 Towards the end of 2019, for months, fires ravaged California, burning through more than a quarter million acres of land. Before the embers were even put out, PG&E, California's largest utility provider, was in the spotlight for the role in these catastrophes. On the verge of bankruptcy, and with growing calls for a public takeover, it's worth asking, who's at fault for these fires? The reckless utility providers, the ever-warming climate, or even the people whose homes burned in the fire's path? Well, it's all of the above. Let's talk about that. California's Mediterranean climate keeps force without rainfall for months at a time. Dry summers tend to lead to wet winters, but the interval between them is prime time for fire season. California's wildfires aren't anything new. They go back as far as the history of bucks. Our furthest detailed accounts show that in the 1920s, fires burned millions of acres of land across California, and evidence points to fires being involved in California's natural ecosystem for hundreds of thousands of years by clearing out dead vegetation and making way for new trees. In fact, the ecosystem has even adapted to these frequent fires. In northern California, redwoods sport fire-resistant bark that shields them from intense blazes, and some tree saplings across southern California have fire-activated seeds that need to fire through the seeds to germinate and grow. It might come as a surprise, but California's wildfires have actually been becoming less frequent for decades. The last decade saw more than a third fewer forest fires than in the 1970s. But the trade-off here is that while these fires are becoming less common, they're also becoming much larger. Comparing 2018 to the early 2000s, despite fewer fires taking place, the total area of land burned went up by a quarter. In the state's largest fires, the ones that burned more than 300 acres of land each have seen their average sizes nearly tripled in that same time. What would have been a handful of small localized fires a few decades ago now results in megafires, and these fires have been raging across California. But what's caused these fires to grow out of control? An obvious answer is the climate. As it changes, California is exposed to higher temperatures, making it more prone to droughts. This leads to less water being retained by the ground and in the trees, which could act as slow as fires advance. The latest research shows that climate change has doubled the area of forest burned in the western United States in recent years. But for a fire to start, it needs a spark, and the vast majority are caused by people, not by nature. At the center of the California fire debate has been PG&E, California's largest utility company that provides gas and electricity for 16 million of California's 40 million people, including myself. That's about 40% of the state, and in providing power to those 16 million people, they directly cause more than 1500 wildfires in the last six years. On one hand, that's only about 3% of the fires California experienced in that timeframe. But not all fires are created equally. Of the seven largest fires to ever occur in California, three were caused by utility companies, including the deadliest fire in California's history. And PG&E might be criminally negligent. In 2017, PG&E estimated that the life expectancy of their high-voltage cables was 65 years, but the average of cables in use was 68 years, and some topped 100. This means that some cables were carrying more than 300,000 volts of electricity and were old enough to have provided power to Theodore Roosevelt. Lawsuits from the victims of recent fires totaling billions led to PG&E declaring bankruptcy just last week. But at the same time, are these fires really the utility's fault? Sure, they own the downed lines that cause the fires, but why are lines stretching deeper into force than ever before? There's another cause for the rapid rise in wildfire destruction, one that most people don't talk about, and it's the people that live in the fires path. California is the most populous state in the nation, with over 40 million people. Today, one in eight Americans call California home. And as California's population has swelled, it's leaked out of its urban confines along the coast and into California's inland forests. As communities encroach on historically uninhabited wilderness, the line between nature and society blurs. As utility companies are forced to provide electricity to these communities, there's been an explosion in the number of power lines in forested areas. Put simply, the more people living out in the forest, the more deadly, and also the more likely it is for these wildfires to occur. And on top of all of this, a century of fire suppression policies where the government quickly put out any and every fire they could, led to forests becoming filled with dead trees that would normally be cleared out in periodic fires. Now, decades of dead trees act as the kindling for the recent mega fires. And you remember those trees with fire resistant bark we talked about at the start of the video? Well, they can survive normal fires, but with all this extra kindling, the fires have been burning hotter, killing even the most fire resistant trees. In recent years, all these factors have played a role in exacerbating California's wildfires, causing the largest and deadliest fires in their history. The fires are complex, and a result of societal choices, and as a result, there's no one simple cause or solution. On top of all of this, the fires can have huge variability. Without changing much, last year saw a 90% decrease in acreage burned, mostly just because it was a wetter year. If there's one thing you learned from this video, it's that the wildfires are complex and have a lot of causes, so they probably aren't going anywhere. So if you live in California, buy some fire insurance. Don't forget to like and subscribe, and I'll see you next time.