used advanced computer simulations of smouldering and flaming fires in peatlands, and validated the simulations by comparing them to experiments. Then, they applied the model to a control burn in Southeast Asia (see video).

Dwi was inspired to study peat fires because of their abundance in his home country of Indonesia. He said: "I've seen the devastation they can cause and want to help my country and others like it which are affected by peat fires."

Next the researchers will build on their models to look for other factors that affect uncontrolled fires and in other affected regions like the Arctic.

Dwi added: "As well as soil moisture content we will look at the way rain, wind and fire-fighting affect peat fires."

Imperial College London

Related Atmosphere Articles from Brightsurf:

ALMA shows volcanic impact on Io's atmosphere
New radio images from ALMA show for the first time the direct effect of volcanic activity on the atmosphere of Jupiter's moon Io.

New study detects ringing of the global atmosphere
A ringing bell vibrates simultaneously at a low-pitched fundamental tone and at many higher-pitched overtones, producing a pleasant musical sound. A recent study, just published in the Journal of the Atmospheric Sciences by scientists at Kyoto University and the University of Hawai'i at Mānoa, shows that the Earth's entire atmosphere vibrates in an analogous manner, in a striking confirmation of theories developed by physicists over the last two centuries.

Estuaries are warming at twice the rate of oceans and atmosphere
A 12-year study of 166 estuaries in south-east Australia shows that the waters of lakes, creeks, rivers and lagoons increased 2.16 degrees in temperature and increased acidity.

What makes Saturn's atmosphere so hot
New analysis of data from NASA's Cassini spacecraft found that electric currents, triggered by interactions between solar winds and charged particles from Saturn's moons, spark the auroras and heat the planet's upper atmosphere.

Galactic cosmic rays affect Titan's atmosphere
Planetary scientists using the Atacama Large Millimeter/submillimeter Array (ALMA) revealed the secrets of the atmosphere of Titan, the largest moon of Saturn.

Physics: An ultrafast glimpse of the photochemistry of the atmosphere
Researchers at Ludwig-Maximilians-Universitaet (LMU) in Munich have explored the initial consequences of the interaction of light with molecules on the surface of nanoscopic aerosols.

Using lasers to visualize molecular mysteries in our atmosphere
Molecular interactions between gases and liquids underpin much of our lives, but difficulties in measuring gas-liquid collisions have so far prevented the fundamental exploration of these processes.

The atmosphere of a new ultra hot Jupiter is analyzed
The combination of observations made with the CARMENES spectrograph on the 3.5m telescope at Calar Alto Observatory (Almería), and the HARPS-N spectrograph on the National Galileo Telescope (TNG) at the Roque de los Muchachos Observatory (Garafía, La Palma) has enabled a team from the Instituto de Astrofísica de Canarias (IAC) and from the University of La Laguna (ULL) to reveal new details about this extrasolar planet, which has a surface temperature of around 2000 K.

An exoplanet loses its atmosphere in the form of a tail
A new study, led by scientists from the Instituto de Astrofísica de Canarias (IAC), reveals that the giant exoplanet WASP-69b carries a comet-like tail made up of helium particles escaping from its gravitational field propelled by the ultraviolet radiation of its star.

Iron and titanium in the atmosphere of an exoplanet
Exoplanets can orbit close to their host star. When the host star is much hotter than our sun, then the exoplanet becomes as hot as a star.

Read More: Atmosphere News and Atmosphere Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to