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Wildfires occur every summer, but they have been particularly deadly this year. Why are they so devastating?Allianz SE
A series of devastating wildfires in Portugal have killed 64 people since June. In 2016, Canada had its worst fires since 1958, and the deadliest wildfires in the history of California raced across the forests and the vineyards of the Napa Valley this October. More than 5,700 buildings have been destroyed, 213,000 acres of land scorched and 41 people have died so far.
And the fires still rage. On the Iberian Peninsula, central and northern Portugal and northern Spain are in the grip of an immense wildfire with more than 250 fire sources. In California, the fires were still described as an “inferno” in mid-October.
Wildfires burn regularly in most of these regions, so why have they been so devastating this year? A decade of drought, followed by torrential rains last winter has created extreme conditions. Climate change may also be exacerbating the problem.
“While the causes in California are still under investigation, we know that abundant dried vegetation and seasonal wind patterns helped fires spread quickly,” says Markus Stowasser, head of natural catastrophe research and development at Allianz Reinsurance. “After a decade of drought, the fuel levels – dry brush and grasses – across California are exceptionally high,” he explains. “Snow and torrential rain last winter helped break that drought, but also created more vegetation that, over the past six months, has led to even more fuel.”
The “Diablo” winds, typical for this time of the year, made matters worse: “The Diablo winds blow from northeast to southwest over California’s mountain ranges and down through the valleys and coastal regions. These downslope winds can quickly whip up a fire and carry burning embers to the next neighborhood or patch of woodland, creating corridors of fire,” says Stowasser.
In Portugal and Spain, the situation was different. “The entire Mediterranean area was very dry this year. Just take the southern Portuguese town of Faro, which last saw rain on May 12. Most of the region is bone-dry after the hot summer,” he says. While Portuguese officials believe the fires were started deliberately, weather on the Atlantic Ocean hasn’t helped: The fires are being fanned by strong winds of ex-Hurricane Ophelia on its way to Ireland.
The risk of any individual wildfire comes from a combination of temperature, wind, relative humidity, rainfall and dry biomass. These factors can be affected by changes in climate and weather patterns, such as “El Niño”. El Niño is a strong cycle of warm and cold temperatures on the surface of the Pacific Ocean, which in turn has a global effect on weather patterns.
Future climate scenarios foresee an increase in drought periods in the Mediterranean and, consequently, the worsening of fire hazard conditions. This may mean more frequent fires as well as greater areas of devastation. A recent publication of the EU Joint Research Center projects a significant increase in burnt area towards the end of the century on the Iberian Peninsula due to climate change.
Linking climate change to a particular catastrophic event is difficult, but the impact on plants and forests is clear. “Plants and trees are more sensitive to temperature rises, droughts and extreme weather events resulting from climate change than buildings,” says Jonathan Meagher, expert at natural catastrophe research and development at Allianz Reinsurance. “The increase in the number of forest fires in the high northern latitudes, like we saw last year in Canada, is an example of how the impact of climate change is being felt.”
Fire like the ones in California and Portugal are on the rise and Allianz is aware of the trend. “To understand the potential impacts of climate change, the Allianz Re team of experts uses climate models to build insurance risk models,” says Stowasser. “This is how we have, for example, investigated the impact of climate change on crop yields in Brazil.”
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