May 2024 was the warmest May on record, according to data from the Copernicus Climate Change Service. In Greece, the wildfire season has already started. What do NILU’s forest fire experts expect the summer will bring for Europe – and Norway?
Last year’s summer was the warmest registered so far, with record temperatures, flooding and wildfires in abundance. With climate change leading to warmer temperatures and drier conditions, the fire season is starting earlier and ending later.
Southeastern Europe at risk, rain in Norway
“According to the seasonal forecast from EFFIS, the Balkans, Greece, and southern France will likely have a hot summer with relatively little precipitation. Based on that, I’d say there is an increased risk of forest fires in what we could call the ‘classical areas’ of southeastern Europe and France,” says Dr Johannes Kaiser from NILU’s department of Atmosphere and Climate.
EFFIS is the European Forest Fire Information System, with experts working to develop and implement methods to evaluate forest fire danger, map burnt areas and give recommendations for improved forest fire prevention in the European and Mediterranean regions. Since 2015, EFFIS has been part of the EU Copernicus Program.
The same forecast shows that Scandinavia will have quite a bit of rain.
“That is bad news for those planning to spend the summer in Norway, but it means the risk for forest fires is much smaller here,” says Kaiser’s colleague, senior scientist Dr Nikolaos Evangeliou.
Drought and dead forests
As the global temperature rises, it also affects the earth’s water cycle. A warmer climate causes more water to evaporate. A warmer atmosphere is also able to hold more water, which means that we get more rainfall and stormwater. Such changes cause wet areas to become wetter, and dry areas to become drier.
More drought makes forests die – and burn more easily. The low humidity also leads to increased fire risk in areas with a lot of litter, what the scientists refer to as “biomass/fuel availability”.
“In several countries in Europe, there are large boreal forests where no biomass removal or maintenance have ever been done. That creates a very dense tree population. If you don’t remove deadwood and litter, and add drought into the equation, such regions can become more vulnerable to fires over time,” Evangeliou explains.
Prevention measures
To prevent forest fires, removal of the biomass is key. In some areas, people do so-called prescribed burning. They set the forest on fire in a controlled manner, in order to reduce the amount of fuel on the ground. If a fire should start, it doesn’t spread so quickly, it doesn’t get so intense, and it’s easier to tackle.
Another means of preventing or delaying the spread of forest fires is so-called firebreaks. These are wide stretches of cleared or plowed land, preventing the fire from jumping from one place to another. This practice is fairly common in both Greece and Germany, where the two scientists originally hail from.
“My family’s country house in Greece has burned down twice in wildfires, in 1992 and 1996. Since 1996, the authorities have been cleaning the litter every single year, and we have not had any problems since. That shows that it is possible to reduce the risk of forest fire with relatively simple means, as long as money is set aside for it,” says Evangeliou.
Wildfire risk factors
Not all regions burn alike. Several factors must be taken into consideration when talking about wildfire risks. Certain types of trees, for instance, burn better than others.
Pine trees burn well, and they’re abundant in areas known for big forest fires – like Greece and Southern France between Bordeaux and the Atlantic. Portugal has large plantations of eucalyptus, to provide raw material for paper and paper pulp industry. This species also burns easily, according to Dr Johannes Kaiser.
“Both pine and eucalyptus contain a lot of oil, and the eucalyptus leaves and bark are also very flammable. When burning strips of eucalyptus bark tear off the trunks, they can be carried by the wind and spread the flames even further. In addition, eucalyptus also use a lot of water, so they dry out the ground,” he says.
Does it matter if it burns?
When scientist assess forest fire risks, many factors come into play. Meteorology is one thing – how much available fuel there is, another. Then comes vulnerability.
“When talking about how much damage a fire does, we’re really talking about what assets there are, and if it matters if it burns or not. Are people threatened? Will anything of economic value be destroyed? When wildfires reach populated areas, both people and property are endangered,” says Kaiser.
Different areas can vary a lot regarding how vulnerable they are. Scientists also differ between ecological vulnerability and economic vulnerability.
In the EFFIS fire risk viewer, Evangeliou uses the Nordic countries as an example. When choosing to show ‘economic vulnerability’, the Nordics are at the low end of the scale.
“The tool takes into consideration vegetation restoration cost for forest and agricultural areas, and here in the north there are very large areas with little agricultural activity compared to the rest of Europe,” he says.
On the other hand, when he chooses to look at ‘ecological vulnerability’, the map shows Norway, Sweden and Finland as very vulnerable.
This is due to the huge forests, and the fact that if you burn a Norwegian fir-covered landscape, it takes several hundred years until it recovers. In contrast, if mediterranean shrubland burns, it’s back to normal only a few years later.
Climate change and wildfire: A closed loop
The relation between climate change and more frequent forest fires is a closed feedback loop. Very simply put, you start with the extreme temperatures we have now, which contribute to dried-out forests, leading to a larger number of fires. These fires release particles and pollutants into the atmosphere, where they are transported, some of it towards the Arctic. The particles deposit on snow and ice, darkening the surface and reducing the albedo – the ability to reflect heat. Thus, the ice sheets melt faster, which again contributes to climate change, which leads to even warmer temperatures – and so on.
In reality, it is much more complicated. Smoke from fires can for instance also contribute to cooling the atmosphere. Also, increased melting of large ice sheets lower salinity in parts of the ocean. This has the potential of affecting ocean currents, which again may change the global distribution of heat and weather patterns. Less ice can also expose more permafrost, which may lead to higher emissions of methane, which means more global warming and more fires.
An added worry is the extreme wildfires, who are large enough and hot enough to upset the ecological system. When the natural cycle is disturbed, you’re running a risk of it contributing to change in the ecosystem and the land cover.
“It’s natural for boreal forests like we have here in Scandinavia, Russia and Canada to burn. In their natural state they’ve got a repeat period of a few hundred years – let’s say that a given piece of forest burns down every 300 years. If the wildfires get more frequent, maybe every 30 years instead, the forest doesn’t have time to grow back and recover completely to its original state. The fires accelerate the change of the land cover as the forests burn down, which means less carbon uptake, thus more climate change,” says Kaiser.
Time will show how the European forest fire season of 2024 turns out. What is certain is that human, ecologic and economic costs from wildfires only can be reduced if adequate emergency prevention, response and recovery measures are implemented in a sustainable and regionally adapted manner.
