PARIS - The frequency and severity of extreme wildfires, as well as the duration of the fire season, are increasing in many parts of the world, threatening lives, livelihoods and ecosystems.

A new OECD report, launched during the 8th International Wildland Fire Conference in Porto, provides a global assessment and outlook on wildfire risk in the context of climate change, underlining the need to scale up wildfire prevention and climate change adaptation efforts to limit future wildfire costs.

Building on country case studies carried out in Australia, Costa Rica, Greece, Portugal and the United States, the report provides a set of policy recommendations to strengthen wildfire risk reduction in OECD countries and beyond.

Executive Summary

The frequency and severity of wildfires, as well as the duration of the fire season, are increasing in many regions of the world. The occurrence of extreme wildfires – i.e. wildfire events that are particularly severe in terms of their size, duration, intensity and impacts – is also on the rise. In Australia, the average wildfire frequency has doubled since 1980. In the forests of the western United States, wildfire severity, i.e. the degree of ecosystem impacts caused by a fire, increased eightfold between 1985 and 2017. The duration of the fire weather season has increased by 27% globally since 1979.

Climate change is exacerbating extreme wildfire risk. Higher atmospheric temperatures, variable precipitation patterns, the dryness of the landscape, and changing wind and lightning patterns have increased the risk of wildfires. Climate change is estimated to have doubled the total forest area burned in the western United States between 1984 and 2015. The extreme fire weather that facilitated the 2019-20 wildfires in Australia was estimated to be at least 30% more likely because of climate change. Moreover, emissions from extreme wildfires fuel climate change, which in turn further increases the frequency, size and severity of wildfire events, creating a feedback loop between climate change and extreme wildfires.

Unsustainable land-use practices and environmental degradation have also affected natural ecosystems’ resilience to wildfires. Deforestation and the drainage of peatlands worsen drought conditions and increase landscape flammability, thereby contributing to the occurrence of extreme wildfires in countries such as Brazil and Indonesia. Certain agricultural and forestry practices also increase wildfire risk, as evidenced in 2017 in Portugal, where non-native eucalyptus provided highly flammable fuel. In most cases, human activity is also the main cause of wildfire ignition, responsible for nearly 70% of the total burned area globally.

Extreme wildfires cause significant social, environmental and economic disruptions. Their social costs go far beyond lives lost and include widespread health impacts. For example, at the global level, wildfire-induced air pollution is associated with 340 000 premature deaths annually. Extreme wildfires can also cause long-lasting and potentially irreversible ecosystem damage. Following the 2017 wildfires in Chile, nearly 40% of critically endangered habitats were significantly damaged, while the area where vegetation did not grow back after wildfires nearly doubled between 2000 and 2011 in some areas of the United States. The economic impacts of extreme wildfires are also mounting to unprecedented levels. The 2018 California Camp Fire caused around USD 19 billion in direct costs, while the 2019-20 wildfires in Australia caused USD 23 billion in direct costs.

The occurrence of extreme wild res is growing

The frequency and severity of wild res, as well as the duration of the re season, are increasing in many regions of the world. The occurrence of extreme wild res, which are wild re events that are particularly severe in terms of their size, duration, intensity, and impacts, is also on the rise. In Australia, the average wild re frequency has doubled since 1980. In the forests of the western United States, wild re severity,

which is the degree of ecosystem impacts caused by a wild re, increased eight-fold between 1985 and 2017. Globally, the duration of the annual re weather season has increased by 27% since 1979.

Extreme wild res a ect humans, nature and the economy

While in some areas wild res provide important ecological functions that maintain ecosystem health and functioning, extreme wild res threaten the natural balance of ecosystems and can tip them towards irreversible changes. Altogether, extreme wild res can cause signi cant impacts on human lives and well- being, on ecosystems and the climate system, as well as on the economy.

Globally, wild re-induced air pollution is associated with 340 000 premature deaths annually. Extreme wild res can cause long-lasting and potentially irreversible ecosystem damage as observed during the 2017 wild res in Chile, where nearly 40% of critically endangered habitats were damaged. The economic impacts of extreme wild res are also mounting to unprecedented levels. The 2019-2020 wild res in Australia caused
USD 23 billion in direct economic damages - the costliest in the country’s history.

Climate change exacerbates wild re risk

Higher atmospheric temperatures, altered precipitation patterns, dryness of the landscape, and changing wind and lightning patterns have increased the risk of wild res:

• Droughts were found to drive the intensity of the 2017 wild res in Chile and Portugal, the 2018 Camp Fire in the United States, and the 2020 wild res in Arctic Siberia, Russian Federation (hereafter “Russia”)

• Exceptionally high atmospheric temperatures were associated with the occurrence of the 2019 Arctic wild res in Canada and the 2018 wild res in Australia.

• The 2019-2020 wild res in Australia were found to be at least 30% more likely due to climate change.

Extreme wildfires in turn contribute to climate change

Extreme wild res can alter the Earth’s carbon cycle, emitting more carbon than is sequestered by regrowing vegetation. Carbon dioxide (CO2) emissions from extreme wild res amount to an average 8 billion tonnes every year. At the same time, by burning vegetation and soil, extreme wild res in forests and peatlands reduce land carbon storage capacity, further hampering climate mitigation e orts. Thereby, wild res exacerbate climate change, which in turn increases the frequency, size, and severity of wild re events.

For the full report, visit:https://www.oecd-ilibrary.org/sites/dd00c367-en/index.html?itemId=%2Fcontent%2Fpublication%2Fdd00c367-en&utm_campaign=env-news-22-may&utm_content=Wildfires%20report%20URL&utm_term=env&utm_medium=email&utm_source=Adestra