Wildfires are uncontrolled fires that burn through vegetation in forests, grasslands and scrublands. They are a natural part of many ecosystems, but a warming climate, prolonged drought and expanding human settlement are making them larger, more frequent and more deadly — a growing hazard on every continent except Antarctica.

What causes wildfires?

Wildfires require three conditions to start and spread — sometimes called the "fire triangle": a source of fuel, a source of ignition and conditions (weather and physical environment) that allow the fire to spread. Understanding each helps you explain why particular places are at risk.

Fuel is any combustible vegetation: grass, shrubs, dry leaf litter, forest trees. The more vegetation, the higher the fuel load. Drought dries out vegetation and reduces moisture content, making it ignite more easily. After a wet growing season followed by a dry period, an exceptionally large fuel load can accumulate.

Ignition can be natural or human-caused. Lightning is the most common natural ignition source. Human ignition — careless campfires, discarded cigarettes, arson, agricultural burning, sparks from machinery, power line failures — accounts for around 85% of wildfires in the USA and a similar proportion in southern Europe and Australia.

Spreading conditions include: dry air (low humidity), high temperatures and wind. Wind is particularly dangerous: it dries vegetation ahead of the fire, carries embers that start new fire fronts (spotting), and supplies oxygen to the combustion. The combination of extreme heat, low humidity and strong wind creates the conditions for the most destructive wildfire events.

Which environments are most at risk?

Some environments are inherently more fire-prone due to their climate, vegetation type and human land use.

Environment Why prone to wildfires Example locations
Mediterranean climate zones Hot, dry summers; dense combustible shrubland (maquis/chaparral); strong winds (Mistral, Santa Ana) California, southern France, Greece, southern Australia, South Africa's fynbos
Savanna grasslands Long dry season; grass dries to fine fuel; lightning ignition common Sub-Saharan Africa, northern Australia, Brazil's Cerrado
Boreal (taiga) forests Periodic drought; dense conifer forests with resin-rich wood; warming faster than global average Siberia, Canada, Alaska, Scandinavia
Temperate grasslands and heathlands Periodic drought; fine fuels; human ignition common UK moorlands, US Great Plains

The UK has significant wildfire risk on moorlands and heathlands, particularly in Scotland, Wales, the Peak District and Dartmoor — a fact often surprising to students who associate wildfires with distant continents. Warm, dry, windy springs and early summers create conditions for damaging UK wildfires.

What are the effects of wildfires — using the SEEP framework?

Social effects:

  • Evacuations of communities, sometimes at short notice; trauma and mental health impacts
  • Deaths and injuries from fire, smoke inhalation and road accidents during evacuation
  • Loss of homes and community infrastructure (schools, utilities)
  • Displacement of communities for weeks or months; some may not return
  • Reduced air quality from smoke over large areas, affecting respiratory health hundreds of kilometres away

Economic effects:

  • Direct property damage — the 2018 Camp Fire in California destroyed the town of Paradise (approximately 18,800 buildings) and caused estimated losses of over US$16 billion
  • Loss of agriculture, livestock and timber industry assets
  • Tourism revenue losses in affected landscapes
  • Firefighting costs: California alone spends US$3–4 billion annually on wildfire suppression
  • Increased insurance premiums; some insurers have withdrawn from high-risk markets entirely

Environmental effects:

  • Loss of biodiversity and habitat destruction; some species unable to recolonise burned areas quickly
  • Soil erosion increases dramatically after fire removes protective vegetation cover; subsequent rainfall causes mudslides and floods
  • Release of stored carbon to the atmosphere — forests are major carbon stores and large wildfires can release carbon equivalent to a country's annual emissions
  • Ash and debris contaminate rivers and water supplies
  • Some ecosystems are adapted to fire and recover well; others — particularly older forests — take centuries to recover fully

Political effects:

  • Pressure on governments for increased firefighting resources and prevention investment
  • Debates about forest management policy (prescribed burning, clearing fuel breaks)
  • Cross-border issues: smoke from Russian wildfires affects China and Japan; Canadian wildfires produce smoke over the US East Coast
  • Climate change politics: wildfires increasingly cited in arguments for stronger emissions reduction

How is wildfire risk managed?

Wildfire management divides into prevention, preparedness, response and recovery.

Prevention includes:

  • Prescribed burns (also called controlled burns): deliberately setting low-intensity fires when conditions are manageable to consume accumulated fuel before it builds to dangerous levels. This mimics natural fire cycles. Indigenous communities in Australia and North America have used this technique for thousands of years.
  • Fuel breaks and fire roads: strips of cleared or low-fuel vegetation that stop or slow fire spread and provide vehicle access for firefighting
  • Building regulations requiring fire-resistant construction materials in high-risk zones
  • Power line management: burying lines or installing automatic shutoffs in high-risk conditions (power line failures caused several of California's worst recent wildfires)
  • Public education about fire behaviour, campfire regulations and reporting

Response has evolved significantly with technology:

  • Air tankers and helicopters dropping water and fire retardant
  • Satellite monitoring and remote sensing to track fire spread in real time
  • Early warning systems and evacuation apps
  • Coordinated ground firefighting with specialist crews (including international cooperation during major events)

Recovery includes erosion control (applying mulch or seeding bare slopes before rain), removal of unstable fire-killed trees, community rebuilding support and long-term ecological restoration.

How is climate change changing wildfire risk?

Climate change is a multiplier of wildfire risk, not a direct cause. Its effects work through several mechanisms:

Higher temperatures dry vegetation faster, extend fire seasons and increase the frequency of extreme fire weather days. In southern Europe, Australia and California, fire seasons are measurably longer than fifty years ago.

Drought is increasing in frequency and duration in many fire-prone regions, reducing soil and vegetation moisture and building up dry fuel loads.

Changed precipitation patterns — more intense rainfall followed by longer dry periods — can paradoxically increase wildfire risk. Heavy rainfall promotes rapid plant growth; prolonged drying then converts that growth into fine dry fuel.

Permafrost thaw is releasing peat in high-latitude areas (Siberia, Canada) where deep organic soils had been frozen; these peat fires can burn underground for months or years, releasing large amounts of carbon.

The feedback loop this creates — wildfires releasing carbon, which warms the climate, which creates conditions for more wildfires — is one of the most concerning potential tipping points in climate science.

Frequently asked questions

Are wildfires always harmful to ecosystems?

No. Many ecosystems evolved with fire and depend on periodic burning for healthy function. In Australian eucalyptus forests, some plant species require fire heat to release seeds from seed pods; giant sequoias in California need fire to open their cones and clear competition. Savanna grasslands are maintained by fire; without it, they would gradually succeed to woodland. The problem for ecosystems today is not fire itself but fire that is too frequent, too intense or occurring in areas not adapted to it — particularly old-growth forests and peatlands that store large amounts of carbon.

Why are wildfires getting worse in the UK?

UK wildfire risk has increased because warming, drying springs and early summers — combined with large areas of moorland and heathland managed for grouse shooting (which involves regular burning) — create conditions for damaging fires. The April 2019 Saddleworth Moor fire and the summer 2022 grass fires across England (the UK's hottest summer on record, at 40.3°C in Coningsby, Lincolnshire) highlighted the UK's exposure to a hazard previously considered primarily a foreign concern. The UK government's wildfire risk guidance was updated in 2022 to reflect these changing conditions.

What is the difference between a wildfire and a forest fire?

"Forest fire" refers specifically to fires in forested areas. "Wildfire" is a broader term covering any uncontrolled fire in natural or semi-natural vegetation — including grasslands, heathlands, scrublands and agricultural stubble, as well as forests. Geographers typically use "wildfire" as the inclusive term because significant fires occur in non-forested environments and the underlying causes and management approaches share common features.

Why do some communities choose to stay in fire-prone areas?

The decision to live in fire-prone areas (sometimes called the "wildland-urban interface") reflects a mix of economic, social and perceptual factors. Property is cheaper in some high-risk areas (until insurance makes it more expensive). Communities have deep historical and cultural ties to landscapes. People often underestimate risk or believe management measures will protect them. In some cases — particularly in poorer communities — there is simply no affordable alternative. The combination of expanding settlement into fire-prone areas and increasing fire risk due to climate change is one of the most significant environmental policy challenges in countries like the USA, Australia and Spain.

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