The way forest fires spread is changing. Rural depopulation, climate change, droughts and even the nature of fires has led to sixth-generation wildfires.
Did you know that more than seven million hectares set on fire during the past year in Australia? These are the most destructive fires that the country has experienced ever, and some scientific researches had guessed it a few years ago.
What is a sixth generation wildfires?
This term became more popular about three years ago, when the north of Chile was devastated by the enormous voracity of wild fires. What makes these fires peculiar is a consequence of the interaction of climatic and atmospheric conditions. The emission of a large volume of heat generates air streams that feed back to the flames and multiply their effects.
Examples of sixth generation wildfires
The frequency of sixth generation fires is increasing lately. Added to the catastrophe in Chile was the tragedy of Pedrógão Grande in Portugal. Sadly, sixty people were burned in a few seconds by an igneous storm.
In Spain we also had very hard times, both in Gran Canaria and in Tarragona, where the extinguishing teams had to fight fiercely against the fire. Additionally, Greece and California also had to contend with sixth-generation wildfires of similar characteristics in 2018.
Spread of sixth generation wildfires
One of the main characteristics of sixth generation forest fires is how quick they are when spreading. In just six hours, the fire that broke out in Tarragona had devastated around 2,000 hectares in 2019.
This devastating phenomenon is due to large air streams. Having so much combustible material (trees, vegetation, high temperatures, winds, weeds …), large amounts of energy are released. This is how huge columns of hot air rise into the atmosphere, and re-feed the flames from the surface.
Forest fire fighting crews were familiar with “pyrocumulus”. However, in recent years they have had to face the “pyrocumulonimbus”, which are walls over ten kilometers high capable of reaching the troposphere. We can call them “huge firestorms” that reach a size against which it is impossible to fight.
When these types of fires happen, the reaction must be very fast and unanimous, both on the part of the authorities and the extinguishing teams.