The Brief

We all know it’s hot — and getting hotter.

According to NOAA and NASA, the 10 warmest years globally since 1850 have all occurred in the past decade. In less than 200 years, when the Industrial Revolution began, the global average temperature has increased by more than two degrees Fahrenheit.

While the planet’s climate has changed dramatically over millions of years, atmospheric carbon dioxide levels are now at their highest in millenia due to pollution from human society. Scientific consensus proves the modern, rapid weather shifts we're now experiencing are a result of how we humans, largely through fossil fuel pollution, are changing the climate.

The science is clear that we’re entering a new era of extreme heat. We’re unlikely to keep global temperatures below the threshold scientists have raised the alarm about for years, and weather extremes will only become more frequent and intense if we don’t dramatically cut emissions in the next seven years or soon after.

So, as the earth heats up, what is “normal” vs “extreme” heat? How is the climate crisis affecting heat here in Southern California?

Normal heat in the Southland

Of course, July through September and even much of October in southern California, it's normal for the weather to heat up. Southern California has deserts, mountains and the ocean, so our temperatures vary widely. From geography to tree cover to local weather patterns, there are a lot of factors that naturally make some parts of Southern California hotter than others. My colleague, science reporter Jacob Margolis, explains in more detail in this story.

'Extreme' vs 'normal' heat

What’s normal versus extreme depends on where you live — after all, what’s considered a hot day in Santa Monica is a far cry from a hot day in Palm Springs.

The climate crisis is shifting average temperatures hotter — not every day, or every season, but it’s driving an average increase in both day and nighttime temperatures.

How the climate crisis is expected to affect heat in California.

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That also means longer and more frequent “heat waves,” during which temperatures reach higher extremes and stay there for longer periods of time. A week-long heat wave in early September 2022 was the hottest and longest in the state’s record for that month, which is already one of the hottest months in California.

“Whether you're on the coast, whether you're in the mountains, whether you're in the deserts, whether you're in between, all those averages are going up,” said Alex Tardy, a meteorologist with the National Weather Service (NWS) San Diego office.

In Southern California, the most rapid and dramatic increases are happening in the deserts and the mountains, already extreme environments, Tardy said.

Doing the math

Since 1901, the National Oceanic and Atmospheric Administration (NOAA) has collected temperature records from weather stations across the country. They use that information, combined with other data and computer models to calculate specific “climate normals” for different regions.

The “normals” add up to a 30-year average temperature, or what’s considered a long-term average temperature. NOAA’s National Weather Service uses those average temperatures to decide whether a heat event is extreme or not.

“Abnormal heat is typically daytime temperatures 10 to as much as 20 degrees Fahrenheit warmer than the long-term average,” said Tardy. “When we talk about a heat wave, what we're talking about is really two or more days when temperatures are much above average.”

NOAA's latest climate normals map showing the normals from 1991-2020 minus 1981-2010 normals. Most of the U.S. shows significant warming, especially in the West, Southwest and East, where soem normals jumped by a whole degree already.

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Since our bodies take time to acclimate to changes in temperature, those averages depend on the time of year. For example, Tardy said that an abnormal threshold in mid-July in L.A would be 90 degrees, whereas it would be 110 degrees in Palm Springs.

“We look at the heat risk, we look at the departure from normal, we look at the ability for someone to be able to acclimate to the heat,” Tardy said. “We don't just look at the fact that it's a hundred degrees and that requires a heat warning.”

Every 10 years, NOAA recalculates the climate normals — most recently in 2020 — and overall, averages are going up.

“Normals and averages — it's always been a moving target, but the target is moving up and up and up and warmer and warmer and that's what we've seen the past 10 years,” said Tardy.

Six of the last 10 years have been the hottest on record in Southern California, Tardy said.

Ranking heat waves like hurricanes 

When the NWS sees abnormal temperatures in the forecast, that can spark a heat watch or excessive heat warning or advisory. These warnings are meant to help individuals stay safe, inform governments and businesses, and can trigger some legal protections for outdoor workers.

NWS is currently prototyping an extreme heat risk scale that will more directly communicate how different heat extremes translate to health risk. They've already used it in tweets about the current heat wave:

Tardy said improving early communication about the dangers of heat is especially important as the climate crisis makes heat more extreme and frequent — already, heat kills more people than any other weather event in the U.S.

“Heat is a very silent killer,” Tardy said. “It's not something that we see like a hurricane or a flood or a winter storm. It's something that just kind of catches up to you over time. It's one of those things that a lot of people don't take seriously until it happens to them.”

The idea is to rank heat waves similar to how we rank hurricanes. California lawmakers also passed a bill in 2022 requiring a statewide heat wave ranking system by 2025.

The prototype scale for ranking heat waves amid a changing climate.

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“People can really relate to the magnitude or the potential impact on a five versus a one [for a hurricane],” Tardy said. “So we're trying to do that also with heat.”

NOAA’s current prototype, which you can peruse here, uses a color scale to indicate how dangerous forecasted temperatures may be to health. NWS is currently using it to inform its official heat alerts, but it will likely be a few years before it’s used in widespread public communication.

“The overall magnitude of the event — not just, 'It's 110 degrees' — that's something we're really trying to focus on more,” Tardy said.

The scale forecasts seven days in advance and allows a more nuanced view of heat as it relates to health by incorporating data about:

• How significantly above normal the temperatures are at your location.
• The time of the year. 
• How long the unusual heat will last (will overnight temperatures get low enough to lower heat stress? How much warmer than average will those temperatures be?)

Weather forecasting has gotten a lot better, and it is another tool to save lives amid the climate crisis, Tardy said. He hopes the heat risk scale will better communicate the health dangers of heat and help people better protect themselves and their loved ones amid our hotter normal.

“We have to do a better job ingraining it into the culture — that it's not just hot all the time, it's not just hot because it's summer,” Tardy said. “When we start talking about heat alerts or heat warnings, it's something that should be treated as, ‘Hey, this is very unusual.’ And we can't just treat the day or the activity as normal.”

Staying safe in the heat

To many locals, the Los Angeles River — hugged by concrete embankments and heavy vehicle traffic — hardly seems like a river at all.

The waterway bisecting the city was converted to a giant storm drain nearly a century ago to contain flood waters. Today, it's an extension of the urban network of concrete, running beneath freeways and bridges as it collects all kinds of refuse: spent tires, scrap metal, trash thrown from car windows.

But when Doug Rosenberg came upon a shopping cart tipped over in the river's shallow waters back in 2020, he saw the potential to meet nature halfway.

"It had begun to bloom some greenery around it, and there was a great blue heron perched on the cart, hunting in this little spot," Rosenberg recalled. "That was when it clicked for me — that any 3D geometry at all in that river channel will trap sediment, will begin a micro-bloom of ecosystem."

Doug Rosenberg is trying to push the grassroots guerrilla gardening movement forward in Los Angeles.

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The 36-year-old artist saw an amusing paradox — life sprouting from the metal cart — that planted the seed for his next project: a pop-up wetland in the middle of the LA River.

In a desolate part of downtown, he pushed large rocks from the riverbanks into the water and arranged them in loose, concentric circles. The structure would trap sediment, allowing life to take root.

In other words, Rosenberg produced a patch of watery land — like a marsh or swamp — to support plants and animals.

Over the course of 10 weeks, the simple assemblage of rocks spawned a totally new 10-by-20-foot green island in the middle of the 100-foot-wide channel.

Rosenberg calls it performance art: a visual statement that carries a call to action. The wetland installation isn't quite what he'd call "impactful ecology," but rather a work of art to show environmental good can be low-tech and small-scale.

"The impetus behind this project is to show that the barrier to entry doesn't exist. To basically provide a simple format for action," he said.

Guerrilla gardeners

It's not so much that the barriers don't exist — they do — he's just flouting them, city officials say. Despite his good intentions, none of this is legal. He's a guerrilla gardener: someone who plants where they're not supposed to. The federal government deems this flood control channel "navigable water," providing protections under the Clean Water Act and making any unauthorized changes to its course illegal. That includes obstructions and modifications in the channel, such as dredging or disposal of materials like rocks.

Across the country, as urban development replaces tree cover and natural landscapes with buildings and parking lots, guerrilla gardeners flout local ordinances to disperse seeds or otherwise alter their environment, usually with an overriding mission to reclaim underused public spaces. They seek to grow healthy produce in urban food deserts, capture greenhouse gases and beautify their neighborhoods.

The movement has taken many forms, from creating a verdant oasis for the nation's largest housing project in New York City, to planting a front-yard vegetable garden in defiance of state law in Florida, to grooming a busy bike path in Seattle.

Here in LA, Rosenberg's guerrilla tactics include trespassing and planting without permits in the publicly managed waterway. Getting to his wetland requires jumping railroad tracks and scaling down the steep side of the channel to the riverbed. But as far as he's concerned, it's open to the public.

Rosenberg (right) and a few volunteers walk past railroad tracks to get to the river.

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"I feel like it's possible to relate to a city the way we're used to relating to nature — or as we imagine we could relate to unspoiled wilderness," he said.

But officials and longtime river advocates say people can't plant wherever they want, and that guerrilla actors have the potential to do more harm than good.

"Even small changes can affect water quality, habitat, and safety downstream," said Ben Orbison, a spokesman for Friends of the LA River, an advocacy group focused on revitalization efforts, including cleanups along the waterway. "Restoration is incredibly important, but works best when guided by ecology and collaboration," with local and federal agencies to prioritize safety, he added.

Chief among the concerns is flooding.

"If you have rocks, if you have vegetation, if you have other things that slow the water down then it builds up faster. That's where you get the overtopping of the channel," said Ben Harris, an attorney with Los Angeles Waterkeeper, an environmental watchdog group.

Crews place rock on the LA River's banks during channelization in 1938.

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The whole reason the Los Angeles River became a concrete straightjacket was to prevent a repeat of the city's devastating floods in the 1930s. The Army Corps of Engineers channelized and paved the once-meandering river. The roughly 51-mile channel continues to serve as a hydro-highway shuttling stormwater runoff from the mountains to the sea.

Generally, local officials and river advocates are far ahead of Rosenberg in revitalizing the channel. In recent years, the city has built several projects under a master plan designed to resurrect some of the river's natural habitat and expand public access. But progress is slow. Legal roadblocks and budget constraints have delayed the implementation of many proposals.

Beyond the bike paths and trails lining the waterway, the efforts are most visible in parts of the river where the soil was left unpaved. Willows, egrets and frogs populate soft-bottom sections where springs and a high water table would reject a concrete casing. And, upstream from Rosenberg's wetland, there's a plan in the works to build what's essentially a larger, permanent version of the artist's project. Long before Rosenberg plunked his first rock into its waters, the city adopted a plan to turn an 11-mile section of the river into a wetland to allow the safe passage of salmon.

Still, some city staff give guerrilla artists a lot of credit for laying the groundwork.

"The biggest shift points in the river's history were made, in my opinion, not necessarily the legal way," said Kat Superfisky, an urban ecologist with the city, but from "the community advocate, artist, guerrilla kind of efforts."

'He's onto something'

On social media, Rosenberg shares his art with a wider audience than was made available to his artist-activist predecessors. People curious about his project have reached out to him, asking how they can help support it. He's invited them to join him on his visits to the wetland, where he's put them to work. Others have taken issue with Rosenberg's accommodation of an invasive plant species in his wetland. It's mostly populated by Goodding's willow, a native species, and creeping water primrose, a non-native invasive. Those non-native plants tend to crowd out native habitat, drink more water and lead to increased use of toxic pesticides.

Some people accustomed to reading the river's currents say the wetland will be gone before it can cause any lasting harm to the river. In the likely event of a heavy rain, the rising tide in the river channel could wipe out the wetland, washing it into the ocean.

Canadian geese come in for a landing near the mini-wetland, in a downtown section of the LA River.

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From an ecological standpoint, Superfisky says "he's onto something," in terms of thinking about how to recreate conditions found in a natural, sprawling river using the impractical medium he's given.

The channel functions like a straight, unobstructed tube, she said. But the placement of rocks allow sediment buildup and produce varied flow patterns — much like grooves in braiding streams — to set up stiller pockets where wildlife can thrive.

But it all falls apart if he's not accounting for flood risk, the ecologist said.

Harris, of the watchdog LA Waterkeeper, thinks flood management and ecological values can coexist in a concrete channel.

Removing the concrete would open up more possibilities, he said, adding that there are "a variety of nature-based solutions" for the channel that support flood management.

Volunteer Isaac Cohen places more rocks around the guerrilla wetland.

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But an overhaul of the existing concrete flood management system would also require big shifts in mindset.

"It's kind of a scary thought," he said. "If you imagine being a policymaker in government and you're trying to do that, you have to turn things on its head."

The Army Corps of Engineers has not responded to requests for comment. According to its website, the agency works to clear vegetation it warns can clog the channel and hamper flood control. But the agency has recently prioritized the removal of non-native species due to lack of funding, the site notes.

"They probably would just talk to him and explain rather than prosecute anything, or they might just go in and take it away," said Felicia Marcus, a fellow at Stanford University's Water in the West program and a former head of the city of Los Angeles' public works department.

Rosenberg says he understands the consequences.

"If they throw a book at me, it'll be quite a big book, but I'm at the point where that's less urgent to me than making art that obviously deserves to get made," he said.

Guerrillas lay the groundwork to rewrite the rules

Passersby who look down from nearby bridges can spot the pop-up wetland.

Artists have long exploited that legal gray area around what's considered public land.

Historically, it was the late Lewis MacAdams, a poet and activist, whose guerrilla tactics expanded public access to the LA River. In 1985, MacAdams and friends cut open a fence blocking its entry and declared the river open to the people.

Through Friends of the LA River, the advocacy group he founded, MacAdams made sure the city wouldn't forget the river that birthed it. He promoted it as a resource that people should protect, restore and enjoy.

During a meeting with the county, as MacAdams told it, whenever the head of the public works department referred to the waterway as a "flood control channel," he would shoot back with "river." In 2008, kayakers carried the baton, when writer George Wolfe led a scofflaw fleet of paddlers down the entire waterway to prove that it was "navigable waters" so it could keep its Clean Water Act protections. Two years later, the Environmental Protection Agency agreed with what MacAdams had started and designated the river as navigable.

"He didn't know jack doodle scratch about the river or river ecosystems at that time. He led with his artistic passion," Superfisky said. "But then, my golly, he is the one guy that really got us to start calling it a river again."

Superfisky says Rosenberg is having his "Lewis MacAdams moment."

Knowing his wetland experiment could wash away in an instant, Rosenberg said he feels there's some wiggle room to experiment and make mistakes.

Rosenberg acknowledges the dangers that can spring from an uneducated approach. "I wouldn't push back on someone calling it reckless, to be honest," he said.

But he's more focused on the good he says can come from "vigorous action." He says that, among his millennial peers and younger generations, "a sense of attainability and agency" is lacking when it comes to helping chip away at big-picture issues like climate change.

Rosenberg acknowledges the dangers that can spring from a freewheeling approach to ecological art. But he says there's also value in "vigorous action," adding: "There's a long history in ecological actions of perfect being an argument against the good happening at all."

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He's aware that there are legal avenues available to produce ecological art. He appreciates that artist Lauren Bon, for example, has secured more than 70 permits as part of an ongoing project to divert water from the river that could irrigate a state park nearby. But Rosenberg thinks there's room for some freewheeling.

"Maybe it's not about waiting for permits or even about waiting to feel like you've mastered the material," he said. "There's a long history in ecological actions of perfect being an argument against the good happening at all."

Nature bats last

On a recent Saturday evening, during one of his public tours, Rosenberg handed out scythes and an agenda to whack away the invasive plants.

Allie Baron, a lifelong LA resident, brought her two sons with her after reaching out to Rosenberg on Instagram.

Allie Baron brought her two sons with her to help Rosenberg tend to the guerrilla wetland.

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As she gleefully tore out a creeping primrose, the 36-year-old said, "All I can do is try to make my community better and make the river pretty. You do what you can to try to restore life to things that need help."

Caught in the wetland brush was a blue rubber bullet — just like the ones LAPD officers had deployed during the anti-ICE protests held in downtown LA this summer, over immigration raids.

"One of the cool things about a structure like this is that it's trapping that stuff," Rosenberg said. "The rubber bullet was here and not in the ocean yet."

That and some oily sheen on the watery patch of willows were another reminder of the intensely urban environment.

Later, the guerrilla group witnessed a hawk snatch its dinner from the water.

A few days after that, the forecast from river pundits proved accurate. It rained, filling the channel with a fast-moving current.

"The garden is gone," Rosenberg said.

He says he'll start gardening again in the spring.
Copyright 2025 NPR

Allie Baron's son Robert carries a bunch of invasive water primrose pruned from the guerrilla wetland.

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Recent operations under the Trump administration have raised eyebrows and drawn criticism, not only because of their missions but also because of their names and the intent behind them.

Defense Secretary Pete Hegseth on Thursday announced Operation Southern Spear, aimed at what he calls "narco-terrorists" who are allegedly bringing illegal drugs into the country. The Department of Homeland Security (DHS) on Saturday also announced it was launching Operation Charlotte's Web — matching the name of the classic children's book — in Charlotte, N.C., to target undocumented immigrants.

"There is no parent who has read Charlotte's Web to a child who cannot be outraged by this," Dan Shapiro, who served as U.S. Ambassador to Israel from 2011 to 2017, wrote on X.

Asked about the inspiration for the operation name and the message the agency wants to send by using it, DHS responded to NPR with a press release about the operation that included a statement from Assistant Secretary Tricia McLaughlin.

"We are surging DHS law enforcement to Charlotte to ensure Americans are safe and public safety threats are removed," McLaughlin said in the statement. "There have been too many victims of criminal illegal aliens. President Trump and Secretary Noem will step up to protect Americans when sanctuary politicians won't."

NPR also reached out to the Defense Department for comment but has not received a response.

Here is what to know about military operation names.

Naming military operations is not new. Neither is criticism of names

Code names for U.S. military operations date back to the World War II era and began for security reasons, according to Lt. Col. Gregory C. Sieminski in the article "The Art of Naming Operations," in The US Army War College Quarterly: Parameters. The names were based on colors at first, such as Operation Indigo, but as World War II spread, military officials switched to a name-based system that included projects and locations.

After the Vietnam War, military officials started using a computer system to reconcile nicknames and code words, called the Code Word, Nickname, and Exercise Term System, or NICKA.

Routine military exercises use the NICKA system for naming operations, according to Mark Cancian, a retired Marine colonel and a senior adviser at the Center for Strategic and International Studies. Highly visible operations generally get two-word names chosen outside the system, such as operations Just Cause in Panama, Iraqi Freedom, and Enduring Freedom in Afghanistan, Cancian told NPR.

"The ones that are chosen are chosen for a reason to project a message," Cancian told NPR. "So, going back to Iraqi Freedom and Enduring Freedom, the message is freedom. With the recent ones, Midnight Hammer and Southern Spear, the message is lethality."

Although DHS is not considered part of the U.S. military, using the name "Charlotte's Web" could also have been chosen because "you've got the spider's web that catches people," but it could also be the administration trying to be "tongue in cheek," he continued.

And other military operations have received backlash and criticism in the past, including what is now known as Operation Enduring Freedom. It was first called Operation Infinite Justice, but was changed after backlash that it was offensive to Muslims.

"The fact that these names get scrutiny is not unusual," Cancian said. "Now, I think in this case, given the administration's aggressive rhetoric, I think that inspires maybe pushback, but it's not unusual that names get a lot of scrutiny."
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