RFI EXPLAINS

Five questions about mega-fires

Strong winds and hot, dry weather thwart the efforts of French firefighters to contain a huge forest fire near Landiras, in southwestern France, on July 16, 2022. © Gironde firefighters communication service (SDIS 33) via PA

Text by: Nenad Tomic

7 mins

Since the beginning of the 21st century, mega-fires have become more frequent all over the world, raising many questions.

There is no very precise scientific definition of this phenomenon.

These are large-scale and intense forest fires, uncontrollable and ravaging areas of several thousand hectares.

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Why talk about mega-fires?   

“It is above all a question of the area burned and the duration of the fires”, explained, recently, Jean Jouzel, climatologist and former vice-president of the IPCC, on the TV5 channel.

No exact delimitation of the area of ​​the fires exists to be able to use the term.

In Europe, this term is used for forest fires over 1000 ha.

But in the United States or Australia, we speak of mega-fires when the area burned exceeds 10,000 ha.

Consequently, it is necessary to relativize this notion which largely depends on the extent of the country or the continent.

The scale and intensity of the fire, the material or human damage caused as well as the duration over time, can take on considerable proportions, exceeding the capacities of the firefighters to fight the fire despite the means at their disposal.  

In France, the Senate published a report in September 2019, according to which we can speak of mega-fires “ 

 ”.

But on the ground, a fire of more than 5000 ha, in France, can be considered a mega-fire.    

The history of great forest fires  

From August 19 to 25, 1949, the Landes de Gascogne forest massif was plagued by a gigantic forest fire.

In six days, the fire ravaged 52,000 hectares, including 25,000 of wood.

The human toll is heavy: 82 victims in all the municipalities affected (Cestas, Saucats, Marcheprime and Mios, in the Gironde department).  

Mega-fires have occurred in many regions of the world and in particular in Amazonia, California, Australia, Russia (Siberia), the Mediterranean basin (Greece, Turkey, Spain, Portugal and France) and Africa , in the Congo Basin.

In recent years, under scorching temperatures in Siberia, forest fires have been almost constant, very destructive: more than 16 million hectares of wood have gone up in smoke.  

In summer 2018, Greece was hit by one of the deadliest fires in Europe: forest fires killed 102 people.

Almost at the same time, the forests caught fire in Latvia and Sweden and the vegetation was destroyed up to the polar circle.   

A few months later, in November 2018, the monster fire in California burned everything on 60,000 hectares and killed 85 people.

In the same region, two other mega-fires broke out in August 2020 and ravaged more than 140,000 hectares of forest.  

At the end of 2019, mega-fires are destroying forests in Siberia, Brazil, Congo and again in California.

During the same period, in Australia, bushfires started quickly becoming uncontrollable.

For several months, these mega-fires will ravage everything over approximately 6000 km² while the smoke released will invade even large urban centers such as Sydney, Canberra or Melbourne.   

Moreover, France has been plagued by large fires since 2021 in two main regions: the south-east and the south-west.

In 2021, a very large forest fire ravaged more than 7500 ha in the Var.

And in July 2022, in Gironde, the mega-fire started from two towns south of Bordeaux: La Teste de Buch and Landiras.

More than 20,000 hectares of pines are destroyed and several tens of thousands of people evacuated from the affected area.

At the same time, the fires are affecting Greece, Portugal and southern Spain.

The causes and origins of mega-fires  

Mega-fires are most often of human origin: criminal or accidental.

But their development and intensity is very often caused by high temperatures over a long period, drought and lack of rainfall as well as the state of maintenance of the forests.   

Logging operations, including pine plantations as is the case in the Landes or Gironde, are particularly flammable and contribute to the spread of the fire.

Furthermore, the large expanse of these forest massifs, with no breaks between plots, plays on the rapid spread of fire.

This phenomenon can also be observed in Spain and Portugal, or even in Sweden, which has around 70% of very compact industrial forest.  

In addition, forest maintenance and brush clearing is singled out as one of the causes of more frequent cases of mega-fires.

Individuals and sometimes even municipalities do not carry out the necessary work that will free the undergrowth of dead plants and elements that promote the spread of fire.

Improved forest management such as protection against flooding is essential in the fight against mega-fires which are the cause of human activity in 90% of cases.   

Is climate change responsible for the multiplication of mega-fires?  

Undoubtedly, climate change is a major contributor to the more frequent occurrence of devastating fires.

Because all natural environments (forests, steppes, savannahs or grasslands) are affected by the consequences of global warming.

Less rainfall and lower humidity, more frequent and longer periods of drought, and high temperatures offer more chances of a fire starting.  

Consequently, a veritable vicious circle is set in motion: the gigantic quantities of CO2 produced and released into the atmosphere during the fires in turn contribute to the aggravation of the global warming phenomenon.

Then, the reduction in the quantities of trees after the fire also lowers the capacity to absorb the quantities of CO2 in the atmosphere responsible for climate change.

Thus, forest fires will, over time, become even larger and more intense.   

According to the CNRS, the current conditions of global warming with more frequent episodes of drought and heat waves are more favorable to mega-fires compared to the climatic standards established during the pre-industrial era.

For example, fires in Australia are nine times more likely in the current climate than in a typical early 20th century climate.   

What are the consequences of mega-fires for nature and man?  

Currently, the average area destroyed by fire each year in Europe is on average 500,000 hectares, mainly in southern European countries.   

Thus, biodiversity seems to be the first to be affected by major forest fires.

Wildlife is moved from their habitat and must find another living environment.

Very often, certain species cannot survive and their disappearance is almost inevitable.

The destruction of forests by fires also puts the whole ecosystem to the test.

Several decades are needed for the flora and fauna to regain balance.  

Then, fires play on the reduction of air quality, because large quantities of fine particles are released into the atmosphere.

These fine particles, as during a peak of pollution in urban areas due to car traffic, are considered by the World Health Organization (WHO) to be carcinogenic.

In Australia, after the fires of 2019 and 2020, there is a higher number of lung cancers and other respiratory diseases among the population who have been exposed to smoke from the fires.   

Finally, the economic consequences are considerable.

Apart from the forest industry sector, major forest fires also affect homes, transport, the tourism sector (Gironde, Landes, Var, Bouches-du-Rhône, etc.) where several campsites are wiped off the map.   

Unfortunately, according to scientists, it is to be expected that this type of forest fire will increase in the future.

With the only weapon: prevention and preparation.

Our selection on the subject:

• To read :

→ Fires in Gironde: "The vegetation is ready to ignite with any spark"

→ Why is the forest burning?

→ How to live with tropical forests?

→ Tropical forests: a legacy of biodiversity

• To listen :

→ The United Nations warns of the increase in “mega-fires”

→ Western Europe overwhelmed by the heat wave and the forest fires

→ Canada: several hundred forest fires ravage western Canada

→ A wave of devastating fires hit southern Europe

→ In 2020, giant forest fires are ravaging the planet more than ever

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• Environment