Are wildfires so difficult to put out? Should we just let them burn?

In early January 2025, another wildfire began to spread from southern California, USA . As of the early morning of January 16 local time, the wildfire had killed more than 25 people, destroyed more than 12,000 buildings, and scorched more than 60 square miles of land.

Just a few days ago, wildfires broke out in Heshan City and Zhaoqing City, Jiangmen City, Guangdong Province. Local authorities organized rescue forces from all sides to rush to the scene to put out the fires. Fortunately, according to CCTV and Xinhua News Agency, the fires have been extinguished and there are no reports of casualties.

At this time, the cause of both fires remains unknown.

Fire from the sky

China's almost strict mountain closure and fire ban management has greatly reduced the number of forest fires caused by human factors in recent years .

However, we can control the burning of paper in worshipping mountains, children's fireworks and firecrackers, cigarette butts thrown away casually, and sweet potatoes and roasted chickens roasted to a crisp among dead branches and dry firewood, but we cannot avoid natural disasters . For example, the major forest fire in Daliang Mountain in early spring 2019 was caused by a "thunderbolt" caused by an adult Yunnan pine about 20 meters tall in the primeval forest: the dry trunk was struck by lightning and caught fire, and the fire spread down and ignited the scattered and dry dead branches and leaves on the ground; in early spring, there was a long drought and no rain, and the mountain wind was as sharp as a knife. Then the fire took advantage of the wind, and the wind helped the fire, and naturally swept the entire forest.

A real lightning-struck tree | Geo Lightspeed7 / wiki commons

Lightning fires are not uncommon. In the Daxing'anling virgin forest in northeast China, "lightning" is the main cause of forest fires. In front of the earth, which is revered by humans as "mother", we and the ecosystem we work hard to maintain are equally vulnerable.

You may have received similar text messages before | Photo provided by the author

I believe everyone has received a text message of a red alert for forest fires. In fact, fires caused by drought are predictable. For California, although wildfires are not uncommon and there are reports of wildfires almost every year , fires themselves are also part of the self-renewal of the local ecosystem; but everything is excessive, and this year's overly fierce wildfires are still shocking. Although the possibility of arson cannot be ruled out, the strong and dry Santa Ana winds and the driest winter on record caused by months of no rain are important factors that contributed to this year's wildfires - in the final analysis, this wildfire also stems from the inevitable but ongoing climate change .

News coverage of the Camp Fire in California in 2018 | BBC

Invisible fire is the most deadly

How terrible are forest fires? People who have seen them probably don’t want to talk about them anymore.

Unlike urban fires, forest fires cannot be extinguished with water , carbon dioxide or foam fire extinguishers. The "fuse" of a lightning fire is usually the tallest, dry tree in a forest. The flames go down along the old tree trunks and ignite the dry grass and dead branches and leaves under the forest.

The forest fire will then split into two routes. The one that goes up is called a crown fire , which mostly starts to burn along the canopy of coniferous trees; the one that goes down is called a surface fire , which spreads from the surface and burns the ground cover.

Why is there no mid-lane mage? Because the forest fire itself is like the embodiment of some kind of terrifying magic.

Diagram of crown fire, surface fire and underground fire | wfca

94% of forest fires are surface fires, which can be roughly divided into two categories: rapid surface fires that drift forward with the help of the wind and cause less damage; and steady surface fires that move slowly, burn for a long time at high temperatures and high intensity. Because surface fires are short, most of them can be extinguished or put out. If you are lucky, they may be blown out directly by the wind.

Two types of surface fire | Famartin / wiki commons, climatecheck

Crown fires only account for 5% of forest fires, and they are mainly caused by surface fires that "fly up the branches" under the action of strong convection. Crown fires are high in height, temperature, and smoke column . Wherever they pass, there is thick smoke and the eyes cannot see anything, making them extremely difficult to extinguish.

Crown Fire | csfs.colostate.edu

Under the surface fire, there is another kind of fire that will devour life silently - underground fire . Underground fire accounts for only 1% of forest fires. It usually occurs in the dry winter and burns in the humus layer or peat layer. The flames cannot be seen on the surface, only the smoke can be seen. It spreads very slowly and lasts for a very long time . It can burn all the peat, humus and tree roots in the soil, and can even burn all the way to the mineral layer or groundwater layer.

Underground fires are difficult to detect and put out. By the next spring, the dense forest that seemed unchanged is already a dead tree .

Effects of underground fire on tree roots and soil | Adam C. Watts & Leda N. Kobziar / Fire Ecology volume 9, pages 124–132 (2013)

Strict fire prevention is the right way

For a long time, and in most parts of the world today, forest fire prevention relies on watchtowers. Friends who live in forest areas must have seen a trembling, shaky, about 20-meter-high iron tower suddenly appearing in the lush forest.

Yes, that's the watchtower .

A fire lookout tower in Minnesota | Bubba73 (Jud McCranie) / wiki commons

Forest rangers regularly climb up the towers to observe the fire situation and the spread of forest fires in a 360-degree all-round and all-round manner. As long as the number and location of the towers are set reasonably, a small number of towers can fully monitor the forest area .

Even so, it is neither easy nor simple to rush to the watchtower in the deep mountains and forests and watch hard against the cold wind. In addition, communication is difficult in most forest areas, and even if dangerous situations are discovered in time, it is difficult to rush to extinguish the fire in the first place.

Currently, the more advanced and mainstream method is to conduct real-time monitoring through aircraft and satellites , use remote sensing technology to accurately locate the fire point, establish a fire prediction model, and quickly and accurately dispatch fire-fighting personnel and equipment.

Map app to track wildfire conditions | frontlinewildfire

Put out the fire early

Since China has many mountainous areas and vast forest areas, fire prevention and forest protection often rely on local people, so "preventing problems before they happen" is the key to fire prevention. Forests prone to fire have several things in common: coniferous forests with low water content and high oil content, dry climate, and lack of water nearby .

In order to avoid fires and to prevent the fire caused by the thunder from becoming a major problem, mature forest areas will plant broad -leaved trees with high water content in the middle of the coniferous forests. For example, in the south, fire-resistant tree species such as Schima superba, Castanopsis sclerophylla, Cyclobalanopsis glauca and Michelia odorifera are planted, while in the north, there are the famous three "hard broad-leaved" trees of the Northeast - Fraxinus mandshurica, Phellodendron amurense and Juglans mandshurica.

In order, they are Fraxinus mandshurica, Phellodendron chinense and Juglans mandshurica | Krzysztof Ziarnek, Kenraiz, / wiki commons

The principles for fighting forest fires are also very simple and crude: " fight early, fight small, and fight thoroughly ." "Early" means to act in advance and quickly; "small" means to grasp the core and seize the opportunity; "sufficiently" means to "kill all" to prevent re-ignition.

If "beating" cannot solve the problem, it means that conventional methods are useless. Why not use high-pressure water guns? First, high-pressure water guns cannot reach high mountains or deep forests. Second, once the fire is too big, water will have no dignity in front of the fire. The sprayed water will evaporate into water vapor a few meters away and may not even be able to cool down the fire. So we said before that forest fires cannot be extinguished with water. Moreover, instead of wasting water and effort, it is better to directly create artificial rainfall.

So why don't we use seawater to put out fires in coastal areas like California? The most important reason is that seawater may corrode firefighting equipment and damage the ecosystem . If seawater is used to put out fires, the water in the seawater will evaporate quickly, leaving a large amount of salt that will clog and corrode firefighting equipment, affecting subsequent rescue operations. At the same time, a large amount of salt may cause the vegetation, small animals and microorganisms in the community to die due to dehydration, and may even affect the local soil structure.

If it really comes to the point where seawater is needed to put out the fire, it must be an extremely bad situation.

Experiments on the effects of salt water on soil | Alice Stearns/Smithsonian Environmental Research Center

The core temperature of a wildfire can reach 2000℃ , and the raging fire that reaches the sky is like a special effect in a movie. Even a savvy Homo sapiens cannot confront a burning forest head-on.

So we chose to dig a ditch .

Yes, cutting down trees, digging trenches, burning isolation belts, no matter which method is used, the fire area is limited. When there is nothing to burn, the fire will stop naturally. At this time, even if there are sporadic fires flying out of the isolation belt or re-igniting, it is within the controllable range.

Comparison of the two sides of the isolation belt after a forest fire | Ryanj93 / wiki commons

This kind of method is undoubtedly the helpless act of tiny human beings in the face of natural disasters. The ancients once laughed at ants trying to shake trees and mantises trying to stop chariots, but when faced with a raging fire, we are no different from the insects we once laughed at.

I hope our earth will get better and better.

Author & Editor: 媗媗

Title image source: Los Angeles Times

This article comes from GuokrNature (ID: GuokrNature)

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