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Kat Kerlin: Amy, every year our just seem to get worse. 

Amy Quinton: Well, that was certainly the case this summer. Another punishing round of record-breaking wildfires. 

Kat Kerlin: This time, wildfires burned the largest amount of land in California's recorded history. And a new “largest fire ever.” 

Amy Quinton: So, for those of you who may not live in California, here's what happened. Lightning strikes touched off hundreds of fires, at least hundreds of fires. And it devoured more than a million acres of land in one week alone. It overwhelmed firefighting forces, particularly with COVID limitations on crew size. 

Kat Kerlin: With incredibly hot and dry conditions, those fires joined with each other, creating these tremendous fire complexes, spewing smoke and ash across the entire state. 

News Clips: Several dangerous fires burning across southern California in stifling hot and dry conditions. 

News Clips: Smoke to where you can't see in front of you. Fire right on the road. The inside of your vehicle would heat up 30, 50 degrees. 

News Clips: The whole thing was engulfed. It was just a ball of flames. 

News Clips: Smoke filled skies in Los Angeles. Clouds in San Francisco cast a red glow on the city. 

News Clips: We're not even really at the peak of wildfire season in California. 

News Clips: Nine of the top ten biggest fires in state history have happened in the last decade. 

News Clips: They've destroyed whole communities. It doesn't seem quite adequate to call them forest fires anymore. 

Kat Kerlin: All of this makes you wonder if we're underestimating the magnitude and speed of these disastrous, devastating events, which have climate change's stamp all over it. 

Amy Quinton: So why do we say it's climate change? Well, record breaking temperatures for one California summers are now two and a half degrees warmer than they were in the 1970s. Kat, this year L.A. County hit 121 degrees. That's the highest ever. And Death Valley hit 130. Did you read that? It's the highest temperature reliably recorded on Earth. 

Kat Kerlin: Those warming temperatures dried out vegetation. And the number of extreme wildfire days has more than doubled since the early 1980s. And a that in our northern coastal ranges between Lake Berryessa and the Klamath Mountains, severe burns have increased 10 percent per decade since the 80s. 

Amy Quinton: That's sounding more and more like climate change. You know, California this summer essentially had a black summer. 

Kat Kerlin: Quite literally if you consider the smoke. 

Amy Quinton: But do you remember that though, that “Black Summer” is what Australians called their last summer of wildfires? By the time it was over, 33 people died, 3,000 homes were lost, and more than 46 million acres burned. That's an area nearly half the size of California. 

Kat Kerlin: Black Summer might seem like a blip in our collective memory now, given what's happened this summer or this year, but it shouldn't be. 

Malcolm North: I think it's very likely that . 

Amy Quinton: That's Malcolm North, a UC ����ԭ�� forest ecologist. 

Malcolm North: There's just no way around the fact that sometimes everything lines up and at least in Australia it appears to have been some of the hottest, driest conditions they've had in the last 50 to 100 years. 

Amy Quinton: We've seen our share of wildfire disasters here in California, too, not just this year, but the 2017 Northern California wildfires burned down entire neighborhoods of Santa Rosa, killing dozens of people. 

Kat Kerlin: Then in 2018, it got worse. High winds, unseasonably dry conditions and one spark from a power line was all it took to lead to the deadliest fire in the state's history. The Camp Fire, which killed 85 people. 

Amy Quinton: And Malcolm says climate change will bring more destructive wildfires to California. 

Malcolm North: We're going to have not just places like Paradise burn up, but unfortunately, we're probably going to see other places get incinerated as well on a much broader scale. 

Amy Quinton: Landscapes will change. We’ll lose some forests and the loss of life and property Australia had will pale in comparison to the casualties we might experience. 

Malcolm North: We have certainly, if anything, even more of a propensity for it. Australia, I think in the entire country only has 20 or 30 million people as we have 40 million in an area that's like one tenth or one eighth of the size of Australia. It's a matter of time. 

Unfold Theme: Climate models all agree that temperatures are going to increase. It's going to be hotter. It's going to be drier. Fires going to burn more frequently. Maybe this is never going to be the way it was again. We need to come up with ways to literally pull CO2 out of the atmosphere. How are we going to work together to solve a challenge like climate change? 

Amy Quinton: Coming to you from our closet studios as we shelter in place across the Sacramento region, this is Unfold, a UC ����ԭ�� podcast that breaks down complicated problems and discusses solutions. This week, we unfold wildfires in a changing climate. I'm Amy Quinton. 

Kat Kerlin: And I'm Kat Kerlin. 

Amy Quinton:  Kat, the first thing Malcolm said was that California doesn't just have one wildfire problem. We have several different kinds of wildfire problems. 

Kat Kerlin: Yeah, how they burn, how destructive or severe they are often depend on their environment or habitat. 

Amy Quinton: So probably everybody in northern California is familiar with our big forest fires. Our conifer forests, which historically relied on frequent fire, have become dense with trees. It's a result of decades of just putting out every fire. And all those trees and brush are ready to burn when wildfires strike. And it's a scary thought considering we have 33 million acres of forest in this state. 

Kat Kerlin: There are other types of wildfires, too, and some of the most destructive fires, where there's little you can do to stop it, take place in and oak woodland ecosystems. 

Amy Quinton: And chaparral is a type of shrubland where you'll find really drought tolerant plants with hard evergreen leaves and oak woodlands are lower elevation areas dominated by oak trees. 

Kat Kerlin: Fires in chaparral are often really hard to fight, especially if they're driven by Santa Ana winds. 

Amy Quinton: But now Malcolm says, we're seeing these monstrous wind-driven fires happen further north. 

Malcolm North: L.A. in the Southern California's been dealing with those for a few decades. But the fact that it's moved up into central and even kind of Northern California, that's something which is very recent and very disturbing. 

Amy Quinton: Malcolm says the problem isn't so much the winds, but conditions on the ground when the winds hit. 

Malcolm North: Most people would say, and I would agree, shifts in the climate are making these extreme wind events occur when normally you would have had wet fuels that can't catch because you've had rainfall. But if you notice, a lot of these big fires are happening in October, November, even December with the Camp Fire. That would not have happened very much in the past because everything would have been well soaked by rain at that point. 

Kat Kerlin: It's easy to get depressed by all this, but there are solutions. 

Amy Quinton: Yeah, Malcolm suggested alcohol. 

Kat Kerlin: No, really. 

Amy Quinton: Okay, well, before we get to those solutions, let's look at ways UC ����ԭ�� researchers are first trying to understand what's happening to our landscapes and second, how to manage it going forward. 

Amy Quinton: Derek Young, a forest ecologist at UC ����ԭ��, is taking me deep into the woods. 

Derek Young:  We're within the footprint of the American River fire, which burned in 2008 on the American River District of the Tahoe National Forest. 

Amy Quinton: That fire burned hot, flames engulfing the tops of the pine trees, what's called a crown or canopy fire. 

Derek Young: We're in a severely burned patch where almost all of the trees that were here before the fire have died and it's mostly a shrub field now. 

Amy Quinton: The area is choked with shrubs. We can barely push through it. It's full of red bark Manzanita and this godawful plant called Whitethorn Ceanothus. I'm sure butterflies love it, but I am not a fan of its long thorns. And I can accurately say I bled for this story. Derek says after a severe fire like this one, it can be impossible for conifer trees to naturally regrow. So, forest managers typically replant trees. 

Derek Young: Very few seeds survive in the soil from one year to the next, and especially after a fire. So, they rely on seeds to disperse from surviving trees nearby. And when you don't have any nearby, you don't get very much regeneration naturally. 

Amy Quinton: And while it's common to have some patches of forest burn severely with any fire, Derek says areas of forest that are severely burned are growing and both size and number. But to really get an understanding of how our forests are changing as a result of fire, he needs to get a bird's eye view. 

Derek Young: Ok, so powering on the drone. 

Amy Quinton: Derek is launching a Phantom 4 about 300 feet in the air. 

Derek Young: Ok, it's ready. Here we go. 

Amy Quinton: The drone will fly over almost 200 acres, capturing three-dimensional photos every two seconds. 

Derek Young: We'll use the drone data to capture the structure of forest stands after a wildfire and the density and spatial arrangement of the surviving trees. Because then we'll be able to use that to help us predict and understand the patterns of natural forest recovery after a fire. 

Amy Quinton: Understanding those patterns can also help determine how best to replant trees. Without the drone, ecologist and professor Andrew Latimer says getting this amount of data might take 10 years to map. He says with climate change, we don't have that kind of time, if we want forests to remain forests. 

Andrew Latimer: As the landscape gets more arid, those landscapes will shift from tree- dominated to shrub-dominated or grass dominated. And so what we're seeing these fires do is essentially press fast forward on the process. 

Amy Quinton: Scientists call these habitat shifts “type conversion,” and it's already happening in California. 

Andrew Latimer: That's a really hard thing. I mean, it's especially hard if it's your own backyard and you fear or you realize that maybe this is never going to be the way it was again. And I think a lot of people are starting to face that in some areas, especially areas that are kind of like at a transition zone at the edge of the forest. And that's something that, you know, we're wrestling with as scientists. And land managers are wrestling with as well because it's really hard to give up on a site that you thought should be forest, even if the projections for climate change suggest you shouldn't have trees, it really won't support trees there anymore. 

Amy Quinton: So Kat, I think that Andrew described the worst situation of what could happen to some of our forests - that we'll lose them. But we can make our forests more . Andrew and Derek are looking at the best ways to plant trees, as well as what species to plant in order to restore a forest after a wildfire. 

Kat Kerlin: What scientists have learned is that decades of planting trees in the same way, like rows of corn, doesn't work. 

Amy Quinton: Yeah, because pine trees are evenly spaced in straight lines. Here's what Malcolm said about that. 

Malcolm North: What we understand now about the fact is that you need . But if you put them all in a regular pattern like that, they are really susceptible to getting burned up when the next fires come through. And when pines are that close together and the crowns are down low to the ground, they don't just burn, they get vaporized. 

Amy Quinton: And Kat, I remember that this happened in the Rim Fire in 2013. There was an area of forest in the Stanislaus National Forest that had been replanted this way after a fire in 1987. So when the Rim Fire hit, all of those replanted trees were just incinerated. 

Kat Kerlin: That's why forests need to have a more natural spacing like what Malcolm described. Historically, fires from lightning strikes would sculpt forests, removing small trees and brush that could act as fuel. 

Amy Quinton: And prescribed fires, which are sometimes called controlled burns, are a solution to helping our forests under a changing climate. 

Kat Kerlin: