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What Causes Wildfires?

CRISIS - Biosystem Viability by Martina Igini Global Commons Apr 13th 20235 mins
What Causes Wildfires?

In recent years, stories of widespread wildfires are impossible to miss in climate change-related news. Unprecedented fires have destroyed millions of hectares of land, displaced hundreds of thousands of people, and eliminated entire habitats across the world. We take a look at what causes wildfires and what we can do to prevent them.

Even if you don’t closely follow the news, you would have heard of the unprecedented and record-breaking fires that have hit several regions across the globe in recent years. Between 2019 and 2021, immense wildfires burned down more than 1 million hectares of land in Siberia, killed nearly 3 billion animals in southeastern Australia, and took hundreds of buildings down across the US state of California

As we reflect on the consequences of these extreme events and study solutions to mitigate their impact and prevent them from happening on such a large scale, it is important that we understand what causes wildfires in the first place. 

You might also like: Top 12 Largest Wildfires in History

How Do Wildfires and Bushfires Start?

The risk of a fire developing is driven by three main factors: 

  1. Dry fuel such as leaves, grass, branches, and other organic materials
  2. Oxygen in the air
  3. Heat to ignite and burn

The latter can be a natural event, such as lightning strikes or spontaneous ignition, or it can be directly linked to human activities, such as vehicle fires, cigarette butts, or campfires. But what are the most common ignition sources of wildfires around the world?

Natural Causes of Wildfires

Lightning is the most common ignition source that causes the vast majority of wildfires. There are two types of lightning: cold and hot. Cold lightning is usually of short duration and thus rarely a cause of wildfires. The same cannot be said of hot lightning: currents in hot lightning have less voltage but occur for a longer period of time. Because of the intense heat it generates, hot lightning accounts for the majority of natural fires. While this natural phenomenon is completely unpredictable, adequate land management and landscape fire management planning can significantly diminish the intensity of wildfires and prevent unnecessary deaths and the displacement of people and animals. 

Climate change is undoubtedly the biggest trigger of extreme lightning storms. Warmer and longer summers heat up the land surface. This, coupled with an increase in carbon emissions, causes stronger updrafts that are more likely to produce more powerful and frequent lightning. A 2014 study estimates a 12% increase in the frequency of lightning strikes with every one degree Celsius increase in temperature.  

In Canada’s province of British Columbia, for example, hot lightning causes 60% of the region’s wildfires in an average year. The devastating and record-breaking 2020 Bay Area fire that destroyed 5 million acres of land, over 10,000 structures and killed 33 people was also a consequence of lightning storms. These hit the state following two intense heat waves which saw record high temperatures all over the west coast occurring over multiple days. 

As mentioned before, fuel is one of the three components needed for a wildfire to start. This often comes in the form of dry vegetation. Elevated temperatures and low winter-time precipitation often leave vegetation primed for wildfires. This was the case in California in 2021, which experienced a 65% rise in dry vegetation in just a few months. Similarly, several parts of Australia are characterised as a hot and dry climate and have recorded a steady decline in rainfall since 1970, making wildfires a regular occurrence. 2019 was the warmest year on record and it was accompanied by 43 extremely warm days. Not coincidentally, in the same year, the country experienced a bushfire crisis that resulted in the destruction of 11 million hectares of bush, forest, and parks in the states of New South Wales and Victoria. 

Human-Induced Wildfires

Humans are also often responsible for initiating wildfires, either accidentally or intentionally.  Human-related events that can ignite fires range from open burning such as campfires, equipment failure, and the malfunction of engines to debris burning, negligent discarding of cigarettes on dry grounds as well as other intentional acts of arson. The latter accounts for one of the most common causes of wildfires

According to government sources, 40% of wildfires that affect British Columbia in an average year are human-induced. In the US, the amount is more than double, with nearly 85% of the nearly 100,000 wildland fires that affect North America every year caused by human activities, according to data from the National Park Service. Here, man-made fires have tripled the length of North America’s fire seasons between 1992 and 2012, from 46 to 154 days. Over the 21-year study period, the major causes were debris burning and arson, while campfires and fireworks were responsible for ‘only’ 5% of fires. Furthermore, an analysis of more recent California fires found that human-sparked wildfires are more extreme and destructive than nature-induced ones as they move more than twice as fast, spreading about 1.83 kilometres per day. 

How Can We Solve the ‘Wildfire Pandemic’?

While almost all human-made wildlife fires are preventable, predicting Mother Nature is more complicated. However, every action to mitigate climate change and slow down global warming can effectively reduce the risk of extreme weather events such as lightning strikes and thus decrease the chances of wildlife fires. Furthermore, steady temperatures and rainfall can drastically reduce the amount of dry vegetation. 

Concretely, countries around the world are passing policies to regulate land management. In January 2022, the Biden administration announced a multibillion-dollar plan to make forests more resilient and reduce the risk of wildfires on up to 20 million hectares of land near vulnerable communities. The US government plans to do so by using thinning and intentional burning to restore forests and make them fire-adaptive. The move came after the Trump administration cut funding to research into the issue, undermining the risks of wildfires. 

As the burning of vegetation related to deforestation practices is among the leading causes of wildfires, environmental laws and policies that can provide critical backstops for ecosystems at risk, including forests, are also necessary. The Deforestation Pledge of more than 100 countries at the 26th annual United Nations Climate Change Conference (COP26) is certainly a step in the right direction. However, promising to end deforestation is not enough. Now, countries need to step up their efforts by lining up funding and quickly strengthening forest protection laws.

Keeping fires under control is crucial if we want to preserve wildlife and vegetation and avoid undesirable health problems and diseases caused by air pollution from smoke and ash. 

You might also like: 15 Worst Wildfires in US History

Tagged: wildfires

About the Author

Martina Igini

Martina is the Managing Editor at Earth.Org. She holds two BA degrees, in Translation/Interpreting Studies and Journalism, and a MA in International Development from the University of Vienna. After working at the United Nations Global Communication Department in Vienna, she joined a newspaper in Italy as a reporter before moving to Hong Kong in 2020. Her interests include sustainability and the role of public policy in environmental protection with a focus on developing countries.

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