# What Causes Wildfires and How They Can Be Prevented

> Canada's 2023 wildfire season burned around 18 million hectares, more than five times its ten-year average, while the UK's own wildfire risk has climbed sharply in recent dry springs. Here is the science behind why, and what actually reduces it.

*Section: Environment — By Elena Marsh (Environment & Climate Correspondent) — Published October 20, 2025, updated July 7, 2026 — 5 min read*

Canonical URL: https://dailyjunction.co.uk/environment/what-causes-wildfires-how-prevent
Tags: wildfires, climate change, land management, fire ecology, environment

## Key takeaways

- Canada's 2023 wildfire season burned an estimated 18 million hectares, more than five times its ten-year average
- London Fire Brigade had its busiest day since the Second World War during the record UK heatwave of 19 July 2022
- Wildfires need three conditions simultaneously — the fire triangle of fuel, ignition and weather — and IPCC research links climate change to how often all three align
- A century of active fire suppression policy since the mid-20th century has allowed fuel loads to accumulate in many forests, making eventual fires more intense
- Prescribed burning, used by Indigenous land managers for thousands of years, remains the most effective large-scale tool for reducing fuel loads

## Context: why wildfire coverage keeps intensifying

Wildfire has moved from a seasonal regional news story to a recurring global one, and 2023-25 gave the clearest recent illustrations of why. Canada's worst fire season on record blanketed North American cities in smoke thousands of kilometres from the fires themselves. The UK, not traditionally associated with serious wildfire risk, recorded its busiest fire service day since the Second World War during a record-breaking 2022 heatwave. Understanding the science behind both events — and why they are becoming more connected rather than isolated — matters well beyond the regions directly affected.

## The data: two case studies in a changing baseline

Canada's 2023 wildfire season burned an estimated 18 million hectares — more than five times the country's ten-year average — making it the most destructive fire season in Canadian recorded history by area affected. Smoke from the fires travelled across the continent, triggering air quality alerts in major US cities far from the fires themselves and putting the scale of the event in front of tens of millions of people who never saw a flame directly. Climate researchers widely cite the 2023 season as one of the clearest illustrations of how a warming, drying climate is extending and intensifying fire seasons in boreal forest regions specifically.

The UK's own exposure, while smaller in scale, has grown more visible. On 19 July 2022, UK temperatures exceeded 40°C for the first time on record, and London Fire Brigade recorded its busiest single day since the Second World War, responding to multiple simultaneous major fires including the Wennington blaze in east London, which destroyed several homes. Subsequent years with unusually dry UK springs have continued to elevate wildfire risk on moorland and heathland, with fire services issuing warnings outside the traditional summer peak period.

| Event | Location | Scale |
|---|---|---|
| 2023 wildfire season | Canada | ~18 million hectares burned, 5x+ ten-year average |
| 19 July 2022 heatwave fires | UK (London and surrounding areas) | Busiest London Fire Brigade day since WWII |

## The fire triangle: why fires need three things at once

Wildfires require three conditions simultaneously: fuel (dry vegetation), ignition (lightning or human activity) and weather conditions — low humidity, high temperature, wind — that allow a fire to spread rapidly once started. Climate change does not create fires directly, but it measurably increases how often all three conditions align, primarily by increasing the frequency and severity of heatwaves, droughts and low-humidity periods across fire-prone regions.

> "Climate change is less about starting more fires and more about creating far more days each year where any spark, however it starts, has the conditions to become a major fire rather than burning out quickly." — a distinction fire ecologists have increasingly emphasised as public understanding of wildfire risk has grown following successive record-breaking seasons.

## What's changing: a century of suppression meeting a warmer climate

The second driver, separate from climate change but compounding it, is land management history. Active fire suppression — extinguishing virtually every fire as quickly as possible rather than allowing smaller natural burns to run their course — became standard policy across much of North America, Australia and Europe through the 20th century. That policy has allowed fuel loads — accumulated dead wood and dense undergrowth that would previously have been periodically cleared by smaller natural fires — to build up in many forests to levels that produce unusually intense, hard-to-control fires once ignition does eventually occur.

Prescribed burning — deliberately igniting fires under controlled, monitored conditions to reduce fuel loads before they can feed an uncontrolled blaze — is consistently identified by fire ecologists as the most effective large-scale response. Indigenous communities in Australia and North America practised structured fire management for thousands of years before colonial-era suppression policy displaced those traditions, and land managers in both countries have increasingly incorporated Indigenous fire knowledge back into official wildfire management strategy over the past two decades.

## What it means for you

For UK households, the practical implication of the 2022 heatwave and subsequent dry springs is that wildfire risk assessment is no longer purely a southern-Europe or North America concern — homeowners near moorland, heathland or dense woodland, particularly in dry spring and summer periods, should be aware of local fire service advice on defensible space and tinder-dry vegetation near property, guidance that has expanded meaningfully since 2022. More broadly, the growing overlap between wildfire risk and [wider extreme weather patterns affecting the UK](/environment/climate-uk-extreme-weather-2026) means fire risk increasingly needs to be considered alongside flooding and heat risk as part of the same underlying climate trend rather than a separate, unrelated hazard.

Insurance markets are also beginning to price wildfire risk more explicitly in regions previously considered low-risk, mirroring a pattern already well established in flood insurance. Property insurers in parts of southern Europe and North America have introduced wildfire-specific exclusions, higher premiums, or in some cases withdrawn cover entirely from the highest-risk zones, a trend risk analysts expect to extend gradually to other regions, including parts of the UK, as wildfire frequency data accumulates over more fire seasons.

## What to watch next

Watch whether prescribed burning and fuel-load management programmes scale up meaningfully in high-risk regions, given they remain chronically underfunded relative to the cost of firefighting the large blazes they are designed to prevent — a mismatch fire ecologists have long flagged as a policy failure. Also watch whether UK spring rainfall patterns continue trending drier, since several of the driest UK springs on record have occurred within the past decade, a pattern consistent with — though not definitively proof of — the broader climate trends already reshaping [where and how populations are being displaced by environmental change globally](/environment/climate-migration-environmental-displacement).

## Frequently asked questions

### How bad was Canada's 2023 wildfire season, specifically?

Canada's 2023 wildfire season was its most destructive on record by area burned, with an estimated 18 million hectares affected — more than five times the country's ten-year average. Smoke from the fires drifted across large parts of North America, triggering air quality alerts as far south as major US cities, and the season is widely cited in climate research as one of the clearest recent illustrations of how warming and drying trends are extending and intensifying fire seasons in boreal forest regions.

### Can the UK actually have serious wildfires, or is this mainly a problem elsewhere?

The UK can and does have serious wildfires, though at a smaller scale than Australia, Canada or the Mediterranean. The record UK heatwave of 19 July 2022, when temperatures exceeded 40°C for the first time on record, triggered London Fire Brigade's busiest day since the Second World War, including the Wennington fire that destroyed multiple homes in east London. Dry UK springs in subsequent years have continued to elevate wildfire risk in areas including moorland and heathland, prompting fire service warnings even outside the traditional summer peak.

### Is climate change actually the main driver, or is it mostly about forest management?

Both factors matter and interact rather than compete as explanations. Climate change increases the frequency of the hot, dry, low-humidity conditions that make fires more likely to start and spread rapidly. Separately, a century of active fire suppression policy in many countries — putting out virtually every fire as quickly as possible rather than allowing smaller natural burns — has allowed fuel loads (dead wood, dense undergrowth) to build up to levels that produce unusually intense fires once ignition does occur. Climate change and historic suppression policy together explain most of the recent trend better than either does alone.

### What actually works to reduce wildfire risk at scale?

Prescribed burning — deliberately igniting fires under controlled conditions to reduce accumulated fuel loads before they can feed an uncontrolled blaze — is consistently identified by fire ecologists as the most effective large-scale tool, and has been practised by Indigenous communities in Australia and North America for thousands of years before European settlement disrupted those land management traditions. Mechanical thinning and undergrowth removal near communities also reduces risk but is more expensive and needs regular repetition to remain effective.

## Sources

- [Natural Resources Canada — 2023 wildfire season summary](https://natural-resources.canada.ca/simply-science/wildfires-canada/25303)
- [London Fire Brigade — record heat 19 July 2022 incident summary](https://www.london-fire.gov.uk/news/2022-news/)
- [IPCC — climate change and extreme weather assessment](https://www.ipcc.ch/report/ar6/wg1/)

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