Wildfires - An escalating challenge across the globe
A wildfire is an uncontrolled fire that burns in the wildland vegetation, often in rural areas. Wildfires can burn in forests, grasslands, savannas, and other ecosystems, and have been doing so for hundreds of millions of years. They are not limited to a particular continent or environment.
- National Geographic
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Fire can be incredibly useful for us humans.
However, using fire requires much awareness of safety, because it can also be incredibly dangerous and destructive. Even a single spark in a dry forest can start a wildfire that engulfs hundreds of thousands of acres. Although lightning strikes can cause wildfires, most wildfires are caused by humans: cigarettes, malfunctioning electrical equipment, trash burning, and poorly extinguished campfires are just some ways wildfires can ignite. Depending on the weather, small sparks can wipe out entire forests and cities within days, destroying everything in their path and polluting the air with smoke thick enough to be seen from space.
Wildfires are also becoming more intense and more frequent, destroying communities and ecosystems in their path. Recent years have seen record-breaking wildfires across the world from Australia to the Arctic to North and South America. With global temperatures on the rise, the need to reduce wildfire risk is more critical than ever. Uncontrollable and extreme wildfires can be devastating to people, biodiversity and ecosystems. They can also have a large effect on climate change, contributing significant greenhouse gasses to the atmosphere.
Wildfires and climate change
Across Earth’s ecosystems, wildfires are growing in intensity and spreading in range, causing havoc on the environment, wildlife, human health, and infrastructure. According to the UN environment program report (2022), the Earth has since the industrialisation experienced a long-term warming trend, with an estimated increase in the global mean surface temperature of 1.09°C (IPCC 2021). Some areas of the planet have experienced accelerated warming with an increase of 1.59°C over land and, for example, temperatures in the Arctic rising more than twice as fast as the global average (IPCC 2018; IPCC 2021).
Warming has increased the frequency and magnitude of extreme weather conditions that drive the occurrence and spread of wildfires and has caused vegetation that would not usually burn to dry out and combust (e.g., rainforests, permafrost, and peat swamps). A review of 116 articles written since 2013 on climate change and fire concluded that there is a strong consensus that climate change is increasing the likelihood of fire occurrence in many regions (Smith et al. 2020).
Fire behaviour triangle - the key variables that affect how a wildfire behaves
The fire behaviour triangle (Clive Countryman 1972) illustrates the key variables that affect how a wildfire behaves. All combustible materials are fuel for the fire, mainly live and
dead plant material, and constructions in WUI fires. Weather influences fire through the effects of wind, temperature, and humidity. Topography or land shape can hinder or help the spread of fire and influence the speed of fire and the type and condition of the fuel. Together, these variables influence the behaviours like speed, direction, flame characteristics and intensity of a fire.
Wildfires and biodiversity
Not all fires fires need to be extinguished as they serve important ecological purpose. In some areas regular conflagrations play a key role in driving and maintaining the area’s biodiversity. Plants can be dependent on fire and some animals depend on those plants, other animals depend on that animal and so on. There is an entire structure of dependency.
After a fire, the open space in a forest and additional sunlight makes trees and plants grow and nutrients are returned to the soil through the ashes of vegetation.
Controlled burning can also prevent destructive wildfires by removing dead materials that would act as fuel to a fire.
The idea is that some wildfires are allowed to burn because of their positive effect on biodiversity.
Koala bear escape from australian bushfire.
Credits: Benny Marty / Shutterstock
Australian plants regenerating after catastrophic fires.
Credits: DMV Photography / Shutterstock
Honeybee on a mint plant.
Credits: Benny Marty / Shutterstock
However, wildfires that burn for weeks and that may affect millions of people over thousands of square kilometres
present a major challenge. Wildfires are burning longer and hotter in places they have always occurred, and are flaring
up in unexpected places, like drying peatlands and in permafrost areas. These large fires can be really devastating
for important biodiversity areas, that might never fully recover again.
Not only can wildfires contribute to a climate change feedback loop by emitting huge quantities of greenhouse gases
into the atmosphere, but also greatly reduce biodiversity.
Fire in Transbaikal forest.
Credits: Lu Yago / Shutterstock
Forest fires could result in an irreversible degradation of permafrost.
It may take decades or even centuries for the fire-disturbed ecosystems and
permafrost environment to return to pre-fire conditions, if ever possible.
In boreal forest, the thickness of organic layer has a key influence on
changes in permafrost and vegetation.