Science
Most of California’s public K-12 students go to school on campuses with virtually no shade
The vast majority of urban, public grade schools in California are paved-over “nature deserts” sorely lacking in trees or shade — leaving most of the state’s 5.8 million school-age children to bake in the sun during breaks from the classroom as rising global temperatures usher in more dangerous heat waves.
That’s the conclusion of a team of California researchers from UCLA, UC Davis and UC Berkeley who studied changes in the tree cover at 7,262 urban public schools across the Golden State between 2018 through 2022.
The ongoing joint project, which drew from urban tree canopy maps developed by study partners the California Department of Forestry and Fire Protection and the U.S. Forest Service, revealed that 85% of the schools lost about 1.8% of tree cover on average in that four-year span.
The situation appears to be just as worrisome today, the team said.
The researchers also collaborated with the nonprofit Green Schoolyards America, which found in its own 2024 study that California’s public K-12 schoolyards have a median tree cover of just 6.4%. And more than half of that canopy exists only as decoration at school entrances, in parking lots and along campus perimeters.
“Extreme heat is becoming a major public health concern in California and across the country, and trees can play a really big role in helping us cool down those schools and also build climate resilience,” said Kirsten Schwarz, the research lead at UCLA.
Results from the 2018 to 2022 study, which was funded by the U.S. Forest Service, were recently published in the journal Urban Forestry and Urban Planning.
While 15% of the schools surveyed saw gains in tree cover thanks in part to schoolyard greening projects — particularly in the Central Valley, around Sacramento and in Imperial County — many individual schools surveyed experienced big losses in net tree cover in that time. In some cases, those added up to more than 40%.
Among the state’s largest school districts, San Francisco had the greatest canopy loss, 16.3%. On the other end of the spectrum, Sacramento had the greatest gain at 7.5%, followed by Long Beach, which saw a 4% canopy increase.
Schools in Los Angeles showed a small net loss of 0.5%. The researchers cautioned not to read too much into that modest figure, because longstanding disparities in tree cover and shade across the city still expose schools in poorer neighborhoods away from the ocean to greater sun and intense outdoor heat than schools that benefit from their proximity to cooling ocean breezes and lingering marine cloud cover.
As part of the continuing data collection, the team conducted new field research in a subset of schools this summer — some in Southern California, some in the Bay Area and some in the Central Valley. Due to research agreements with the different districts, Schwarz said she could not disclose the exact locations.
Researchers from UCLA performed a complete tree inventory for 16 schools in each district, counting all of the trees they found on a campus, mapping their exact locations, identifying the many different species they came across, measuring trees at the base and crown and assessing the overall health of each tree.
Accompanying the UCLA researchers to a selection of schools in each district were researchers from UC Davis who took heat measurements.
They brought portable weather stations and sensors, as well as swatches of different paving materials such as grass, mulch, turf, rubber and concrete to each site. The researchers took thermal images, captured air temperatures and measured the humidity around the surface materials at different times of day when kids are most likely to be outside at school. This allowed the team to examine the microclimates that are specific to those campuses over an extended span.
It’s important to measure outdoor temperatures on school property because children spend so much of their time at school during the academic year and because their smaller statures place them at increased risk from heat radiating from pavement, said Alessandro Ossola, an urban plant scientist who leads the UC Davis team.
Children also haven’t fully developed the ability to regulate their body temperature they way adults can, making them more vulnerable to extreme heat and potentially hindering their ability to learn.
In addition, Ossola stressed that for children who live in places without grass or safe parks and playgrounds, school might be the one place where they can experience cooling outdoor environments and unpaved surfaces.
“With that information combined — looking at the complete tree inventory and looking at the really extensive heat measurements on an individual campus — we can better understand the cooling benefits of those trees,” Schwarz said. “We can also look at what tree species that are there and how well-adapted they are to future climate change.”
Schwarz said the team also interviewed locals at each location to find who is taking care of the trees at schools, what barriers exist that prevent good tree maintenance and what programs are in place to make tree care easier.
There are many obstacles to making campuses more hospitable. Schwarz cited a 2024 policy report by her UCLA team that examined the greening of inadequately shaded schools and policies that make it difficult to carry out improvements. In some cases, a lack of staffing, bureaucratic hurdles, state seismic safety standards that encourage building outward rather than vertically and funding models that prioritize low-maintenance campuses stood in the way of schoolyard greening, that report said.
Schwarz, an urban ecologist, said she was surprised to learn about the extent to which regulations requiring non-grass surfaces for sports and outdoor physical education dictated the design of some schoolyards.
Other schools have to choose between conflicting long-term priorities, the student report said: Plans for the future construction of additional classrooms to accommodate growing student enrollments can outweigh the desire to create shadier open spaces.
The tree canopy researchers plan to present each participating school with a tree inventory, analysis of findings, policy recommendations and suggestions for incorporating their study into classroom lessons and parent outreach.
The researchers said their main motivation in initiating the study was to help communities get the most from $150 million in Cal Fire grants approved by the state Legislature that schools can apply for to plant grass and trees on their campuses and reduce the harm of heat-radiating surfaces such as asphalt.
“That’s a really key part of this conversation about schoolyard greening, because de-paving is that critical first step,” Schwarz said. “The overarching goal is, how can we maximize these investments that we’re making in school greening?”
Ossola said that in some ways, Californians who want to improve their children’s schoolyards are playing catchup even with community will and funding sources in place. It can take decades for young trees planted today to mature enough to provide the necessary cooling effects that can make children safer on a warming planet.
“This is a critical investment that we should’ve done 20 or 50 years ago,” Ossola said. “Now we’re kind of missing the bus.”
Science
Video: NASA Announces Artemis III Crew
new video loaded: NASA Announces Artemis III Crew
transcript
transcript
NASA Announces Artemis III Crew
NASA announced the crew of Artemis III mission, which will fly to low-Earth orbit to test rendezvous and docking maneuvers with one or two lunar landers.
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“I am excited to welcome you as the next crew in the Artemis journey to successfully return to the moon — this time to stay.” “I’m honored by the role that I’ve been given. I’m also very humbled by the task in front of us. But first and foremost, I’m grateful.” “So with that, the Artemis II crew, comrade, hands you the baton. You got the controls.” “As you know, we had a significant anomaly at our Launch Complex 36A on May 28. We’ve redoubled our efforts and are moving forward.”
By Alisa Shodiyev Kaff
June 9, 2026
Science
Santa Monica Mountains’ last steelhead trout survived the Palisades fire — and even had babies
Scientists feared the Santa Monica Mountains’ last remaining steelhead trout were dead, smothered by debris flows unleashed by the Palisades fire.
But the endangered fish surprised them: A team of biologists recently spotted 30 of the rare trout — and 21 babies — in Topanga Creek.
“There was a lot of happy dancing in the creek,” said Rosi Dagit, principal conservation biologist for the Resource Conservation District of the Santa Monica Mountains, which works with public and private landowners to conserve natural resources.
That’s because the steelhead here are endangered, at both the state and federal levels. Once, they swam in most streams of the Santa Monicas, but their numbers plummeted amid overfishing and coastal development. Increasingly frequent wildfire has further stressed their habitat. Topanga Creek, a biodiversity hot spot, is home to their last known population in the mountains that stretch from the Hollywood Hills to Point Mugu in Ventura County.
The trout that were spotted, including this one, are part of a distinct Southern California population that’s listed as endangered at the state and federal levels.
(RCDSMM Stream Team)
The California Department of Fish and Wildlife spearheaded a complex mission to rescue trout threatened by the Palisades fire that sparked in January 2025.
Time was of the essence. The fire hadn’t yet been fully contained. But rain was on the way, which would sweep massive amounts of sediment from the denuded hillsides into the water. Fish are often killed this way.
Crews stunned the fish with electricity, scooped them up in buckets, trucked them to a hatchery and ultimately moved them to Arroyo Hondo Creek in Santa Barbara County.
Within days, Topanga Creek was choked with mud. Some assumed the fish left behind were goners.
But in March, the conservation district’s team found four. The following month, when water conditions were clearer, they saw more.
“These fish continue to amaze me,” said Kyle Evans, environmental program manager for the state Department of Fish and Wildlife, who had seen the damage to the creek. “I had seen populations get wiped out in similar situations. So when I heard, I was thrilled.”
Evans surmises the fish that survived were in an area of the creek where less charred material and sediment were swept in.
“These fish likely hunkered down, were hiding under some rocks or places to try to get away from the main concentration of flow,” he said. “And luckily they weren’t buried.”
The ones that were spotted were fairly small, around 6 to 14 inches. Rainbow trout and steelhead trout are the same species, but with different lifestyles. If the fish remain in freshwater, they’ll be considered rainbows. However, they can migrate to the ocean and become steelhead, where they typically grow larger before returning to their natal waters to spawn.
Topanga Creek hasn’t fully recovered from the damage it sustained, but scientists say it’s looking better. Surveys last year were “so depressing,” Dagit said, with very few animals, and stretches that were essentially transformed into flat roads from all the sediment buildup. Some of the riparian canopy burned right down to the creek.
Then came 32 inches of rain over the last nine months, scouring out and moving sediment, creating deeper pools. Dagit said they recently found newt egg masses for the first time in years, as well as a few adult newts and many frogs. Plants that provide cover are starting to recover.
She provided photos comparing certain pools last year and this year, some dramatically transformed. In September 2025, the Shrine Pool could have been an overgrown hiking trail. This April, it was filled with shallow water.
The Shrine Pool in September 2025, left, and the same location in April 2026, right, with RCDSMM’s Isaac Yelchin donning a wetsuit.
(RCDSMM Stream Team)
Topanga Creek is home to another endangered fish, the small but hardy northern tidewater goby, often described as cute. Not long before the trout operation, Dagit led a rescue of hundreds of these fish too. Many were repatriated to the lagoon at the mouth of the creek in a moving ceremony last June.
There’s still the matter of what to do with the trout that were moved to Santa Barbara County last year. Evans would like to bring them home to the Santa Monicas at some point, but isn’t sure if it will happen. On one hand, they could bolster the small, genetically isolated surviving population. On the other, they might inadvertently bring in a disease or bacteria. There is some time to decide. Evans estimates the creek still needs to recover for two to three more years.
For now, the fish are functioning fine in their adopted creek. Experts worried the trauma wrought by the move would disrupt their spawning process, but they had babies that spring. This year, they spawned again.
Science
Pacifica pier cracks, another coastal casualty as seas continue to rise
The Pacifica Municipal Pier was shut down and taped off Thursday after city workers noticed cracks running through the landmark structure and concrete chunks falling into the ocean.
It’s just one of many coastal California structures that have recently crumbled under pressure from a rising and relentless ocean.
Officials from the small, beach city south of San Francisco said the pier was closed due to “cracking, separation, and displacement of the concrete walkway and structural elements.”
It will stay closed while structural engineers asses its safety.
Photos taken by city employees show a wide crack that runs from top to bottom and across the structure as well. Other photos show a large horizontal crack under the foundation of a small restaurant on the pier, the Chit Chat Cafe.
The cafe was also shut down.
This is not the first time the 53-year-old pier has shown signs of stress. In 2021, part of it was shut down after handrails along the edge collapsed. And in 2023, after a series of storms pummeled the Central California coast, damaging parts of the pier, the structure was partially closed for more than year.
Those same storms caused extensive damage in Aptos and Capitola, 70 miles south, where piers and waterfront infrastructure were swept away or damaged.
In 2024, a 150- to 180- foot section of the Santa Cruz wharf was ripped off by powerful waves.
At least 10 of the state’s dozens of coastal public piers were closed for part or all of 2024 due to structural damage sustained in winter storms since 2022. At least five others have longer-term upgrades planned to address structural issues.
“These things are costly to maintain,” said Zach Plopper, senior environmental director at Surfrider. “They are a part of our California coastal culture in many ways, but we’re going to need to reckon with, one, the state that they’re in, and two, the continuous and worsening threats they’re going to experience,”
He said most of the piers were constructed in the early 1900s, and they weren’t built to withstand decades of rough seas, storms and rising sea level.
“With this incoming El Niño, which is forecasted to be significant, and this marine heat wave we’re in the midst of, we’re kind of in uncharted waters as far as what this winter could bring in terms of storms and swells to the California coast, and we’re likely going to see a lot more damage,” he said. “Not just piers, but roads and other coastal infrastructure up and down the state.”
There was no storm in Pacifica earlier this week, so no single event could be blamed for the destruction.
However, a 2025 report from an outside engineering firm, GHD, found that several sections of the pier were in “poor” or “serious” condition, and they recommended closure before anticipated storms or events that could “subject the piles to high winds, swells and large waves.”
The firm found several areas of the pier where concrete was missing and rebar was exposed and corroding.
“The pier has continued to experience high winds and large waves in a harsh marine environment,” the engineers wrote in the report, noting that continuous exposure to seawater or marine spray was “detrimental” to the structure.
A 2023 city report estimated it would cost $19 million to repair.
That same year, a state law was enacted to require local governments along the California coast to plan for sea level rise in the coming decades.
Sea level has risen some 8 inches, on average, along the coast in the past 150 years, Plopper said, and researchers anticipate another foot in the next 25 years.
“We’re going to see profound shifts on our coastline, none that we have ever experienced before, and building static structures on the coast just doesn’t work all that well,” he said. “We’re going to have to make some really hard decisions.”
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