UK and Global Fire Weather
Investigating the causes and impacts of wildfires, in the UK and worldwide
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, like the wildfires in 2022, Colorado. This was the most destructive wildfire ever to impact the state, as powerful winds fanned a fast-moving wildfire with devastating impact to the community.
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. In 2021, Death Valley, recorded a record 54.4 degrees, - one of the hottest spells on record. A massive blaze burned through more than 220,000 acres in California.
Parts of Europe experienced intensely high summer temperatures in 2021, and wildfires caused devastation in Turkey, Greece and Sicily, where temperatures reached 48.8°C, beating the previous European high of 48°C recorded in Athens in 1977. A Met Office-led attribution study of the European summer of 2021 shows such seasonal summer temperatures would have been impossible without human-induced climate change.
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.
Latest Climate Science of Wildfire
A new UNEP report, "Spreading like Wildfire: The Rising Threat of Extraordinary Landscape Fires", has predicted that there could be a substantial increase in wildfires around the world by the end of the century. The report found that some of the biggest increases will be in areas not typically used to seeing wildfires, such as the Arctic and central Europe. Areas of tropical forest in Indonesia and the southern Amazon are also likely to see increased burning if greenhouse gas emissions continue at their current rate.
Scientists at the Met Office and the UK Centre for Ecology & Hydrology carried out modelling to predict future increases in wildfires for the report. They found that even if greenhouse gas emissions are reduced, there are likely to be more wildfire events by 2100 because global temperatures would continue to rise to 1.5 to 2 degrees Celsius higher than pre-industrial times under the Paris Agreement. There is projected to be a global increase of extreme fires of up to 14 per cent by 2030, 30 per cent by 2050 and 50 per cent by the end of the century.
Met Office climate scientist and contributing author to the UNEP report, Dr Chantelle Burton, said:
“We are already seeing the impact of climate change on weather patterns all over the world, and this is disrupting normal fire regimes in many regions. It is important for fire research to explore what is changing, what effect this could have on people and the environment, and what communities need to do to prepare.”
Dr Douglas Kelley, Land Surface Modeller at the UK Centre for Ecology & Hydrology and lead data analyst for the report, said:
“Wildfires can significantly affect the global carbon cycle. Fires in ecosystems that store large amounts of carbon result in the release of vast quantities of CO2 into the atmosphere. This exacerbates global warming, which in turn increases the risk of wildfires."
“Reducing global greenhouse gas emissions will avoid some of the biggest increases in wildfires in forests, peatlands and permafrosts, which will help limit warming and fires, as well as the impacts of people and wildlife.”
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.
Met Office led research examines trends in UK wildfire occurrences
Historically, UK wildfires were most closely associated with spring. Research led by Met Office Scientist Matthew Perry, indicates a large projected increase in hazardous fire weather conditions in summer, with a possible extension of the wildfire season into late summer and early autumn. The paper’s findings conclude that wildfire can be considered an ‘emergent risk’ for the UK, with adaptation actions being required to manage the future risk. Whilst the results do not take account of specific human and fuel factors, they do highlight a large increase in risk between 2 °C and 4 °C of global warming, highlights the importance of global efforts to keep warming below 2 ◦C.
Influence of climate change on wildfire conditions and occurances
In 2020, South America experienced 458,953 fires, the highest number since 2010. Extreme heat in Siberia triggered widespread fires, with 1.15 million hectares burning in late June, associated with a release of about 56 million tonnes of carbon dioxide - more than the annual emissions of some industrialised countries such as Switzerland and Norway. A rapid attribution study led by researchers from international universities and meteorological services, including the P.P.Shirshov Institute of Oceanology, Russian Academy of Science, concluded this prolonged heat would have been almost impossible without the influence of human-caused climate change.
Prof. Olga Zolina, P.P.Shirshov Institute of Oceanology, RAS, Moscow, and CNRS Institut des Géosciences de l’Environnement, Grenoble, lead author IPCC AR6:
“This study shows that not only was the magnitude of the temperature extremely rare but also the weather patterns that caused it. We are continuing to study how the wildfires that have burned over thousands of hectares might also affect the climate as the flames pump smoke and ash into the atmosphere.”
During the 2019-2020 fire season in Australia, 45 million acres of land was burned destroying homes and causing deaths of people and vast numbers of animals. The Bureau of Meteorology and CSIRO State of the Climate Report 2020 showed Australia had seen an increase in extreme fire weather, and in the length of the fire season, across large parts of the country since the 1950s, especially in southern Australia.
In light of the Australian fires, in January 2020 an international group of scientists, including from University of East Anglia (UEA), Met Office Hadley Centre, University of Exeter, Imperial College London, and CSIRO Oceans and Atmosphere reviewed published scientific evidence and concluded there is consistent evidence that hot dry weather conditions promoting wildfires are becoming more severe and widespread due to climate change.
Professor Richard Betts, Head of Climate Impacts Research at the Met Office Hadley Centre and co-author of the review, said:
“Fire weather does occur naturally but is becoming more severe and widespread due to climate change. Limiting global warming to well below 2°C would help avoid further increases in the risk of extreme fire weather.”
Using science to inform fire risk strategies
Researchers at the Met Office collaborate with organisations and institutions in the UK and across the globe to support planning strategies and reduce the risk and impact of fires.
CSSP Brazil fire probability forecasting
Launched in 2016, the Climate Science for Service Partnership Brazil (CSSP Brazil) is a research project that aims to build strong partnerships between research institutes in the UK and Brazil. The project produces collaborative science that is fundamental to the development of climate services that support climate-resilient economic development and social welfare.
As part of the Climate Science for Services Partnership (CSSP) Brazil project, researchers are studying how wildfire occurrence in South America may change in the future. One of the successful outcomes of the project has been the development of seasonal fire probability forecasts for South America.
Led by Brazil’s National Centre for Monitoring and Alerts of Natural Disasters (CEMADEN) in collaboration with the Met Office and the Instituto Nacional de Pesquisas Espaciais (INPE), the project used the Met Office seasonal forecast to analyse temperature and rainfall probability, together with fire trend data, and developed a method of calculating fire probability for South America several months ahead.
To support planning strategies to reduce the risk and impact of fires, the researchers used the seasonal forecast to produce reports for decision makers on fire probability for areas of interest. The reports focus on South America’s protected areas which have high biological, environmental and sociocultural value, and the information presented in the reports could help guide actions on the ground.
With input from Met Office researchers, the paper “An alert system for Seasonal Fire probability forecast for South American Protected Areas”, looked at how a key component in the prevention and monitoring of fires in South American Protected Areas was the provision of timely, spatially explicit warnings to areas with a high fire occurrence probability. The study proposes a five-level alert system, combining the two main drivers of fires in South America - climatological and anthropogenic factors.
England & Wales Fire Severity Index (FSI)
The Fire Severity Index (FSI) is a Met Office bespoke service, designed to fulfill 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).
Delivered through the Met Office Hazard Manager and Resilience Direct, the Natural Hazards Partnership’s Daily Hazard Assessment provides an at-a-glance overview of potential natural hazards which could affect the UK. Covering a 5-day period, this assessment provides a summary which aims to improve the UK’s resilience and preparedness for multi-hazard events. The assessment comprises 21 natural hazards, including fires, all of which are assessed using the Hazard Matrix which contains links and further information on each of the highlighted hazards.