UK and global wildfire causes and impacts

The latest report from the Intergovernmental Panel on Climate Change states that “it is unequivocal that human influence has warmed the atmosphere, ocean and land.” 

We have already seen average global land temperatures increase over 1 °C since the Industrial Revolution. As a result of this baseline increase in temperature, we are seeing extreme heat events, such as heatwaves and record-breaking high temperatures, become more frequent, long-lasting, and intense. 

Our climate system is finely balanced, and small changes can have significant consequences. Whilst a 1 °C background temperature increase may not seem significant, the resulting increase in the severity of extreme heat events has widespread and significant impacts.  

Such hotter, drier weather has increased the scale, intensity, and frequency of destructive wildfires in many regions worldwide. Wildfires significantly impact people, ecosystems, and the climate. They affect air quality, impact forests, savannahs, and grasslands, and create hazards for the people and infrastructure surrounding them. 

Influences on fire: ignition, fuel and weather conditions 

Higher temperatures alone will not necessarily lead to more fires. Fires depend on a combination of available fuel, fire weather conditions, and an ignition source, either by human influence or lightning strikes. Vegetation provides the fuel for fires, and both the amount of vegetation and its level of dryness are important. Moist, live vegetation burns less readily whereas dry, dead vegetation is more likely to catch fire and allow the fire to spread. 

The weather therefore plays a critical role. High winds cause fires to spread faster, and wildfires are more severe during extended periods of hot dry weather, because higher temperatures cause more evaporation and this dries the vegetation, creating fuel for the fires.

Professor Peter Stott, Science Fellow in Climate Attribution at the Met Office Hadley Centre, said: “We can be more confident than we've ever been about linking extreme weather events to climate change. The increasing chances of these extreme events continue to rise as long as we continue to emit greenhouse gases. The science is clear that the faster we reduce our emissions of greenhouse gases, the more we can avoid the most severe impacts of climate change.” 

Climate change may also lead to wetter conditions in some places, as warmer air can hold more moisture, which can affect fuel availability and flammability. 

There are management actions that can be taken to mitigate the risk of wildfires and their impact, but it is practically impossible to entirely remove the risk posed by wildfires. Consequently, more communities around the world must learn to live with the residual risk of wildfire and plan appropriately to minimise the disruption it may cause.  

State of Wildfires 2024-2025 report

The second annual State of Wildfires report - co-led by the UK Centre for Ecology & Hydrology (UKCEH), the Met Office, the University of East Anglia (UEA) and the European Centre for Medium-Range Weather Forecasts (ECMWF) – was published in October 2025. The scientists used satellite observations as well as advanced modelling to identify and investigate the causes of wildfires from the last fire season (March 2024-February 2025) and the role that climate and land use change played.

UKCEH land surface modeller Dr Douglas Kelley, who co-led the report, said: “Our annual reports are building unequivocal evidence of how climate change is increasing the frequency and severity of extreme wildfires. Without human-driven warming, many of these wildfires, in Pantanal and Southern California, for example, would not have been on an extreme scale.”  

England & Wales Fire Severity Index (FSI) 

The Fire Severity Index (FSI) is a Met Office bespoke service, designed to fulfil Natural England land access obligations under the Countryside and Rights of Way (CROW) act. Calculated using information such as wind speed, temperature, time of year and rainfall, the index provides an assessment of how severe a fire could become if one were to start. The FSI acts as a trigger for enforcing fire prevention restrictions on access land under the CROW act. These restrictions aim to minimize the risk of accidental fires on vulnerable access land by suspending open access rights when conditions become exceptional (FSI level 5).