I just gave the presentation "Smouldering mega-fires in the Earth system" at the conference Exploring the Mega-fire Reality, Florida State University. It went well very, good questions (~8) from audience and great feedback. The abstract is below.
Smouldering mega-fires in the Earth system
Smouldering fires, the slow, low-temperature,
flameless burning of organic matter release anually at a global scale
the equivalent to ~15% of man-made carbon emissions. It accounts for the
accidental burning of fossil fuels, including natural as well as
antropogenic causes. Very large fires of organic matter (mostly in
peatlands) have burnt since past millennia for long periods of time
(months, years, decades; the longest continuously fires on Earth).
Flaming forest fires have been the central focus of most research, but
smouldering mega-fires are paramount to the Earth System and have
received very little attention. Smouldering is the most persistent type
of combustion phenomena; the easiest to ignite, and the most difficult
to suppress. Peat fires propagate slowly (~1 mm/min) through organic
layers of the ground and can reach depth >5 m when large cracks
or a natural piping system exists. It is a 3-dimensional phenomena,
spreading deep into the soil and over extensive areas of land. The depth
of burn is given by the location of the inert layer, very moist layer
(>125%MC) or firefighting attempts. Observed depths of burn
reported in the literature range from 0.1 to 5 m, with the average
around 0.5 m (=75 kg/m2 of fuel consumption). This is 40 to 90 times
larger than flaming fires. In terms of fuel consumption, these are
mega-fires. This is of great concern given that world peatlands contain
more terrestrial carbon than the forests or the atmosphere. Compared to
the natural carbon flux to the atmospherefrom from peatland degradation,
smouldering fires is 3,000 times faster.
These wildfires burn fossil fuels and thus are a carbon-positive fire
phenomenon via soil moisture deficit and self-heating. Warmer
temperatures at high latitudes are resulting in more frequent Artic
fires and unprecedented permafrost thaw.