Charcoal reveals wildfire history

UK scientists have traced the history of wildfires by studying lumps of ancient charcoal from around the world.

The fossils show the incidence of fires through time is closely related to the level of atmospheric oxygen.

Andrew Scott and Ian Glasspool say huge swathes of the planet were ablaze when concentrations of the gas peaked some 275 million years ago.

Their research is published in the US scientific journal Proceedings of the National Academy of Sciences.

"People might think the charcoal they pull out of a bonfire is just rubbish; but look at it under a microscope and you see that it has beautiful anatomical preservation," said geologist Professor Scott, from Royal Holloway, University of London.

"In other words, the charcoal retains information not just about the fire but about the type of plants that were being burned. This means we can tell whether the fires moved through surface plants or big trees," he told BBC News.

Charcoal is almost pure carbon and is left virtually unchanged in the fossilisation process.

Scott and Glasspool, who is affiliated to Chicago's Field Museum, examined charcoal residues preserved from about 440 to roughly 250 million years ago.

It covers the period when scientists believe plants first got a strong foothold on land and spread rapidly across the surface.

The charcoal samples studied came from all around the world, including the US, Australia, Scotland, India, Norway, South Africa and Antarctica.

The researchers examined the material to ascertain the types of fires that produced the charcoal and their likely incidence. They then compared this with models other scientists have produced to describe how oxygen in Earth's atmosphere is thought to have changed over time.

The team found that fires were rare and localised for the first 50 million years of plant evolution but then they increased in frequency as the levels of oxygen in the atmosphere rose.

From around 365 million years ago, severe fires became widespread across the planet. Oxygen levels peaked at 30% 275 million years ago, in comparison with only 21% today. In this period even damp vegetation would have ignited easily causing many more fires.

"From the Late Devonian - from about 365 million years ago - there was a rapid increase in fire," Professor Scott explained.

"One might have expected that to occur earlier but it seems to have coincided with this rapid rise in atmospheric oxygen that people have modelled. So, this is the first time anyone has used the charcoal record to constrain the atmospheric oxygen models."

The Royal Holloway scientist has spent the best part of 30 years studying charcoal.

It is clear, he argues, that fires have been an integral part of the Earth system and that changing atmosphere and climate are both influenced by, as well as influencing, fire occurrence.

"Fire sustains certain systems. If more carbon is bound up and buried as charcoal, you are taking carbon dioxide out of the atmosphere, which changes the climate.

"In the time we looked at, we had the 'global ice house' (a period worldwide cooling) and a fall in sea levels; you have therefore more area to be colonized by plants which can burn. And as the oxygen levels rise, you can burn more and more of the wetter material. So, you get various feedbacks.

"From an Earth systems point of view, factoring in fire is quite important. Too many geologists in the field dismiss charcoal as detrital plant material and throw it away.

"As people recognise the information content of charcoal and its significance, hopefully more people will collect it."

I spent last week at the World Congress of Soil Scientists meeting in Philadelphia. In one of the Soil Micromorphology sessions, we were treated to a remarkable presentation by a French scientist named Marie-Agnes Courty. She has spent about 20 years looking at shocked quartz (and other shocked minerals) and charcoal in soils around the Mediterranean. Her work strongly supports that of Mike Baillie (of Exodus to Arthur fame); she finds a soil layer dating to approximately 2350BC that is full of evidence of meteorite impact and resultant wildfires. She has identified an impact site on the edge of Antarctica just south of South Africa, but from the scatter of shocked minerals, it is apparent that there was also an impact site somewhere in the Mediterranean area.

She has also studied minerals and charcoal from Mousterian culture sites in Spain. Her findings from this study astounded me. Working in sites that showed more-or-less continuous habitation by Neanderthals, she found that charcoal deposits in caves (from hearths) were sporadic, and occurred only during times where there was evidence of forest fire in the surrounding open areas. From this, she infers that Neanderthals WERE NOT ABLE TO MAKE FIRE, BUT COULD ONLY COLLECT IT WHEN IT OCCURRED NATURALLY. If her assumption is correct, it would go a long way in explaining why Neanderthals were outcompeted by modern humans!!

That's just more grasping at straws, Neandertal wasn't outcompeted:

The Neandertal Enigma
by James Shreeve
Frayer's own reading of the record reveals a number of overlooked traits that clearly and specifically link the Neandertals to the Cro-Magnons. One such trait is the shape of the opening of the nerve canal in the lower jaw, a spot where dentists often give a pain-blocking injection. In many Neandertal, the upper portion of the opening is covered by a broad bony ridge, a curious feature also carried by a significant number of Cro-Magnons. But none of the alleged 'ancestors of us all' fossils from Africa have it, and it is extremely rare in modern people outside Europe." [pp 126-127]

Courty (in the paper below, from circa 1997) winds up refuting a volcanic origin for the evidence, and prematurely dismisses a catastrophic cause for the "Curse of Agade". Just a few years later an impact crater was found...

Causes And Effects Of The
2350 BC Middle East Anomaly
Evidenced By Micro-debris Fallout,
Surface Combustion And Soil Explosion
by Marie-Agnès Courty
circa 1997
Occurrence in a previously recorded thick tephra deposit of particles identical to some of the mysterious layer and resemblance of its original pseudo-sand fabric with the exploded one of the mysterious layer confirms that the later is contemporaneous with the tephra deposit It has been however impossible to find typical tephra shards in sites located at a few km around the one with the tephra deposit The restricted occurrence of the later suggests that the massive tephra accumulation can no longer be considered as a typical fallout derived from the dispersion of material from a terrestrial volcanic explosion.
Meteor clue to end of Middle East civilisations
by Robert Matthews, Science Correspondent
2001
"Studies of satellite images of southern Iraq have revealed a two-mile-wide circular depression which scientists say bears all the hallmarks of an impact crater. If confirmed, it would point to the Middle East being struck by a meteor with the violence equivalent to hundreds of nuclear bombs. The catastrophic effect of these could explain the mystery of why so many early cultures went into sudden decline around 2300 BC. They include the demise of the Akkad culture of central Iraq, with its mysterious semi-mythological emperor Sargon; the end of the fifth dynasty of Egypt's Old Kingdom, following the building of the Great Pyramids and the sudden disappearance of hundreds of early settlements in the Holy Land."
Comets, Meteors and Myth: New Evidence for Toppled Civilizations and Biblical Tales
by Robert Roy Britt
13 November 2001
Biblical stories, apocalyptic visions, ancient art and scientific data all seem to intersect at around 2350 B.C., when one or more catastrophic events wiped out several advanced societies in Europe, Asia and Africa. Increasingly, some scientists suspect comets and their associated meteor storms were the cause. History and culture provide clues: Icons and myths surrounding the alleged cataclysms persist in cults and religions today and even fuel terrorism. And a newly found 2-mile-wide crater in Iraq, spotted serendipitously in a perusal of satellite images, could provide a smoking gun. The crater's discovery, which was announced in a recent issue of the journal Meteoritics & Planetary Science, is a preliminary finding. Scientists stress that a ground expedition is needed to determine if the landform was actually carved out by an impact... Archeological findings show that in the space of a few centuries, many of the first sophisticated civilizations disappeared. The Old Kingdom in Egypt fell into ruin. The Akkadian culture of Iraq, thought to be the world's first empire, collapsed. The settlements of ancient Israel, gone. Mesopotamia, Earth's original breadbasket, dust.

Shouldn't that be "toast"? ;')

"Her work strongly supports that of Mike Baillie (of Exodus to Arthur fame); she finds a soil layer dating to approximately 2350BC that is full of evidence of meteorite impact and resultant wildfires. She has identified an impact site on the edge of Antarctica just south of South Africa, but from the scatter of shocked minerals, it is apparent that there was also an impact site somewhere in the Mediterranean area."

Excellent book and has influenced my thinking.

"From this, she infers that Neanderthals WERE NOT ABLE TO MAKE FIRE, BUT COULD ONLY COLLECT IT WHEN IT OCCURRED NATURALLY. If her assumption is correct, it would go a long way in explaining why Neanderthals were outcompeted by modern humans!!"

I would also consider that they showed up to scavenge the animals killed in the fire.

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