Are Wildfires Caused by Utilities or Climate Change? Yes

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Today, we hear from Adam Sobel, an atmospheric scientist and director of the Initiative on Extreme Weather and Climate at Columbia University. He previously helped explain Hurricane Dorian for The Times.

Now, he tackles wildfires:

As offshore winds are again forecast to bring hot, dry air to the woodlands of western California, and wildfires threaten for the second time in a couple of weeks, PG&E warns that it may shut down power again. If it didn’t do this, and the sparking of its wires resulted in awful fires as they did last year, would it be culpable?

Or would climate be the cause — and if so, can we blame human-induced global warming, or natural variability in the climate system that would occur anyway? Or is the real problem that people are now living in fire-prone places, where historically they didn’t, and where natural fires have been artificially suppressed, letting fuels build up?

The answer to all of these questions is yes.

[Read more about Smokey Bear and the question of personal responsibility in preventing wildfires.]

A fire needs a spark. If PG&E’s wires provide that, then the company is responsible, just as I would be if I started a fire with a tossed cigarette or an unattended campfire. Californians are right to try to hold PG&E accountable, and the evidence suggests that it has been poorly managed, deferring crucial maintenance for years.

At the same time, the fire wouldn’t spread so far and be so catastrophic if the weather weren’t right for it. And while the proximate causes of the National Weather Service’s fire weather watches and red flag warnings lie in the more or less random fluctuations of day-to-day weather, there is compelling evidence that global warming has increased the risk substantially. Heat dries out what scientists who study the problem clinically refer to as “fuel” — that is, trees and shrubs and such — so that they burn more quickly and easily.

[How PG&E ignored fire risks in pursuit of profit.]

Then again, tree rings show that there have been droughts even worse than those in the past century, and that fire has been a part of the natural history of California and the western United States for millenniums. So human greenhouse gas emissions are by no means solely to blame.

But they make the problem worse than it would otherwise be, since the natural climate variability is already a given, in exactly the same way that bad habits, like smoking, increase the risks of diseases that one would already stand some risk of getting due to bad luck alone.

The same goes for human fire suppression and real estate development in the “wildland-urban interface.” Yes, these are part of the problem too — maybe bigger parts than climate change, so far. But these factors are not mutually exclusive, and the warming influence will only grow with time.

[Here’s how Santa Ana winds shape wildfire season.]

This situation is not specific to fire, either. It’s generic to a wide range of increasing climate risks. Disasters happen when a geophysical hazard meets people. Floods, for example, occur not just because of storm surges or heavy rains, but also because of unwise development in flood plains, or failures of infrastructure, or both. And global warming always acts as an extra influence on top of natural variability that, in the short-term view, is often more important.

The important distinctions are ethical as much as they are scientific. Natural climate variability is out of human control. Building homes in dangerous places isn’t. Neither are poorly maintained electric power lines. Or continued uncontrolled carbon emissions.

[Read more about why the “worst of both worlds” is in the forecast for California.]

Here’s what else we’re following

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Fifty years ago, Native American activists from the Bay Area and beyond occupied Alcatraz Island.

They were protesting decades of mistreatment by a government they said had tried to erase their heritage by eliminating tribes and forcing assimilation, my colleague John Eligon reported. The occupation spurred a new wave of activism by indigenous people from across the continent.

So earlier this month, Native Americans from different tribes gathered in San Francisco for a canoe journey to Alcatraz to mark the anniversary.

The occasion was celebratory and defiant.

“We will not be forgotten,” Cortney Russell, of the Shxwhá:y Village in Canada, told the crowd on the shore.

Click through the visual story here.

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Jill Cowan grew up in Orange County, went to school at U.C. Berkeley and has reported all over the state, including the Bay Area, Bakersfield and Los Angeles — but she always wants to see more. Follow along here or on Twitter, @jillcowan.

California Today is edited by Julie Bloom, who grew up in Los Angeles and graduated from U.C. Berkeley.