Fires like those burning for a week in France and Spain are so intense they often make direct firefighting impossible, marking a new pattern driven by climate change that calls for a tailored response.
The fires that broke out over the past week in France and Spain, which have already burned more than 115,000 hectares and forced more than 320,000 people from their homes, have stood out for the sheer ferocity and scale of the flames. The French authorities acknowledge that they may take months to put them out.
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They are the latest examples of what the operational and scientific community began calling, from the second half of the 2010s onwards, "sixth-generation fires", especially after the blazes in Pedrógão Grande in Portugal (2017) and in Greece (2018), each of which claimed more than 100 lives.
This new pattern first became more evident in Europe, although it was also detected in 2017 in Chile, where it reappeared, in even more devastating form, in 2024, a year in which 137 people lost their lives. The same features have also been observed elsewhere, notably in Australia (2019-20), on the west coast of the United States (2020) and in Canada (2023).
The major change in fire behaviour is being driven by climate change, explains Domingos Xavier Viegas to Euronews, a professor at the University of Coimbra's Faculty of Science and Technology (FCTUC) and a specialist in rural fires. With higher temperatures, less rainfall and lower humidity, the soil and vegetation become drier, which greatly increases the "conditions for ignition" and the "area available to burn".
What sets a sixth-generation fire apart?
The destructive potential of these megafires stems from the energy released, which can alter the weather conditions around them and overwhelm conventional firefighting methods, however robust they may be.
"When more than ten megawatts (MW) per metre are being released, the fire can no longer be extinguished through firefighters' direct action," Xavier Viegas explains. "If we translate this into flame length, a front releasing ten MW will have flames roughly ten metres high," he adds.
"What happens is that, nowadays, we sometimes have fires which, in some phases of their spread, reach intensities three, four, five, even six times higher. In other words, you cannot fight flames that reach up to 60 metres in length," the specialist notes.
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 form, carrying intense heat, changing the direction of the wind, producing electrical discharges and throwing embers several kilometres away, sparking new fires.
Out of season and in unusual locations
Sixth-generation fires are becoming more frequent and, in the words of the University of Coimbra expert, "are not a one-off summer event". 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 across an "ever wider geographical area", says Xavier Viegas. "In Portugal, these fires used to occur mainly in the north and centre and now, at times, they also appear on the coast and in the Alentejo, in regions where they were not common."
The same trend is evident across the rest of Europe, where fires are no longer confined to the south: in recent weeks, central and northern countries such as Germany, Switzerland and Norway have also been battling wildfires.
This is a "global phenomenon" that calls for an "integrated" approach, including when it comes to prevention. "Even tourists need to be aware of this," stresses Xavier Viegas, referring to the recent fire in Almería, in south-eastern Spain, which left 14 people dead, 12 of them foreign nationals. "They were not familiar with that reality," he underlines.
How do you fight these fires?
Ground crews and even the heaviest aircraft cease to be effective in stopping the head of a sixth-generation fire. To protect people, property and infrastructure, the FCTUC specialist therefore recommends attacking the fire from the rear or from the flanks.
"Areas of discontinuity" can be created by using "any natural feature that may exist, for example a river or a patch without vegetation".
Another strategy is to open up a strip of land by "cutting the vegetation using tracked machinery" or widening that strip "with the help of a backfire", something "only the authorities can do". This operation, however, is risky if the wind is blowing strongly, as has often been the case.
"Sometimes embers are projected beyond that barrier and, as it were, all the effort goes to waste," he stresses.
In such circumstances, Xavier Viegas warns, pragmatism is needed to avoid tragedies. "Generally speaking, people expect firefighters to put out any fire, wherever it is, and do not realise that there is a part of the fire that cannot be suppressed. We should not want firefighters to risk their lives, not least because it is a losing battle."
These fires are particularly devastating in forest environments because of combustible material such as "vegetation and woodland". When they reach more urban areas, "they no longer have the same spread characteristics, and homes and buildings can be safe places for people," he says.
Evacuating communities to built-up residential areas is therefore a solution to consider.
"There are certain houses and buildings which, even if they were hit by a fire of this intensity, could probably withstand it and serve as a shelter," he concludes.
