The fires in Los Angeles have already claimed dozens of lives, destroyed thousands of homes, and led to evacuation orders for hundreds of thousands of people. Economic damage is expected to be up to one hundred and fifty billion dollars. Daniel Soyen is a climate scientist at the University of California, Los Angeles and the University of California for Agriculture and Natural Resources who study harsh weather events and its relationship to climate change. I and I recently spoken on the phone. Our conversation, which was edited for length and clarity, below. In this, we discuss what really caused these fires to get out of control, how he tries to connect the role that climate change in natural disasters, and how the Los Angeles region has become vulnerable to disaster.
What makes these fires unique other than the damage they caused?
I think the huge range of damage in terms of the number of missing structures and economic losses is the most out of it. However, there are other aspects of a comprehensive position that are very different from anything we have seen before.
Let’s start with what is unusual, because I think this is useful for preparing the theater. It is not customary for the strong dry winds to occur in the mountains and valleys near Los Angeles in January. This particular event was significantly strong and stretched across the high and low -population areas of the usual. But if you are going to choose a year when you expect to see a strong dry wind, it will be now.
These are the winds of Santa Anna that you are talking about?
Yes, this is Santa Anna. This was somewhat different from the traditional Santa Anna event because it was driven by a slightly low decline in a slightly different spot. This is partly the reason that the wind comes from the north more than the east, and also why it was stronger than usual and reached the deepest in the valleys more than usual. But if you can think about it as Santa Anna or Santa Anna centenary, this is the same general idea. We only see strong winds every five, ten years, or so. Therefore, it is sure to note for sure, but it is far from unprecedented in itself.
Nevertheless, pre -conditions were very strange, as the unprecedented border – especially how dry conditions were. This is mainly estimated by looking at the amount of rain or not falling in the Los Angeles region or San Diego. What we find is that this is now either the beginning of drought or the second regret for the season registered throughout southern California, and it dates back to a hundred years. In modern history, this was not dry late in the virtual rainy season.
This is something that already paves this stage for these fires, because these same winds had occurred, for example, one inch or rain until now in the season, even if it is less than average, it is still good. If this happens, we will not see the fires that we see now. We will not have these dry explosive plants. He has not mainly grabbed Los Angeles since last spring – in many areas, about ten inches or less, which is not important from the perspective of wildfire.
Moreover, the inner parts of southern California – mountains, high plateaus and desert areas – stand out in their hottest summer. Los Angeles was not clear. After that, in early September, Los Angeles and the entire Los Angeles basin did not face a heat wave in standard destruction. This was actually associated with the outbreak of the main wildfires at the time, if you remember, in early September. Several structures were destroyed. It has remained unusually warm and the rains have never been long since. This is the real anomaly here, with winds a type of second degree anomalies.
Anyone can understand why it is easy to burn dry branches. But is this a very simplified way to think about the reason for the droughts of fires that can go out of control? Is there another level that is dangerous?
There are different levels, although I think the basic intuition makes you a good part of the road to there. Imagine an attempt to light a wet record of the shooting. This will not happen. There is this dual key, where if the vegetable cover is very wet, you cannot get combustion at all. There will be no flame. You light up matching and you will flow. You cannot start the camp fire.
Then there is another layer of dryness, as wood may not be moist, but also not especially dry. It is somewhere in the middle. And if you are very good at starting the camp, you may have this wood with some pre -heating, right? So, if you get some branches and some grass, the wood will eventually be shed because the flame under it is somewhat dry enough.
But there is also another level of dehydration where the vegetation is very acceptable to the spark. Not only does it make it more vulnerable to flammation in the first place, but it also greatly increases the actual density of subsequent combustion or fire. And through severity, I literally mean the amount of thermal energy it comes out. This is very important because not only dictates how intensity of fire and the number of damages that can cause it to the site but also affects the extent of the spread of these fires. The more the fire in general, the more possible spreading. Also, it increases the tendency of the fire to start generating its translated weather conditions that can lead to self -heating.
So there are these self -reinforcement comments, and the evil cycle. The vegetation can be very wet so that it cannot be burned at all, and in this case the threat of wild fires is approaching, right? After that, there is this other condition where it is sufficiently dry to burn, but it may not be burned intensively or very easily. After that, there is what is known as the dry vegetation, which will be mainly burned when the hat decreases and burns with great intensity, which facilitates all these successive positive feedback in terms of extremist and strange fire, which of course doubles if you suffer from the winds of the hurricane forces that operate on This fuel is very dry, as we did this week.
I saw you remembering something called “thirst in the atmosphere”, but it was not sure of what it means. Is this related to what you are talking about?
It is, the main relationship between increasing the risk of fires in the wildfire and climate change actually through this process itself, drought or dry vegetation itself, which of course becomes what becomes fuel in the forests. By definition, wild fires are a fire that burns plants. There are really two ways to dry the vegetation very quickly. One of them is, on the side of the width, no delivery of any water. In other words, if there is a lack of rain or snow, and the lack of rain, the soil becomes dry and the plants do not really have water to work with them in the first place.
There is also another way, even if there is a lot of rain, but if there is a surplus of evaporation and scandal – the drip is the negative part of the process and the conversion is part of the process that occurs when the water passes through living plants and comes out of menstruation in the leaves – There is something known as the Erdogy demand in the atmosphere. This is the artistic term for thirst, and mainly represents the inclination of air to extract water or water evaporation from surfaces or from plants. Surface surfaces can mean water surfaces, or the soil can be. The soil usually has at least some water, so the water that can evaporate, and will be evaporated at an increasing rate as the increased evaporation or thirst.
