What is behind the ‘unprecedented’ wildfires in California


Monstrous fires ravaging California killed 19 people, destroyed at least 4,000 structures and burned more than 12,500 square kilometers (more than double the area of ​​Prince Edward Island), breaking records as the worst fire season in the history of the State.”This is an unprecedented event,” said Noah Diffenbaugh, professor and senior researcher at Stanford University in California, who has studied the risk of fire in California. “We now have the largest wildfire in state history, as well as the third and fourth largest and five in the Top 10.”

He said they all started within the past three and a half weeks. The North Complex fire in northern California, which erupted on August 17 as a result of lightning, became the largest wildland fire in state history.

So what is behind this disaster?

Diffenbaugh said there were several contributors behind any individual fire, including the ignition of lightning or humans and the availability of dry fuel to fuel the flames.

But research over the past 15 years shows that climate change has dramatically magnified the risk of many conditions that help wildfires ignite and spread.

“We now have very strong evidence from those years of research that global warming is, in fact, increasing the likelihood of unprecedented extremes,” Diffenbaugh said.

In one published study in the journal Environmental Research Letters in August, Diffenbaugh and colleagues reported that the number of high fire risk days in California had doubled since the early 1980s, as climate change increased average temperatures by about 1 ° C and fall precipitation decreased by 30%. . Higher temperatures result in earlier snowmelt, a longer fire season and drier vegetation, especially in August and September.

This higher risk has helped increase the area burned in the western part of the United States tenfold over the past four decades, Diffenbaugh said.

Not only are fires more frequent, but they grow faster, he said.

“The brave men and women on the ground fighting these fires describe an unprecedented rate of spread in their years of experience,” he said, noting that the record-breaking fire at the North Complex has traveled 32 kilometers in one night.

WATCH | Wildfires devastate parts of the western United States:

More than 200 wildfires ravaging the western United States have killed at least eight people and caused catastrophic damage. 1:45

Research also suggests that this year’s new records will soon be broken by even more extreme wildfire seasons.

“If global warming continues on its current course, we will most likely experience a dramatic intensification – doubling or even tripling the frequency of occurrence of these extreme forest fire weather,” Diffenbaugh said.

Western Canada also faces a fiery future

These conditions are not unique to California, as devastating wildfires are also burning in Oregon and Washington state.

“We have a lot of evidence that this global warming increases the risk not only in California and the western United States, but also in western Canada,” Diffenbaugh said.

Western Canada has experienced a slow wildfire season so far this year after a few record seasons in recent years, including one whose destructiveness has been directly linked to climate change.

However, after more than 70 forest fires erupted in southern British Columbia for two days in August, officials warned that prolonged hot, dry weather could lead to more, and fire bans have been imposed across a wide swath of Alberta.

Helicopters drop buckets of water over a wildfire in Squamish, British Columbia, in April. On average, forest fires in Canada burn 2.5 million hectares per year, double the 1970s average, mainly in British Columbia and Alberta. (Ben Nelms / CBC)

Simon Donner, climatologist and professor of geography at the University of British Columbia in Vancouver, noted that in fact, Canada is heating up at about double the global average rate. “And that means more extreme heat and… more extreme fiery weather conditions. ”

On average, forest fires in Canada burn 2.5 million hectares per year (almost half the area of ​​Nova Scotia) – double the 1970s average. British Columbia and the Alberta were bear the brunt of this increase, according to Environment and Climate Change Canada.

Natural Resources Canada estimate the cost of forest fire management has grown by about $ 120 million per decade since 1970, at an annual cost of up to $ 1 billion in recent years.

How scientists are making a direct link to climate change

More as climate change increases the risk factors for extreme fires, is it directly responsible for the destructiveness of fires in California at this time?

It may take a few weeks to determine, using a scientific technique called ” science of event attribution.“It uses modeling to determine the likelihood of a given event with or without human-caused climate change.

Donner said this type of analysis was not possible 20 years ago, but it can now be completed in days or weeks.

“Considering the advances actually made in computer modeling and partly just the speed of computers, this work can be done faster and faster,” he said.

The technique recently showed that climate change:

WATCH | The San Francisco sky turns orange due to forest fires:

Locals are capturing video along the San Francisco-Oakland Bay Bridge as the city sky is blanketed in smog and debris from wildfires across the state. 0:45

How to reduce the risk

So what can be done to reduce the increasing destruction caused by forest fires in Canada and the United States?

Researchers recognize that the climate is not the only factor and that other risks can be reduced.

For example, suppressing too many small fires can allow fuel to build up, resulting in larger fires, so techniques such as controlled burns and less aggressive fire suppression in some areas can help.

Donner said how responsible people are when they are in the forest (humans cause 55% of fires in Canada) and land use planning, such as the choice of proximity to forest buildings, also play a role.

People can adapt to a higher fire risk in other ways as well, such as building houses with more fire resistant materials and keeping flammable materials away from their homes.

But Donner said reducing climate change was essential.

“We must do all we can to reduce greenhouse gas emissions,” he said. “It will continue to heat up until we stop emitting greenhouse gases. And so it will continue to get worse. ”

Diffenbaugh said that given the current strain on California’s emergency response system, we are clearly not adapted to the global warming that has already occurred.

He added: “To become resilient, we will have to catch up with the climate change we are already living with and get ahead of future climate change.”

WATCH | Scorching forest fires ravage parts of California:

Thousands of firefighters are battling out of control fires on many fronts, forcing emergency rescues and power cuts 1:11


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