Prolonged and severe heatwaves and wildfires are worrying examples of the likely consequences of a climate crisis. The recent tragic events in Hawaii, and the fires that burned in parts of Canada, have again underlined the seriousness of the threat of wildfires in many regions across the world. The Science and Natural Perils team at 色多多视频describe the challenges in understanding wildfire risk and how climate change may affect this destructive natural peril.
A series of destructive wildfires across various regions of the world have resulted in the tragic deaths of hundreds of people or displacement of many others so far this year. These events serve as a reminder of the devastation that can be wrought by this natural peril.
Wildfires are by no means a new risk, but recent high-profile events, coupled with changes in exposure and the potential impacts of climate change, have highlighted the need for clients and underwriters to better understand this peril. The 2022 Intergovernmental Panel on Climate Change’s Assessment Report highlighted wildfires as a natural peril that is highly likely to be aggravated by global warming.
In August this year, wildfires in Hawaii tragically resulted in the deaths of at least 97 people and significant damage or destruction to more than 2,700 buildings, and an estimated US$5.5 billion in economic damage. Abnormally dry conditions combined with near hurricane-strength winds led to deadly fires that tore quickly through residential neighbourhoods.
Canada has also been experiencing its worst ever wildfire season this year, with 1,000 active fires still burning in British Colombia and the Northwestern Territories in September. The wildfires have damaged more than 200 structures and homes in British Colombia alone and scorched about 18 million hectares – an area equivalent to the size of New York State. The area burned is more than double any previous year since 1983 and more than 10 times more than last year, according to the Canadian Interagency Forest Fire Centre. Europe too has seen devastating wildfires this year. A heatwave in July led to soaring surface temperatures across many Mediterranean regions, drying out vegetation and leading to wildfires in Greece, Italy and Serbia that caused widespread damage. Greece was particularly badly affected, with more than 82 wildfires reported and about 20,000 people forced to evacuate from the island of Rhodes, and a further 2,000 from the island of Cos, during peak holiday season.
Heatwaves and wildfires are not new phenomena in Greece, but the area burned by wildfires in 2023 was already twice the annual average by July.
As well as the environmental devastation wildfires can cause, the economic and insured costs of wildfires can be huge. The Camp Wildfire event in California in 2018, for example, destroyed about 18,000 homes and buildings causing US$16.5 billion in economic damage and US$12.5 billion in insured losses, according to Munich Re data.
Australia’s so-called ‘Black Summer’ of 2019/2020, devastated large areas of New South Wales, Victoria and the Australian Capital Territory, burning more than 18 million hectares of bush and woodland, - an area the size of Syria. This resulted in record breaking economic losses of more than US$2 billion, about 75% of which were insured, according to Munich Re.
How do wildfires start and spread?
Fundamentally, wildfires require three elements to start and spread:
• Combustible material, like dry land, grass or leaves;
• Ignition, which can be either caused by human activity like dropping cigarette butts, out-of-control campfires, or powerline failures, or by natural factors such as lightning strikes; and
• Oxygen.
The ignition and the spread of a wildfire depends on several factors, including the prevalent weather conditions, the landscape, and the availability of fire-suppression resources nearby, for example.
While the full extent of climate change on changes in wildfire risk is not yet fully understood, it is highly likely that rising temperatures, prolonged heatwaves and droughts, and changing precipitation patterns are all playing a role in exacerbating wildfire risk.
Heatwaves are becoming more frequent, longer- lasting and more intense. And the combination of hot and dry weather creates the perfect conditions for wildfires to ignite and spread rapidly.
In addition to creating conditions that aid the spread of wildfires, a changing climate may also impact the natural ignition of wildfires. For example, longer, warmer summers have been linked to an increase in extreme lightning storms. Hotter surface temperatures can contribute to stronger updrafts which can potentially lead to more frequent and stronger lightning strikes. A 2024 study, Romps et al, showed that a 1% increase in surface temperature may lead to a 12% increase in the frequency of lightning strikes in the United States.
On top of this, an increase in the severity of wildfires unfortunately creates a positive feedback loop. By releasing naturally sequestered carbon back into the atmosphere, wildfires exacerbate the greenhouse effect, therefore contributing to further climate change.
Understanding the risk and changing climate
It’s particularly difficult to model wildfire risk in current insurance-industry catastrophe models or risk-scoring tools, partly because of the large number of factors that influence their ignition and spread, which are changing all the time. For example, climate change and changes in land-use and the expansion of human development into land prone to wildfires changes both the risk of wildfires igniting and spreading into populated areas the potential risk of damage to property or loss of life.
There is data available however, that helps us to understand some of the changes in risk and the impact that a changing climate may be having.
The US is particularly data rich when it comes to wildfires, enabling experts to discern trends about the number and severity of wildfires. Information gathered by the National Interagency Fire Center shows that between 2000 and 2022, the total number of wildfires across the United States decreased, but the area burned by wildfires grew, increasing the chance of a fire spreading into populated areas. Notably, data from the National Interagency Fire Center shows a statistically significant upward trend in the number of structures burned by wildfires between 2000 and 2022).
Data is somewhat harder to collate in Europe, in part because of the numerous national borders. But 2023 is proving to be one of their worst wildfire seasons for Spain and Greece, according to the European Forest Fire Information System. While the data shows a statistically significant decrease in the number of European wildfires between 2000 and present day – likely because of the increasing success of fire-suppression efforts, there has been a slight increase in the average size of wildfires recorded.
Although the frequency of wildfires in many parts of the world appears to be relatively stable or even decreasing – likely owing, in part, to improved suppression techniques - the damage caused by wildfires appears to be increasing, as the exposure changes and urban and developed areas – and human life - come under greater risk.
The impact of wildfires has likely been worsened by human actions, like igniting fires either accidentally or deliberately, and by contribution to climate change, according to the 2023 Global Fires Report.
The full extent of the impact of climate change on the triggers for wildfires also is not yet fully understood. But it is very likely that as surface temperatures increase, the risk of wildfires will increase.
As stated in the IPCC’s 2022 Assessment Report: “Projections for increased severity of future drought and heatwaves may lead to an increased frequency of wildfires…there is high confidence that fire weather conditions will become more frequent at higher levels of global warming in some regions.”
One of the current difficulties, however, is predicting exactly where those regions might be. While we have some understanding of areas that currently are more prone to wildfire risk, it’s clear that we must continue to monitor and understand the changing nature of the threat of, and exposure to, wildfires in the months and years to come, in order to help assess, manage and prepare for this peril.
