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If you want to decarbonize concrete, it helps to understand the incredible scale of the problem.
To say that concrete poses a decarbonization challenge would be an understatement. Cement production alone is responsible for somewhere between 5 and 10% of global CO2 emissions [0], roughly two to four times more than aviation, a fact that even the construction industry is finally coming to grips with.
And yet the real problem with decarbonizing concrete isn’t the scale of its emissions, it’s the scale of concrete itself. There is simply a preposterous amount of the stuff. Contemplating concrete is like contemplating the universe — awesome, in the old God-fearing definition of the word.
Before we get into the jaw-dropping amount of concrete we produce every year, it’s worth briefly discussing how the stuff is made, and thus where its emissions come from.
Concrete is formed by mixing together cement (mostly calcium silicates), aggregates (such as sand and gravel), and water into a liquid slurry. The cement reacts with the water, forming a paste that binds the mixture into a single solid mass. Beyond concrete’s high strength and low cost, it’s these liquid beginnings that make concrete so useful. It can easily be formed into any shape and leveled with the help of gravity so you can walk on it or park a car 10 stories up on it. Essentially all modern concrete is also reinforced with steel bars, which provide tensile strength and arrest cracks.
So what about the emissions? Roughly 70-90% of the embodied carbon in concrete comes from manufacturing just the cement [1]. Partly this is because making cement is an energy-intensive process — limestone and clay are put into a kiln and heated around 2500 degrees Fahrenheit. But it’s also because the chemical reaction that turns the limestone into cement (known as calcination) releases CO₂ as a byproduct. Roughly 50-60% of cement’s carbon emissions are due to calcination [2], and thus wouldn’t be addressed by moving to less carbon-intensive electricity sources, like green hydrogen.
Now for the good stuff. Again, the most important thing to understand about concrete is the scale of its production. The world produces somewhere around 4.25 billion metric tons of cement annually (though estimates vary) [3], which works out to about 30 billion tons of concrete produced each year [4].
How much are 30 billion tons?
One way of looking at it is we produce around 4 metric tons, or just under 60 cubic feet (roughly a cube 4 feet on a side), of concrete for each person on the planet each year.
Another way of looking at it is to consider the total amount of mass, full stop, that civilization ingests each year. Estimates here vary quite a bit, but it seems to be in the neighborhood of 100 billion tons [5]. So of the total volume of material that gets extracted and used each year — including all mining, all oil drilling, all agriculture and tree harvesting — around 30% of it by mass goes toward making concrete. The amount of concrete produced each year exceeds the weight of all the biomass we use annually, and all the fossil fuels we use annually.
Total civilization annual material extraction, via Krausmann et al 2018. This is up to 2015, and has now exceeded over 90 Gt/year, with another ~8 Gt/year of recycled material.
Another way of looking at it is that the total mass of all plants on Earth is around 900 billion metric tons. So at current rates of production, it would take about 30 years to produce enough concrete to exceed all the Earth’s plant (dry) biomass.
Because humans have been producing concrete for a while, and because concrete tends to last a long time, we seem to be on the cusp of this happening. Elhacham et al 2020 estimate that total human-created mass (roughly half of which is concrete) reached the total weight of all Earth’s biomass sometime in 2020. Eyeballing their graph, concrete alone will exceed the total weight of all biomass sometime around 2040.
Anthropogenic mass vs biomass during the 20th century, via Elhacham et al 2020
In a pure mass-flow sense, human civilization is basically a machine for producing concrete and gravel (and to a lesser extent bricks and asphalt).
So civilization uses a lot of concrete. Where is it all going?
China, mostly. In recent history, China has been responsible for roughly half the world’s cement production, and by implication, concrete use [6]. The U.S., by comparison, only uses 2%, with Europe using another 5%.
Cement production by region, via Sanjuan et al 2020. Since cement production roughly tracks consumption (see here and here), we can also use this as a rough guide toward where concrete is used. Note that this gives yet another value for total global cement production of 4.65 Gt
Here’s another view from around 2010, showing what this has looked like over time (data after 2010 is a projection).
Cement consumption by region, via Altwair 2010
This gets summarized in the oft-repeated statistic that China used more cement in three years than the U.S. did in the entire 20th century.
But since China has a much larger population than the U.S., we can get a more intuitive understanding of this by looking at cement consumption per capita. Here’s per capita consumption sometime around 2015:
Per capita cement consumption by country, via Globbulk
We see that the official numbers from China make it a huge outlier in cement consumption, using around eight times as much per capita as the U.S. However, in per capita terms, some Middle Eastern countries exceed it. Saudi Arabia is higher, and Qatar, which is somewhere over 2,000 kg/capita, is so high it doesn’t even show up on the graph. It’s the combination of China’s huge population and its huge per-capita consumption that make it such an outlier in concrete production.
The official Chinese numbers are so huge, in fact, that some analysts suspect that they’re inflated, either by manipulating the data or by producing construction projects that don’t have actual demand (or both). The graph above also includes a more “realistic” estimate (which is still 3x as high as U.S. per-capita use).
What does all this concrete construction mean in practical terms? Well, China has somewhere around 50-60% of the floor space per capita as the U.S. does, or roughly as much living space per capita as most European countries [7]. This is the result of a massive trend toward urbanization over the last quarter century. Urbanization rates went from around 25% in 1990 to 60% in 2017, a period in which China’s population also increased by 250 million. In other words, in less than 30 years over 550 million moved into Chinese cities, and they all needed somewhere to live. By building enormous numbers of concrete high rises, in under 20 years China quintupled its urban residential floor space and doubled its residential floor space overall.
Residential floor space in China over time, via Pan 2020
Beyond China, we see high per capita rates of cement use in the rest of Southeast Asia, as well as the Middle East [8].
One reason you see this volume of concrete use in lower-income, urbanizing countries is that concrete construction is comparatively labor-intensive to produce. The materials for concrete are extremely cheap, and much of its cost in high-cost labor countries (such as the U.S.) is from the labor to produce it — building and setting up the formwork, laying out the reinforcing, placing the embeds, etc. If you’re a country with a lot of low-cost labor, this is a pretty good trade-off.
In addition to the current largest users of concrete, one trend to keep an eye on long-term is India’s concrete use. If India ever proceeds on a path of mass urbanization similar to China (as some folks speculate it will), we could see a massive uptick in global concrete output — India’s urbanization rate of 34% is around where China was in the late 1990s. A shift in India toward a per capita cement consumption more consistent with the rest of Southeast Asia (say around 600 kg/capita) would increase worldwide cement consumption by about 13%, and it does seem as if India’s cement use is trending upward.
By contrast, one thing clear from this data is that the U.S. actually uses an unusually low amount of concrete. Per capita, it uses as little as any other Western country, and far, far less than some — like, surprisingly, Belgium.
So we’ve seen where it gets used in the world. Can we go deeper and look at specifically what concrete is being used for?
This will vary significantly depending on the region and the local construction tradition. In the U.S., we have roughly the following breakdown (via the Portland Cement Association):
Overall, roughly half of our concrete gets used in buildings — about 26% goes into residential buildings, 2% in public buildings, and 16% into commercial buildings. The other half gets used for infrastructure — streets and highways, water conveyance and treatment tanks, etc. Because most construction in the U.S. is just one- or two-story buildings (mostly wood for residential buildings and steel for commercial ones), concrete in buildings is probably mostly going into foundations, slabs on grade, and concrete over metal deck, though there’s probably a substantial amount going into concrete masonry units as well.
But the U.S. has a somewhat unusual construction tradition, where the vast majority of our residential construction, both single-family homes and multifamily apartments, is built from light-framed wood. In other places, it's much more common to use concrete. For instance, the U.K. uses closer to 80% of its concrete for buildings, with most of that going toward the superstructure, the concrete frame that holds the building up. China, which has urbanized on the back of huge numbers of concrete residential high rises, probably devotes an even larger share of its concrete to residential construction.
Understanding how much concrete the world uses, and where it’s being used, is important if you want to use less of it.
The scale of the industry is particularly important to keep in mind. For instance, you often see enthusiasm for the idea of replacing concrete buildings with mass timber ones. But assuming you could substitute all the world’s concrete for an equal volume of wood [9], you’d need to more than triple the total annual volume of global wood harvested [10], which puts a somewhat different spin on the issue.
Most other materials would have emissions as bad or worse than concrete if they were used on the same scale.
Consider, for instance, railway ties. In the U.S., these are still largely made out of wood, but in many places they have been replaced with concrete ties. And some places are considering changing from concrete ties to plastic composite rail ties instead. It’s hard to know the exact embodied emissions without a lot of specific details about the materials and supply chains used, but can we ballpark how much a plastic tie uses compared to a concrete one?
Per the Inventory of Carbon and Energy database, concrete varies between 150 and 400 kg of embodied CO2 per cubic meter, depending on the properties of the mix, with an “average” value of about 250. Plastics mostly have embodied emissions of about 3-4 kg of CO2 per kg of plastic, or about 3,500 kg per cubic meter (assuming a density of about 1,000 kg per cubic meter). So per unit volume, plastic has somewhere around 10 times the embodied emissions of concrete.
We can also do a more direct comparison. Consider a beam spanning around 20 feet and supporting a vertical load of 21,000 pounds per linear foot. The lightest U.S. standard steel section that will span this distance is a W16x26, which weighs about 236 kg and will have embodied carbon emissions of around 354 kg.
A concrete beam of the same depth, supporting the same load and spanning the same distance, will be 10.5 inches wide by 16 inches deep, with three #10 steel bars running along the bottom. This beam will have about 190 kg of embodied emissions from the concrete, and about another 230 kg of embodied emissions from the steel rebar. This is about 20% more than the steel beam, but in the same ballpark — and over half the “concrete” emissions are actually due to the embedded reinforcing steel.
This is arguably a nonrepresentative example (most concrete, such as in columns or slabs, will have a much lower ratio of steel), but the basic logic holds: Concrete is unusual in its total volume of use, not how emissions-heavy it is as a material. Most material substitutes that aren’t wood, recycled materials, or industrial byproducts that can be had for “free” won’t necessarily be much better when used at the same scale. In some ways, it’s surprising that the carbon emissions from concrete are as low as they are.
Of course, this calculus is likely to change over time — as electricity sources change over to lower carbon ones, you’re likely to see the embodied emissions of materials drop along with it. And since cement releases CO2 as part of the chemical process of producing it, concrete will look increasingly worse compared to other materials over time.
One potential option is to find ways of changing the cement production process to be less carbon-intensive. The easiest option is to just replace manufactured Portland Cement with some other cementitious material. Industrial byproducts such as blast furnace slag, silica fume, and fly ash, often have cementitious properties and don’t have a “carbon penalty” (since they’d be produced regardless.) Materials like these can potentially eliminate large volumes of cement in a concrete mix, and they’re a key part of current low-carbon concrete strategies — even “normal” concrete mixes tend to utilize these to some degree. But the total volume of these materials is limited by the extent of various industrial processes. And for things like fly ash (which is a byproduct from coal plants) and slag (which is a byproduct from CO2-emitting blast furnaces), we can expect production to decline over time.
Another option is to take advantage of the fact that concrete will naturally absorb CO2 over time, a process known as carbonation. Even normal concrete will absorb roughly 30% of the CO2 emitted during the production process over the course of its life. Companies like Carbicrete, Carboncure, Carbonbuilt, and Solida all offer methods of concrete production that allow the concrete to absorb CO₂ during the production process, substantially reducing embodied emissions. Interestingly, these producers mostly claim that their concrete is actually cheaper than conventional concretes, which would obviously be a massive tailwind for the technology’s adoption.
It’s not obvious what the best path forward is for addressing concrete carbon emissions (like with most things, I suspect it’ll end up being a mix of different solutions), but understanding the parameters of the problem is necessary for solving it.
Note: A version of this article originally appeared in the author’s newsletter, Construction Physics, and has been repurposed for Heatmap.
[0] - This figure varies depending on the source. Chatham House provides a frequently cited estimate of 8%. We can also ballpark it — roughly 0.93 pounds of CO₂ gets emitted for each pound of cement produced, around 4.25 billion tons of cement are produced annually, which gets ~3.95 billion tons of CO₂, and total annual CO₂ emissions are in the neighborhood of 46 billion tons, getting us a bit less than 9%.
[1] - Per Circular Ecology, ~70-90% of emissions are from the cement production process, depending on the type of concrete and what the rest of the supply chain looks like.
[2] - This seems to vary depending on where the cement is being made — in Myanmar, for instance, it’s around 46%.
[3] - Another number where the sources often don’t agree with each other, see here, here, and here for estimates on annual cement production.
[4] - Concrete is roughly 10-15% cement by weight, depending on the strength of the mix, what other cementitious materials are being used, etc. An average value of 12.5% yields 34 billion tons, which we’ll knock down to account for other uses of cement (masonry mortar, grout, gypsum overlay, etc.) This roughly tracks with estimates from PCA (“4 tons of concrete produced each year for every person on Earth”), and from the now-defunct Cement Sustainability Initiative, which estimated 25 billion tons of concrete against 3.125 billion tons of cement in 2015.
[5] - See here, here, and here for an estimate of total civilization mass flow. This doesn’t (I believe) include waste byproducts, which can be substantial — for instance, it doesn’t include the ~46 billion tons of CO₂ emitted each year, or the 16 billion tons of mine tailings, or the 140 billion tons of agriculture byproducts (though this last number is difficult to verify and seems high).
[6] - We see something similar with cement as we do with other bulky, low-value materials, in that it's made in lots of distributed manufacturing facilities relatively close to where it’s used. See here for a map of cement plants in the U.S. around 2001, for instance.
[7] - For China’s total floor space, see here (most sources seem to agree with these numbers). For U.S. floor space, see my Every Building In America article. For per-capita living space in Europe, see here.
[8] - The often high rates of cement use by middle-income countries have led some folks to develop a U-shaped cement consumption theory of industrial development — that countries start out using a small amount of cement, use more as they get richer and build up their physical infrastructure, and then eventually transition to using lower volumes of cement again. The Globbulk paper spends considerable time debunking this.
[9] - It’s not actually obvious to me what the substitution ratio would be. In strength-governed cases, you’d need proportionally more timber than concrete, but in other cases (such as replacing concrete walls with light-framed stud walls), you’d probably use less. Obviously, you can’t substitute all concrete for wood, but you can probably switch out more than you think — there’s no reason you couldn’t use wood foundations instead of concrete ones in many cases, for instance.
[10] - 30 billion tons of concrete is roughly 12.5 billion cubic meters, and total annual wood products produced is currently around 5.5 billion cubic meters.
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Plus 3 more outstanding questions about this ongoing emergency.
As Los Angeles continued to battle multiple big blazes ripping through some of the most beloved (and expensive) areas of the city on Friday, a question lingered in the background: What caused the fires in the first place?
Though fires are less common in California during this time of the year, they aren’t unheard of. In early December 2017, power lines sparked the Thomas Fire near Ventura, California, which burned through to mid-January. At the time it was the largest fire in the state since at least the 1930s. Now it’s the ninth-largest. Although that fire was in a more rural area, it ignited for some of the same reasons we’re seeing fires this week.
Read on for everything we know so far about how the fires started.
Six major fires started during the Santa Ana wind event last week:
Officials are investigating the cause of the fires and have not made any public statements yet. Early eyewitness accounts suggest that the Eaton Fire may have started at the base of a transmission tower owned by Southern California Edison. So far, the company has maintained that an analysis of its equipment showed “no interruptions or electrical or operational anomalies until more than one hour after the reported start time of the fire.” A Washington Post investigation found that the Palisades Fire could have risen from the remnants of a fire that burned on New Year’s Eve and reignited.
On Thursday morning, Edward Nordskog, a retired fire investigator from the Los Angeles Sheriff’s Department, told me it was unlikely they had even begun looking into the root of the biggest and most destructive of the fires in the Pacific Palisades. “They don't start an investigation until it's safe to go into the area where the fire started, and it just hasn't been safe until probably today,” he said.
It can take years to determine the cause of a fire. Investigators did not pinpoint the cause of the Thomas Fire until March 2019, more than two years after it started.
But Nordskog doesn’t think it will take very long this time. It’s easier to narrow down the possibilities for an urban fire because there are typically both witnesses and surveillance footage, he told me. He said the most common causes of wildfires in Los Angeles are power lines and those started by unhoused people. They can also be caused by sparks from vehicles or equipment.
At more than 40,000 acres burned total, these fires are unlikely to make the charts for the largest in California history. But because they are burning in urban, densely populated, and expensive areas, they could be some of the most devastating. With an estimated 9,000 structures damaged as of Friday morning, the Eaton and Palisades fires are likely to make the list for most destructive wildfire events in the state.
And they will certainly be at the top for costliest. The Palisades Fire has already been declared a likely contender for the most expensive wildfire in U.S. history. It has destroyed more than 5,000 structures in some of the most expensive zip codes in the country. Between that and the Eaton Fire, Accuweather estimates the damages could reach $57 billion.
While we don’t know the root causes of the ignitions, several factors came together to create perfect fire conditions in Southern California this week.
First, there’s the Santa Ana winds, an annual phenomenon in Southern California, when very dry, high-pressure air gets trapped in the Great Basin and begins escaping westward through mountain passes to lower-pressure areas along the coast. Most of the time, the wind in Los Angeles blows eastward from the ocean, but during a Santa Ana event, it changes direction, picking up speed as it rushes toward the sea.
Jon Keeley, a research scientist with the US Geological Survey and an adjunct professor at the University of California, Los Angeles told me that Santa Ana winds typically blow at maybe 30 to 40 miles per hour, while the winds this week hit upwards of 60 to 70 miles per hour. “More severe than is normal, but not unique,” he said. “We had similar severe winds in 2017 with the Thomas Fire.”
Second, Southern California is currently in the midst of extreme drought. Winter is typically a rainier season, but Los Angeles has seen less than half an inch of rain since July. That means that all the shrubland vegetation in the area is bone-dry. Again, Keeley said, this was not usual, but not unique. Some years are drier than others.
These fires were also not a question of fuel management, Keeley told me. “The fuels are not really the issue in these big fires. It's the extreme winds,” he said. “You can do prescription burning in chaparral and have essentially no impact on Santa Ana wind-driven fires.” As far as he can tell, based on information from CalFire, the Eaton Fire started on an urban street.
While it’s likely that climate change played a role in amplifying the drought, it’s hard to say how big a factor it was. Patrick Brown, a climate scientist at the Breakthrough Institute and adjunct professor at Johns Hopkins University, published a long post on X outlining the factors contributing to the fires, including a chart of historic rainfall during the winter in Los Angeles that shows oscillations between wet and dry years over the past eight decades.
But climate change is expected to make dry years drier and wet years wetter, creating a “hydroclimate whiplash,” as Daniel Swain, a pre-eminent expert on climate change and weather in California puts it. In a thread on Bluesky, Swain wrote that “in 2024, Southern California experienced an exceptional episode of wet-to-dry hydroclimate whiplash.” Last year’s rainy winter fostered abundant plant growth, and the proceeding dryness primed the vegetation for fire.
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Editor’s note: This story was last update on Monday, January 13, at 10:00 a.m. ET.
On tough questioning from the Senate, LA’s fires, and EV leases
Current conditions: Odd weather has caused broccoli and cauliflower plants to come up far too early in the UK • Another blast of Arctic air is headed for the Midwest • An air quality alert has been issued in Los Angeles due to windblown dust and ash.
Firefighters in Los Angeles are scrambling to make progress against the ongoing wildfires there before dangerous winds return. The Palisades and Eaton fires have now been burning for almost a week, charring nearly 40,000 acres, damaging more than 12,000 structures, and leaving at least 24 people dead. They are 13% and 27% contained, respectively. Residents who lost their homes are desperately trying to find new properties to rent or buy in a tight market, with reports of intense bidding wars as landlords hike rents. The economic toll of this disaster is estimated to be between $135 billion and $150 billion. Red flag warnings are in effect today, with critical fire conditions and extreme wind gusts forecast through Wednesday.
Red fire retardant on pool furniture. Justin Sullivan/Getty Images
A few updates on the incoming administration: President-elect Donald Trump tapped Ed Russo to run an advisory environmental task force. Trump said Russo will oversee “initiatives to create great jobs and protect our natural resources, by following my policy of CLEAN AIR and CLEAN WATER. Together, we will achieve American Energy DOMINANCE, rebuild our Economy, and DRILL, BABY, DRILL.” Russo is a longtime Trump loyalist who served as an environmental consultant to the Trump Organization and wrote a book titled “Donald J. Trump: An Environmental Hero”.
Trump also announced his deputies for some key environmental and energy Cabinet positions over the weekend, including:
More than a dozen of Trump’s Cabinet nominees face Senate confirmation hearings this week. Doug Burgum, who is up for interior secretary, has a hearing before the Committee on Energy and Natural Resources tomorrow. Energy secretary nominee Chris Wright has one on Wednesday. EPA nominee Lee Zeldin has one with the Environment and Public Works Committee on Thursday.
Affordable EV leases are “the car market’s hottest deal,” according toThe Wall Street Journal. Car companies are changing the way they pitch EVs to buyers, offering short-term leases with low monthly payments. These deals are attractive to first-time EV shoppers who are still a little bit hesitant to commit, as well as people on a tighter budget. Roughly 45% of EV transactions at the end of 2024 were leases, much higher than the auto industry as a whole. And a provision in the Inflation Reduction Act means leased cars can more easily qualify for the government’s $7,500 EV tax credit. “The proliferation of lease deals has made EVs more accessible to buyers who couldn’t afford their higher sticker prices,” the Journal said. “For the automakers, it is helping get more EVs into customers’ hands after a choppy start for their electric-car operations.”
Wind power could overtake coal in Europe for electricity generation for the first time this year, according to the energy think tank Ember. At the end of 2024, wind power was closing in on coal, coming in at just 4% below the fossil fuel in power generation as the continent’s coal plants close. “That output gap could easily be made up over the course of 2025 by an increase in regional wind generation capacity or by higher average wind speeds at turbine level, or by some combination of both,” Reutersreported. Last year wind power accounted for 20% of electricity consumed in the EU, and the goal is to get that up to 50% by 2050. But as Electreknoted, the same problems plaguing projects in the U.S. – permitting delays and connection bottlenecks – are slowing things down. The EU accounts for 4.6% of global power sector emissions.
The World Health Organization’s European Centre for Environment and Health has issued a callout for “examples of interventions to protect and promote mental health in the face of climate change.” The group wants to take stock of these interventions so that it can identify gaps in mental health care and share some best practices. The callout is aimed at Europe only, but it is indicative of a growing awareness of how the worsening climate crisis is taking a toll on mental health worldwide.
“There’s a lot of finger-pointing going around, and I would just try to emphasize that this is a really complex problem. We have lots of different responsible parties. To me, what has happened requires more of a rethink than a blame game.” –Faith Kearns, a water and wildfire researcher at Arizona State University, speaking to Heatmap about the spread of misinformation around the LA fires
With the ongoing disaster approaching its second week, here’s where things stand.
A week ago, forecasters in Southern California warned residents of Los Angeles that conditions would be dry, windy, and conducive to wildfires. How bad things have gotten, though, has taken everyone by surprise. As of Monday morning, almost 40,000 acres of Los Angeles County have burned in six separate fires, the biggest of which, Palisades and Eaton, have yet to be fully contained. The latest red flag warning, indicating fire weather, won’t expire until Wednesday.
Many have questions about how the second-biggest city in the country is facing such unbelievable devastation (some of these questions, perhaps, being more politically motivated than others). Below, we’ve tried to collect as many answers as possible — including a bit of good news about what lies ahead.
A second Santa Ana wind event is due to set in Monday afternoon. “We’re expecting moderate Santa Ana winds over the next few days, generally in the 20 to 30 [mile per hour] range, gusting to 50, across the mountains and through the canyons,” Eric Drewitz, a meteorologist with the Forest Service, told me on Sunday. Drewitz noted that the winds will be less severe than last week’s, when the fires flared up, but he also anticipates they’ll be “more easterly,” which could blow the fires into new areas. A new red flag warning has been issued through Wednesday, signaling increased fire potential due to low humidity and high winds for several days yet.
If firefighters can prevent new flare-ups and hold back the fires through that wind event, they might be in good shape. By Friday of this week, “it looks like we could have some moderate onshore flow,” Drewitz said, when wet ocean air blows inland, which would help “build back the marine layer” and increase the relative humidity in the region, decreasing the chances of more fires. Information about the Santa Anas at that time is still uncertain — the models have been changing, and the wind is tricky to predict the strength of so far out — but an increase in humidity will at least offer some relief for the battered Ventura and Orange Counties.
The Palisades Fire, the biggest in L.A., ripped through the hilly and affluent area between Santa Monica and Malibu, including the Pacific Palisades neighborhood, the second-most expensive zip code in Los Angeles and home to many celebrities. Structures in Big Rock, a neighborhood in Malibu, have also burned. The fire has also encroached on the I-405 and the Getty Villa, and destroyed at least two homes in Mandeville Canyon, a neighborhood of multimillion-dollar homes. Students at nearby University of California, Los Angeles, were told on Friday to prepare for a possible evacuation.
The Eaton Fire, the second biggest blaze in the area, has killed 16 people in Altadena, a neighborhood near Pasadena, according to the Los Angeles Times, making it one of the deadliest fires in the modern history of California.
The 1,000-acre Kenneth fire is 100% contained but still burning near Calabasas and the gated community of Hidden Hills. The Hurst Fire has burned nearly 800 acres and is 89% contained and is still burning near Sylmar, the northernmost neighborhood in L.A. Though there are no evacuation notices for either the Kenneth or the Hurst fires, residents in the L.A. area should monitor the current conditions as the situation continues to be fluid and develop.
The 43-acre Sunset Fire, which triggered evacuations last week in Hollywood and Hollywood Hills, burned no homes and is 100% contained.
The Lidia Fire, which ignited in a remote area south of Acton, California, on Wednesday afternoon, burned 350 acres of brush and is 100% contained.
It can take years to determine the cause of a fire, and investigations typically don’t begin until after the fire is under control and the area is safe to reenter, Edward Nordskog, a retired fire investigator from the Los Angeles Sheriff’s Department, told Heatmap’s Emily Pontecorvo. He also noted, however, that urban fires are typically easier to pinpoint the cause of than wildland fires due to the availability of witnesses and surveillance footage.
The vast majority of wildfires, 85%, are caused by humans.So far, investigators have ruled out lightning — another common fire-starter — because there were no electrical storms in the area when the fires started. In the case of the Palisades Fire, there were no power lines in the area of the ignition, though investigators are now looking into an electrical transmission tower in Eaton Canyon as the possible cause of the deadly fire in Altadena. There have been rumors that arsonists started the fires, but investigators say that scenario is also pretty unlikely due to the spread of the fires and how remote the ignition areas are.
Officially, 24 people have died, but that tally is likely to rise. California Governor Gavin Newsom said Sunday that he expects “a lot more” deaths will be added to the total in the coming days as search efforts continue.
Incoming President Donald Trump slammed the response to the L.A. fires in a Truth Social post on Sunday morning: “This is one of the worst catastrophes in the history of our Country,” he wrote. “They just can’t put out the fires. What’s wrong with them?”
Though there is much blame going around — not all of it founded in reality — the challenges facing firefighters are immense. Last week, because of strong Santa Ana winds, fire crews could not drop suppressants like water or chemical retardant on the initial blazes. (In strong winds, water and retardant will blow away before they reach the flames on the ground.)
Fighting a fire in an urban or suburban area is also different from fighting one in a remote, wild area. In a true wildfire, crews don’t use much water; firefighters typically contain the blazes by creating breaks — areas cleared of vegetation that starve a fire of fuel and keep it from spreading. In an urban or suburban event, however, firefighters can’t simply hack through a neighborhood, and typically have to use water to fight structure fires. Their priority also shifts from stopping the fire to evacuating and saving people, which means putting out the fire itself has to wait.
What’s more, the L.A. area faced dangerous fire weather going into last week — with wind gusts up to 100 miles per hour and dry air — and the persistence of the Santa Ana winds during firefighting operations through the weekend made it extremely difficult for emergency managers to gain a foothold.
Trump and others have criticized Los Angeles for being unprepared for the fires, given reports that some fire hydrants ran dry or had low pressure during operations in Pacific Palisades. According to the Los Angeles Department of Water and Power, about 20% of hydrants were affected, mostly at higher elevations.
The problem isn’t a lack of preparation, however. It’s that the L.A. wildfires are so large and widespread, the county’s preparations were quickly overwhelmed. “We’re fighting a wildfire with urban water systems, and that is really challenging,” Los Angeles Department of Water and Power CEO Janisse Quiñones said in a news conference last week. When houses burn down, water mains can break open. Civilians also put a strain on the system when they use hoses or sprinkler systems to try to protect their homes.
On Sunday, Judy Chu, the Democratic lawmaker representing Altadena, confirmed that fire officials had told her there was enough water to continue the battle in the days ahead. “I believe that we're in a good place right now,” she told reporters. Newsom, meanwhile, has responded to criticism over the water failure by ordering an investigation into the weak or dry hydrants.
So-called “super soaker” planes have had no problem with water access; they’re scooping directly from the ocean.
Yes. Although aerial support was grounded in the early stages of the wildfires due to severe Santa Ana winds, flights resumed during lulls in the storms last week.
There is a misconception, though, that water and retardant drops “put out” fires; they don’t. Instead, aerial support suppresses a fire so crews can get in close and use traditional methods, like cutting a fire break or spraying water. “All that up in the air, all that’s doing is allowing the firefighters [on the ground] a chance to get in,” Bobbie Scopa, a veteran firefighter and author of the memoir Both Sides of the Fire Line, told me last week.
With winds expected to pick up early this week, aerial firefighting operations may be grounded again. “If you have erratic, unpredictable winds to where you’ve got a gust spread of like 20 to 30 knots,” i.e. 23 to 35 miles per hour, “that becomes dangerous,” Dan Reese, a veteran firefighter and the founder and president of the International Wildfire Consulting Group, told me on Friday.
Because of the direction of the Santa Ana winds, wildfire smoke should mostly blow out to sea. But as winds shift, unhealthy air can blow into populated areas, affecting the health of residents.
Wildfire smoke is unhealthy, period, but urban and suburban smoke like that from the L.A. fires can be particularly detrimental. It’s not just trees and brush immolating in an urban fire, it’s also cars, and batteries, and gas tanks, and plastics, and insulation, and other nasty, chemical-filled things catching fire and sending fumes into the air. PM2.5, the inhalable particulates from wildfire smoke, contributes to thousands of excess deaths annually in the U.S.
You can read Heatmap’s guide to staying safe during extreme smoke events here.
“The bad news is, I’m not seeing any rain chances,” Drewitz, the Forest Service meteorologist, told me on Sunday. Though the marine layer will bring wetter air to the Los Angeles area on Friday, his models showed it’ll be unlikely to form precipitation.
Though some forecasters have signaled potential rain at the end of next week, the general consensus is that the odds for that are low, and that any rain there may be will be too light or short-lived to contribute meaningfully to extinguishing the fires.
The chaparral shrublands around Los Angeles are supposed to burn every 30 to 130 years. “There are high concentrations of terpenes — very flammable oils — in that vegetation; it’s made to burn,” Scopa, the veteran firefighter, told me.
What isn’t normal, though, is the amount of rain Los Angeles got ahead of this past spring — 52.46 inches in the preceding two years, the wettest period in the city’s history since the late 1800s — which was followed by a blisteringly hot summer and a delayed start to this year’s rainy season. Since October, parts of Southern California have received just 10% of their normal rainfall
This “weather whiplash” is caused by a warmer atmosphere, which means that plants will grow explosively due to the influx of rain and then dry out when the drought returns, leaving lots of dry fuels ready and waiting for a spark. “This is really, I would argue, a signature of climate change that is going to be experienced almost everywhere people actually live on Earth,” Daniel Swain, a climate scientist at the University of California, Los Angeles, who authored a new study on the pattern, told The Washington Post.
We know less about how climate change may affect the Santa Anas, though experts have some theories.
At least 12,000 structures have burned so far in the fires, which is already exacerbating the strain on the Los Angeles housing market — one of the country’s tightest even before the fires — as thousands of displaced people look for new places to live. “Dozens and dozens of people are going after the same properties,” one real estate agent told the Los Angeles Times. The city has reminded businesses that price gouging — including raising rental prices more than 10% — during an emergency is against the law.
Los Angeles had a shortage of about 370,000 homes before the fires, and between 2021 and 2023, the county added fewer than 30,000 new units per year. Recovery grants and federal aid can lag, and it often takes more than two years for even the first Housing and Urban Development Disaster Recovery Grants’ expenditures to go out.
My colleague Matthew Zeitlin wrote for Heatmap that the economic impact of the Los Angeles fire is already much higher than that of other fires, such as the 2018 Camp fire, partly because of the value of the Pacific Palisades real estate.
The wildfires may “deal a devastating blow to [California’s] fragile home insurance market,” Heatmap’s Matthew Zeitlin wrote last week. In recent years, home insurers have left California or declined to write new policies, at least partially due to the increased risk of wildfires in the state.
Depending on the extent of the damage from the fires, the coffers of California’s FAIR Plan — which insures homeowners who can’t get insurance otherwise, including many in Pacific Palisades and Altadena — could empty, causing it to seek money from insurers, according to the state’s regulations. As Zeitlin writes, “This would mean that Californians who were able to buy private insurance — because they don’t live in a region of the state that insurers have abandoned — could be on the hook for massive wildfire losses.”
First and foremost, sign up for all relevant emergency alerts. Make sure to turn on the sound on your phone and keep it near you in case of a change in conditions. Pack a “go bag” with essentials and consider filling your gas tank now so that you can evacuate at a moment’s notice if needed. Read our guide on what to do if you get a pre-evacuation or an evacuation notice ahead of time so that you’re not scrambling for information if you get an alert.
The free Watch Duty app has become a go-to resource for people affected by the fires, including friends and family of Angelenos who may themselves be thousands of miles away. The app provides information on fire perimeters, evacuation notices, and power outages. Its employees pull information directly from emergency responders’ radio broadcasts and sometimes beat official sources to disseminating it. If you need an endorsement: Emergency responders rely on the app, too.
There are many scams in the wake of disasters as crooks look to take advantage of desperate people — and those who want to help them. To play it safe, you can use a hub like the one established by GoFundMe, which is actively vetting campaigns related to the L.A. fires. If you’re looking to volunteer your time, make a donation of clothing or food, or if you’re able to foster animals the fire has displaced, you can use this handy database from the Mutual Aid Network L.A. There are also many national organizations, such as the Red Cross, that you can connect with if you want to help.
The City of Los Angeles and the Los Angeles Fire Department have asked that do-gooders not bring donations directly to fire stations or shelters; such actions can interfere with emergency operations. Their website provides more information about how you can help — productively — on their website.