Science
The Next Threat to L.A.? Rainfall That Could Cause Landslides
While winds and flames continued to ravage Los Angeles, small teams began creeping onto the charred soils left in their wake.
Roughly a dozen members of the California Watershed Emergency Response Teams and the United States Forest Service are studying the edges of the Eaton and Palisades fires to determine what patches of land burned most severely. Soon, they’ll issue hazard maps to help people prepare for what comes next: the near-certain threat of floods and landslides that will loom for days, months and even years while the city recovers.
“After a wildfire, the hazard to the public is not over,” said Jeremy Lancaster, California’s state geologist. He and his team spent Wednesday hiking in the steep canyons that flank the San Gabriel and Santa Monica Mountains. When it rains hard enough, the sediment on slopes like these can swiftly tumble downhill onto houses that increasingly push up against the fire-prone foothills.
The two major hazards after a wildfire are flash flooding and post-fire debris flows. While spongy soils typically absorb water, burned soils can become hard packed like concrete, repelling water as a raincoat would. Water then funnels downslope without much, or any, vegetation left after a fire to keep it in check.
Hazard maps use a combination of satellite images and field testing of soils to show where patches of moderately to severely burned soils could make these post-fire risks more likely. Recommendations for emergency services to engineer barricades against the danger accompany the maps.
The Palisades burn map was released on Thursday, and the Eaton map is still under review. Experts said the Palisades fire had mostly low to moderate burn severity, while the Eaton fire was likely to have more moderate to high burn severity.
Debris flows require three ingredients — steep slopes, burned soils and rain — and they’re often more dangerous than floods because the sediment they draw in claws at the landscape, creating a snowball effect that pulls a tumult of trees, vegetation, soil, rocks and anything else in its way.
“A debris flow is like a flood on steroids,” said Jason Kean, a research hydrologist with the United States Geological Survey. “It’s all bulked up with rocks and mud and trees.” While floods often have a longer reach, water churns faster in debris flows, which are less common but more destructive.
After the Thomas fire in 2017, a debris flow in Montecito, Calif., killed 23 people and damaged or destroyed more than 400 homes.
Neither homeowners’ insurance nor federal flood insurance covers the impact to properties of debris flows, which are defined by the Geologic Survey as landslides.
The fire-flood cycle is a long-studied relationship, but scientists say a warming planet has made the post-fire threat more likely. Fires burn bigger and more severely. Rains hit harder and more often. Those changes expand the target area for post-fire hazards, which could increase the size and the frequency of floods and flows.
“The fire scientists are telling us that wildfires are increasing in size and severity,” Dr. Kean said. “From that fact alone, you’re exposing more terrain and making more terrain vulnerable to post-fire problems.”
With a dangerous combination of very steep terrain, lots of sediment, high-fire activity and a lot of people pushed up against the mountains, Los Angeles faces an extreme risk.
“The Los Angeles area and Southern California are the world capital for post-fire debris flows,” Dr. Kean said.
Debris flows are so common in Los Angeles that at the edge of the San Gabriel Mountains, where the Eaton fire burned, the state has carved debris basins to collect waste from major flow events. In Southern California, more than two million people live on alluvial fans, landforms that are conducive to flash floods and debris flows, according to Dr. Lancaster.
The National Weather Service in Los Angeles collaborated with the Geological Survey to start the nation’s first early warning systems for these post-fire hazards in 2005. The geological survey sets a rainfall threshold that could set off landslides, and the Weather Service issues a warning if the rainfall they expect nears or surpasses it.
Jayme Laber, a senior hydrologist with the Los Angeles forecast office, has spent the last two decades issuing such warnings. While there’s still no sign of rain in the seven to 10 day forecast he issued on Wednesday, a garden-variety rainstorm that Angelenos see at least once or twice a year could be enough to kick off the next wave of hazards, which can develop within minutes.
“In a burned area, the kind of rain that would not cause problems would be a really light drizzly rain that just goes on and on,” Mr. Laber said. But at some point this winter, he added, “we’re going to get rainfall that has the potential to cause flash flooding and debris flows in these newly burned areas.”
This video of a small debris flow from 2016, which is close to the site of the current Eaton fire, shows how quickly large objects, like a six-foot boulder, can be sent rushing downhill.
Mr. Laber advised residents to prepare in case of a future evacuation, monitor the forecast and pay attention to local emergency officials if a warning is issued.
Science
Why California’s milk cartons may lose their coveted recycling symbol
California milk cartons may lose their coveted recycling symbol, the one with the chasing arrows, potentially threatening the existence of the ubiquitous beverage containers.
In a letter Dec. 15, Waste Management, one of the nation’s largest waste companies, told the state the company would no longer sort cartons out of the waste stream for recycling at its Sacramento facility. Instead, it will send the milk- and food-encrusted packaging to the landfill.
Marcus Nettz, Waste Management’s director of recycling for Northern California and Nevada, cited concerns from buyers and overseas regulators that cartons — even in small amounts — could contaminate valuable material, such as paper, leading them to reject the imports.
The company decision means the number of Californians with access to beverage carton recycling falls below the threshold in the state’s “Truth in Recycling” law, or Senate Bill 343.
And according to the law, that means the label has to come off.
The recycling label is critical for product and packaging companies to keep selling cartons in California as the state’s single-use packaging law goes fully into effect. That law, Senate Bill 54, calls for all single-use packaging to be recyclable or compostable by 2032. If it isn’t, it can’t be sold or distributed in the state.
The labels also provide a feel-good marketing symbol suggesting to consumers the cartons won’t end up in a landfill when they’re discarded, or find their way into the ocean where plastic debris is a large and growing problem.
On Tuesday, the state agency in charge of waste, CalRecycle, acknowledged Waste Management’s change.
In updated guidelines for the Truth in Recycling law, recycling rates for carton material have fallen below the state threshold.
It’s a setback for carton manufacturers and their customers, including soup- and juice-makers. Their trade group, the National Carton Council, has been lobbying the state, providing evidence that Waste Management’s Sacramento Recycling and Transfer Station successfully combines cartons with mixed paper and ships it to Malaysia and other Asian countries including Vietnam, proving that there is a market. The Carton Council persuaded CalRecycle to reverse a decision it made earlier this year that beverage cartons did not meet the recycling requirements of the Truth in Recycling law.
Brendon Holland, a spokesman for the trade group, said in an email that his organization is aware of Waste Management’s decision, but its understanding is that the company will now sort the cartons into their own dedicated waste stream “once a local end market is available.”
He added that even with “this temporary local adjustment,” food and beverage cartons are collected and sorted in most of California, and said this is just a “temporary end market adjustment — not a long-term shift away from historical momentum.”
In 2022, Malaysia and Vietnam banned imports of mixed paper bales — which include colored paper, newspapers, magazines and other paper products — from the U.S. because they were so often contaminated with non-paper products and plastic, such as beverage cartons. Waste Management told The Times on Dec. 5 that it has a “Certificate of Approval” by Malaysia’s customs agency to export “sorted paper material.” CalRecycle said it has no regulatory authority on “what materials may or may not be exported.”
Adding the Sacramento facility to the list of waste companies that were recycling cartons meant that the threshold required by the state had been met: More than 60% of the state’s counties had access to carton recycling.
At the time, CalRecycle’s decision to give the recycling stamp to beverage cartons was controversial. Many in the environmental, anti-plastic and no-waste sectors saw it as a sign that CalRecycle was doing the bidding of the plastic and packaging industry, as opposed to trying to rid the state of non-recyclable, polluting waste — which is not only required by law, but is something state Atty. Gen. Rob Bonta is investigating.
Others said it was a sign that the Truth in Recycling law was working: Markets were being discovered and in some cases, created, to provide recycling.
“Recyclability isn’t static, it depends on a complicated system of sorting, transportation, processing, and, ultimately, manufacturers buying the recycled material to make a new product,” said Nick Lapis, director of advocacy for Californians Against Waste.
He said this new information, which will likely remove the recycling label from the cartons, also underscores the effectiveness of the law.
“By prohibiting recyclability claims on products that don’t get recycled, SB 343 doesn’t just protect consumers. It forces manufacturers to either use recyclable materials or come to the table to work with recyclers, local governments and policymakers to develop widespread sustainable and resilient markets,” he said.
Beverage and food cartons — despite their papery appearance — are composed of layers of paper, plastic and sometimes aluminum. The sandwiched blend extends product shelf life, making it attractive to food and beverage companies.
But the companies and municipalities that receive cartons as waste say the packaging is problematic. They say recycling markets for the material are few and far between.
California, with its roughly 40 million residents, has some of the strictest waste laws in the nation. In 1989, the state passed legislation requiring cities, towns and municipalities to divert at least 50% of their residential waste away from landfills. The idea was to incentivize recycling and reuse. However an increasing number of products have since entered the commercial market and waste stream — such as single use plastics, polystyrene and beverage cartons — that have limited (if any) recycling potential, can’t be reused, and are growing in number every year.
Fines for municipalities that fail to achieve the required diversion rates can run $10,000 a day.
As a result, garbage haulers often look for creative ways to deal with the waste, including shipping trash products overseas or across the border. For years, China was the primary destination for California’s plastic, contaminated paper and other waste. But in 2018, China closed its doors to foreign garbage, so U.S. exporters began dumping their waste in smaller southeast Asian countries, including Malaysia and Vietnam.
They too have now tried to close the doors to foreign trash as reports of polluted waterways, chokingly toxic air, and illness grows — and as they struggle with inadequate infrastructure to deal with their own domestic waste.
Jan Dell, the founder and CEO of Last Beach Cleanup, released a report with the Basel Action Network, an anti-plastic organization, earlier this month showing that the Sacramento facility and other California waste companies were sending bales of carton-contaminated paper to Malaysia, Vietnam and other Asian nations.
According to export data, public records searches and photographic evidence collected by Dell and her co-authors at the Basel Action Network, more than 117,000 tons or 4,126 shipping containers worth of mixed paper bales were sent by California waste companies to Malaysia between January and July of this year.
Dell said these exports violate international law. A spokesman for Waste Management said the material they were sending was not illegal — and that they had received approval from Malaysia.
However, the Dec. 15 letter suggests they were receiving more pushback from their export markets than they’d previously disclosed.
“While certain end users maintain … that paper mills are able to process and recycle cartons,” some of them “have also shared concerns … that the inclusion of cartons … may result in rejection,” wrote Nettz.
Dell said she was “pleased” that Waste Management “stopped the illegal sortation of cartons into mixed paper bales. Now we ask them and other waste companies to stop illegally exporting mixed paper waste to countries that have banned it.”
Science
Video: Why Scientists Are Performing Brain Surgery on Monarchs
new video loaded: Why Scientists Are Performing Brain Surgery on Monarchs
By Alexa Robles-Gil, Leila Medina, Joey Sendaydiego and Mark Felix
December 23, 2025
Science
Video: Engineer Is First Paraplegic Person in Space
new video loaded: Engineer Is First Paraplegic Person in Space
transcript
transcript
Engineer Is First Paraplegic Person in Space
A paraplegic engineer from Germany became the first wheelchair user to rocket into space. The small craft that blasted her to the edge of space was operated by Jeff Bezos’ company Blue Origin.
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Capsule touchdown. There’s CM 7 Sarah Knights and Jake Mills. They’re going to lift Michi down into the wheelchair, and she has completed her journey to space and back.
December 21, 2025
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