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November 01, 2017

Why are wildfires concentrated in the west?

'Infrequently Asked Questions' seeks the answer

California's forests have been particularly hard-hit with wildfires this year, with costs of the Northern California fires topping more than $3 billion in damages--not to mention the death of dozens. 

Big-picture, though, it might make some wonder: Why are so many dangerous forest wildfires seemingly contained to the West Coast? These are "Penn's Woods," after all, with no shortage of hot days.

Curious, we reached out to Stephen Mason, a researcher in Drexel University's Department of Biodiversity, Earth and Environmental Science whose studies focus on the New Jersey Pine Barrens and the effects of climate change.

To ask the umbrella question: Why does it seem like so many forest fires are concentrated in the west? We seldom hear about a major East Coast fire. 

  • The world is full of questions we all want answers to, but are either too embarrassed, time-crunched or intimidated to actually ask. With Infrequently Asked Questions, we set out to answer those shared curiosities. Have a question you want answered? Send an email to, and we’ll find an expert who can give you the answer you’re craving.

Wildfires happen everywhere, globally. But when talking about the U.S., the West Coast is getting a lot more attention for a few reasons. Actually, a lot of reasons. The first thing coming to mind is that the West Coast has a different climate than the East Coast and Great Plains. And we have wildfires [on the East Coast], too. 

The West Coast, they're actually getting hit harder by climate change than the rest of the U.S., and people might be familiar with it because they're getting a lot of droughts. With that drought, you're having drier areas and wildfires will become more frequent and intense and even longer. On top of that, because there's so much drought, there are a lot of trees dying because they're not getting enough water. And dead trees burn easier and faster. 

Why is that?

It's drier wood. It's a lot harder to put a green leaf on fire than a brown leaf on fire. And the West Coast--again, there's a lot of acres of forest out there. 

... And the other big thing is, and this is on the East Coast too, but every time a fire gets started it's put out immediately. That actually, depending whose perspective it is, could be bad. When a wildfire comes through, it eliminates leaf litter--duff. But since they're put out quickly, duff builds up. So when a wildfire does come through, it picks up all the leaf litter and makes them worse.

That's counter-intuitive. By stopping a fire you're causing other fires?

For the ecosystem, Smokey the Bear says, "Only You Can Prevent Wildfires," but we need a wildfire to get rid of the fuel load. But it's leaf litter that's accumulating. One way to prevent the fires, on the East Coast more than the West Coast, with a fire service, is to light a prescribed burn – to make sure it never gets out of control.

But the West Coast, there's so much land, you can't do a prescribed burn everywhere. Then you have all this accumulation of leaf litter because fires are put out as fast as possible. 

So, these fires do happen on this side of the U.S.?

Wildfires happen everywhere, but the West Coast gets more attention because it's bigger, hotter and lasts a long time. And when I do my research about the Jersey Pine Barrens--relatively local to Philadelphia--there's a relatively big fire that happened this summer of 3,500 acres in the Wharton State Forest. That's a bigger one recently. And there are a lot of habitats that benefit from fires--they're needed for ecosystems, but with climate change, they're more frequent and hotter than they historically have been.

How much more frequent?

It depends on where you are in the world. One thing I could speak to, with New Jersey, it's said that historically wildfires were once every 20 years depending on where you are in the Pine Barrens. There's a place called the Pigmy Pines, where a wildfire burns every seven years--but because New Jersey is built-up and, even though the Pine Barrens is protected from development, there are still [houses] everywhere. The forest fire service does a good job of controlling wildfires, so at least in South Jersey, the wildfires have decreased because there are houses scattered all over, so it's easier to protect them.

I might've contradicted myself, but globally they're increasing in intensity and happening frequently.

Will wildfires push farther east as time goes on? Say, in the Appalachians? 

The East Coast is a different climate, and what's different about the Pennsylvania forests is they're mostly deciduous trees. So, every terrestrial area on the planet has had a wildfire at least once. Once every 200 years, or 20 years. Eventually, there will be a wildfire and it's a matter of how bad it is, intense it is, fast it is. We will see a wildfire in Pennsylvania at one point or another, but it's hard to say when because it's situational.

That's another thing about the Pine Barrens: they're coniferous forests with pine trees; habitats are a lot drier. Pennsylvania's forests are a wetter area.

When a wildfire does start, do we know the cause of how it happens? 

There are different ways to tell. My understanding is if there's a thunderstorm and a fire starts shortly after, chances are it's a lightning strike. Most wildfires happen from lightning strikes. And then you can find the center of where a fire started, a tree cut by a lightning strike. And other times it's a lit cigarette thrown into dry leaves, and it can start that way, too.