300,000-year wildfires - 'Hellish' fires burned through Europe after supercontinent Pangea broke up

Scientists have discovered that a fire kept burning in Europe for between 40,000 and 300,000 years following the end-Triassic mass extinction nearly 201 million years ago. As supercontinent Pangea began to break apart, volcanoes erupted, primarily from the Central Atlantic Magmatic Province (CAMP). This event wiped out approximately 76 per cent of all terrestrial and marine species. Huge quantities of carbon dioxide were released into the atmosphere as temperatures climbed by an estimated 5 to 10 degrees Celsius worldwide.

Forests collapsed, and Northwest Europe was soon covered by ferns. An international team of scientists led by geologists at Utrecht University have suggested that the ferns were vulnerable to fire, which triggered the spread of massive wildfires. The study in the journal Nature Geoscience states that the ferns also provided the fuel in many cases, which further fuelled the wildfires.

The team drilled four cores of sediments, one of which came from a depth of nearly 2,100 feet.

They measured fossil charcoal and organic compounds produced in wildfire smoke called polycyclic aromatic hydrocarbons (PAHs) to recreate the ancient wildfires. They found that during the main extinction interval, massive fires burnt in the region. This period coincided with the rapid spread of ferns.

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Testing the sediment

However, charcoal can break down into fragments and smoke-related molecules can travel far from the fires, exaggerating the intensity of the fires. So the team "used a simple and very low-cost technique that quantifies the ‘darkness’ of fossil pollen and spores, a so-called Palynomorph Darkness Index."

Samples gathered from the deepest points, which were also the oldest, had light colored pollen and spores. The extinction interval fossils became progressively darker and became extremely dark brown. After the extinction interval ended, they turned a light yellow colour. When the unusual darkening was compared with other indicators of ancient fires, they found a pattern, leading them to conclude that intense wildfire activity occurred along with fern abundance during the "Dark Zone".

Some fern species can grow back quickly, especially after a fire. Even after the leaves above the ground burn up, roots remain, which allows the plant to cover the burned areas again. Since the fern kept bouncing back, the fires persisted. The researchers estimate that they could have burnt for 40,000 years and for as long as 300,000 years.

Some fern species form savannahs across the landscape. "When the ferns dry out, the thick mats act as the ideal fuel to trigger massive wildfires," senior author Dr Bas van de Schootbrugge said. "Ferns responded to and delivered the fuel that fanned the flames, triggering repeated massive wildfires. A truly hellish world."

Van de Schootbrugge said that the study shows that climate change, deforestation, and certain species can once again set the stage for a new storm.