The wildfires that broke out last week in France and Spain, which have already burned more than 115,000 hectares and displaced more than 320,000 people, have stood out for the sheer violence and scale of the flames. The French authorities admit that it could take months to extinguish them.
They are the latest examples of what the operational and scientific community has, since the second half of the 2010s, come to describe as "sixth-generation wildfires", especially after the fires in Pedrógão Grande in Portugal (2017) and in Greece (2018), each of which caused more than 100 deaths.
This new pattern first became more evident in Europe, although it was also detected in 2017 in Chile, where it returned in an even more devastating form in 2024, a year in which 137 people lost their lives. These characteristics have also been observed in other latitudes, notably in Australia (2019-20), on the west coast of the United States (2020) and in Canada (2023).
The major shift in fire behaviour is driven by climate change, explains Domingos Xavier Viegas to Euronews, a professor at the Faculty of Science and Technology at the University of Coimbra (FCTUC) and an expert in rural fires. With higher temperatures, less rainfall and lower humidity levels, the soil and vegetation become drier, which greatly increases the "conditions for ignition" and the "area available to burn".
What sets a sixth-generation wildfire apart?
The destructive potential of these mega-fires stems from the energy they release, powerful enough to alter the weather conditions around them and to exhaust traditional firefighting methods, however robust they may be.
When more than ten megawatts (MW) per metre are released, the fire can no longer be extinguished through firefighters' direct action, Xavier Viegas clarifies. "If we translate this into flame length, a front that releases ten MW has flames roughly ten metres high," he adds.
"What happens is that, nowadays, we sometimes see fires which, in certain phases of their spread, reach intensities three, four, five, even six times higher. In other words, it is not possible to fight flames that can reach up to 60 metres in length," the specialist observes.
A thermal load of this magnitude means that this type of fire feeds itself, ceasing to be just a phenomenon controlled by the local atmosphere and starting to influence it as well.
Exceptionally dense smoke clouds are generated that carry intense heat, change wind direction, produce electrical discharges and hurl embers several kilometres away, triggering new ignitions.
Out of season and in unusual regions
Sixth-generation wildfires are becoming increasingly frequent and, in the words of the University of Coimbra expert, "they are not an isolated event in summer". Take the case of Pedrógão Grande nine years ago, where the flames first broke out in June, still in spring, and later in October, already in autumn.
In addition, they occur over an "ever larger geographical area", notes Xavier Viegas. "In Portugal, these fires used to occur in the north and centre, and now, at times, they also appear on the coast and in the Alentejo, in regions where they were less common."
The same trend is seen in the rest of Europe, where the flames are no longer confined to the south: in recent weeks, central and northern countries such as Germany, Switzerland and Norway have been grappling with fires.
This is a "global phenomenon" that demands an "integrated" approach, including in terms of prevention. "Even tourists need to be aware of this," stresses Xavier Viegas, referring to the recent wildfire in Almería, in south-east Spain, which led to the deaths of 14 people, 12 of them non-Spanish citizens. "They were not familiar with that reality," he underlines.
How can these fires be fought?
Ground resources and even the heaviest aircraft cease to be effective in halting the front of a sixth-generation wildfire. To protect people, property and infrastructure, the FCTUC specialist therefore recommends attacking the fire from the rear or from the flanks.
Areas of "discontinuity", or firebreaks, can be created, making use of any natural feature that may be present, for example a river or a zone without vegetation.
Another strategy is to open up a strip of land by "cutting the vegetation with tracked machinery" or to widen that strip "with the help of a backburn", something that "only the authorities can do". This operation is, however, risky if the wind is blowing strongly, as has so often been the case.
"Sometimes, an ember is projected beyond that barrier and, so to speak, all the effort goes down the drain," he emphasises.
In such circumstances, warns Xavier Viegas, pragmatism is needed to avoid tragedies. "Generally speaking, people expect firefighters to put out any fire, wherever it may be, and do not realise that there is a part of the fire that cannot be suppressed. We should not wish firefighters to risk their lives, not least because it is a hopeless struggle."
These fires are particularly devastating in forest environments because of fuels such as "vegetation and woodland". When they reach more urban areas, "they no longer have the same patterns of spread, and at that point houses and buildings can be safe places for people," he states.
Evacuating people to built-up residential areas is therefore a solution to consider.
"There are certain houses and buildings which, even if they were impacted by a fire of this intensity, could possibly withstand it and provide shelter," he concludes.
This text was translated with the help of artificial intelligence. Report a problem : [feedback-articles-en@euronews.com].
