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Understanding Wildfires: How Do They Start and What Causes Them?

In this article


-- Wildfire damage

-- Are wildfires getting worse?

How Do Wildfires Start Naturally?

Where Do Wildfires Occur?

How Do Humans Cause Wildfires?


how do wildfires start?


Wildfires are a huge environmental, societal and economic problem that is set to get worse. Every year, tens of thousands of forest fires burn across the globe, devastating vast areas of land as well as habitats and infrastructure, causing untold misery to surrounding communities.

Previous blogs have looked at recent wildfire trends and have delved into what exactly makes something a wildfire. This article will look more closely at how wildfires start: what causes them in the first place? It will seek to answer a variety of forest fire-related questions. How are wildfires caused? What starts wildfires? Why do wildfires start? What causes forest fires? Hopefully, by the end of this article, the answers to these questions regarding wildfire causes will be apparent.

For the purposes of this article, we will focus on unplanned, out-of-control wildfires, rather than controlled fires that serve an important ecological function.

Research shows that in the United States, up to 84 percent of wildfires are caused by people. Since human-caused fires spread faster, burn hotter and destroy more trees than ones caused by natural phenomena, efforts to prevent them should be of paramount importance.

Wildfire Damage

This damage is wide ranging: billions of tonnes of CO2 being emitted, billions of animals perishing and hundreds of billions of financial losses being incurred. And this is before we even start taking into account the respiratory issues and health complications that wildfires cause.

To uncover the often overlooked consequences of forest fires and explore effective solutions to mitigate their devastating impact, we invite you to download our comprehensive whitepaper, 'What Lies Beneath: the hidden truth about wildfire.'

This in-depth paper delves into the far-reaching effects of forest fires, exposing the detrimental consequences on our environment, the loss of precious lives, the profound impact on wildlife, and the staggering economic costs incurred. Moreover, it sheds light on the latest technological advancements that are playing a pivotal role in combating these fires and safeguarding our communities and natural resources.

'What Lies Beneath: the hidden truth about wildfire.'

Are wildfires getting worse?

Unfortunately, the evidence points to a conclusive yes.

The number of wildfires, the amount of land they burn, and the number of people they displace are all increasing. This is due to a number of factors, including climate change, drought, and human activity.

Climate change is making the Earth's climate hotter and drier. This creates ideal conditions for wildfires to start and spread. Drought also contributes to wildfires by making vegetation more flammable.

As this article will explore in more detail human activity, such as arson, campfires, and power line sparks, also play a major role in wildfire incidents.

How Do Wildfires Start Naturally?

Though overwhelmingly caused by humans, wildland fires can be naturally occurring. These causes can vary depending on a particular region’s climate, vegetation and topography. Natural causes of fires include lightning strikes, volcanic eruptions and fires being ignited by the sun’s heat. Let's delve a little deeper into some natural causes of wildfires:

1. Lightning

The most common cause among naturally occurring wildfires is lightning strikes. Lightning can hit power cables, trees, shrubs, or dry grass and cause forest fires to ignite.

According to the BBC, more than 12,000 dry-lightning strikes started over 650 wildfires across California in August 2020, burning more than 1.5 million acres of land, with hundreds of thousands of people evacuated.

2. Volcanic eruptions

Volcanic eruptions are another natural cause of forest fires. Hot magma from the earth’s crust is expelled as lava during a volcanic eruption, causing it to flow down mountainsides and spread out over the forest floor, starting fires.

Because the lava from a volcanic eruption has such a high temperature, it burns everything in its path and the fuel does not need to be very flammable.

3. Spontaneous Combustion

Decomposing organic materials, such as piles of dry leaves or compost, can produce heat over time. If the heat accumulates and reaches a critical point, it can ignite a fire. With increasing incidences of extreme weather events and therefore higher wildfire risk, this phenomenon is set to increase.

Where Do Wildfires Occur?

Wildfires can occur in various parts of the world, but they are most commonly associated with regions that have a combination of dry climates, abundant vegetation, and a history of fire activity. Some of the areas where wildfires are most common include:

  • Western United States: States such as California, Oregon, Washington, and parts of Nevada and Arizona are prone to wildland fires due to their dry summers, strong winds, and extensive forests.

  • Australia: The southern and eastern parts of Australia experience severe bushfires, especially during the hot and dry summer months. The country has a long history of devastating bushfires.

  • Mediterranean Europe: Countries like Spain, Portugal, Italy, and Greece have a Mediterranean climate characterized by hot, dry summers, which often lead to significant forest fires.

  • Amazon Rainforest: Portions of the Amazon basin, primarily in Brazil, experience wildfires, often caused by human activities like deforestation and land clearance.

  • Siberia and Russia: Siberia and parts of Russia witness large-scale wildfires, particularly in remote forested regions, during the summer months when the vegetation is dry.

  • Southeast Asia: Countries like Indonesia, Malaysia, and parts of Thailand and Vietnam experience wildfires, often associated with land clearing practices like slash-and-burn agriculture.

It's important to note that wildfires can occur in other regions as well, depending on local conditions, such as drought, high temperatures, and the presence of flammable vegetation. Additionally, climate change can influence fire patterns, making some regions more prone to increased fire activity.

The vast range of countries where Dryad Networks currently has reseller partners deploying Silvanet is testament to the growing number of regions that suffer from the scourge of forest fires.

How Do Humans Cause Wildfires?

As mentioned, people are to blame for the vast majority of wildfire instances around the world. What’s worse is that research suggests that human ignition is to blame for a staggering 97% of wildfires that threaten homes in the US.

Quoted in, Stijn Hantson, a fire ecologist at the University of California, said that human-caused wildfires spread twice as fast as naturally-caused ones, burn more intensely, and kill “double or triple” the amount of trees.

human caused wildfires statistic graphic

So, what is the most common cause of wildfires? Human carelessness is often the primary culprit. Arson, campfires, discarding lit cigarettes, playing with matches or fireworks are leading causes of wildfires: fires can be started either intentionally or through negligence.

1. Arson

A grim and sobering fact about forest fires is that many are started intentionally as acts of arson. Arsonists’ motives can be hard to discern, but are said to include real estate speculation, building land reclamation, and pasture management.

According to a report by the National Fire Protection Association, there were 52,260 intentional fires started between 2014 and 2018 in the US. These resulted in an estimated 400 civilian deaths, 950 civilian injuries, and $815 million in direct property damage each year.

2. Campfires

Campfires that are left unattended or that aren’t properly and completely extinguished are a common cause of human caused fires.

Left unattended, campfires can quickly get out of hand. They can then turn into wildfires themselves or emit burning embers and ash that spark fires nearby.

Campfires are often enforced by local authorities, who insist that they should only be held in rock-ringed fire pits and not until there are shovels and a plentiful supply of water nearby. However, these rules are often not adhered to and many campfires are started outside of designated campsites and areas, making them harder to control and manage.

Just as important as controlling the fires themselves is ensuring that they are properly put out. Simmering and sizzling embers can stay hot for hours (sometimes days) after a fire has ostensibly been extinguished. These can then be blown elsewhere by strong winds and are often still a hot enough heat source to start new fires. If this happens in hot, dry climates where there's a lot of vegetation, a blazing wildfire can start in no time.

One of the devastating forest fires caused by unattended campfires was the Ham Lake fire in 2007. As well as hundreds of properties, this fire burned down 75,000 acres of forest along the Gunflint Trail in northeast Minnesota.

3. Burning Debris

Burning debris in a forest

In a similar fashion, carelessness when it comes to debris burning can easily lead to a catastrophic uncontrolled fire. With the right weather conditions, people burning yard debris in their yards could easily spell a wildfire in the works. For example, wind can cause the flames rising from a pile of burning yard waste to unwanted areas, starting new fires.

Insufficiently extinguished fires again pose a significant fire risk. Fires can look like they’re completely burnt out, only for a smoldering ember to catch in the wind and start a whole new fire elsewhere.

4. Equipment, Machinery and Infrastructure

Research shows that broken or faulty power lines are the third most common cause of forest fires and are responsible for 10% of wildfires (approximately 400 fires) per year in California.

We already know that, in the right circumstances, all that’s needed to start a forest fire is a spark.

Equipment malfunctions and sparks from engines are a significant cause of forest fires around the world. For example, farm equipment or machinery used by construction companies are often to blame. While many such machines are now equipped with spark arrestors, these devices aren’t able to completely eradicate sparks, meaning they can still be blown astray and be capable of starting new fires.

For example, Zaca Fire (2007), the fifth biggest California wildfire on record, was caused by sparks from a metal grinder. The Carr Fire (2018) was ignited by sparks from a trailer's broken wheel rim and is the seventh-most destructive fire in California's history.

Zaca Fire and Carr Fire statistics graphic

5. Discarded Cigarettes

Lit cigarettes are often discarded from buildings and cars and these can ignite the dry vegetation on which they land, starting fires that can quickly spread.

In 2017 in the US alone, forest fires caused by discarded cigarette butts were responsible for $6 billion in property damage.


Wildfires are a pressing social, environmental and economic problem that’s getting worse. Responsible for 20% of global CO2 emissions, these fires emit more greenhouse gasses into the atmosphere than all forms of transport combined.

Public education and awareness campaigns doubtless have a key role to play in aiding people’s understanding of the causes and dangers of forest fires. This article has highlighted their primary causes around the world, both natural and human-caused.

Thankfully, technological solutions are coming to the fore. It goes without saying that the sooner the authorities can get to a fire, the easier to extinguish it will be. This is why early detection is so crucial in stopping fires from getting out of hand. And how fast do wildfires spread? Our previous blog showed that they can reach speeds of up to fourteen miles-per-hour, making their early detection ever more critical.

Ocular-based systems such as cameras, satellites and drones can be effective at tracking forest fires once they’ve started, but for early detection, they are often too late in raising the alarm. By the time they’ve seen a fire, it can be hours if not days since its ignition, more often than not resulting in a large-scale and very destructive wildfire scenario.

wildfire detection speed differences graphic

Increasingly, it looks as if sensor-based systems are the way forward. Dryad’s Silvanet technology is the fastest and most accurate solution when it comes to wildfire detection. Our new ultra-early detection technology detects wildfires at the smoldering stage and provides precise geographical data so that firefighters can locate and extinguish them quickly and safely.

Ultra-early wildfire detection technology has the potential to protect $30 billion in economic losses, stop 3.9 million hectares of vital forest from burning, save 237 million animals and prevent 10,000 respiratory cases by 2030.

Dryad's technology represents a game-changing approach to wildland fire prevention. As we face the escalating threat of wildfires, investing in and embracing such advanced detection systems will be crucial in safeguarding our communities and preserving our precious natural resources for generations to come.

Together, let us harness the power of innovation to build a future where forest fires are no longer an overwhelming menace, but a challenge we are well-equipped to overcome.

dryad's wildfire sensor on a tree

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