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
What’s in a Name? For These Snails, Legal Protection
The sun had barely risen over the Pacific Ocean when a small motorboat carrying a team of Indigenous artisans and Mexican biologists dropped anchor in a rocky cove near Bahías de Huatulco.
Mauro Habacuc Avendaño Luis, one of the craftsmen, was the first to wade to shore. With an agility belying his age, he struck out over the boulders exposed by low tide. Crouching on a slippery ledge pounded by surf, he reached inside a crevice between two rocks. There, lodged among the urchins, was a snail with a knobby gray shell the size of a walnut. The sight might not dazzle tourists who travel here to see humpback whales, but for Mr. Avendaño, 85, these drab little mollusks represent a way of life.
Marine snails in the genus Plicopurpura are sacred to the Mixtec people of Pinotepa de Don Luis, a small town in southwestern Oaxaca. Men like Mr. Avendaño have been sustainably “milking” them for radiant purple dye for at least 1,500 years. The color suffuses Mixtec textiles and spiritual beliefs. Called tixinda, it symbolizes fertility and death, as well as mythic ties between lunar cycles, women and the sea.
The future of these traditions — and the fate of the snails — are uncertain. The mollusks are subject to intense poaching pressure despite federal protections intended to protect them. Fishermen break them (and the other mollusks they eat) open and sell the meat to local restaurants. Tourists who comb the beaches pluck snails off the rocks and toss them aside.
A severe earthquake in 2020 thrust formerly submerged parts of their habitat above sea level, fatally tossing other mollusks in the snail’s food web to the air, and making once inaccessible places more available to poachers.
Decades ago, dense clusters of snails the size of doorknobs were easy to find, according to Mr. Avendaño. “Full of snails,” he said, sweeping a calloused, violet-stained hand across the coves. Now, most of the snails he finds are small, just over an inch, and yield only a few milliliters of dye.
Science
Video: This Parrot Has No Beak, But Is at the Top of the Pecking Order
new video loaded: This Parrot Has No Beak, But Is at the Top of the Pecking Order
By Meg Felling and Carl Zimmer
April 20, 2026
Science
Contributor: Focus on the real causes of the shortage in hormone treatments
For months now, menopausal women across the U.S. have been unable to fill prescriptions for the estradiol patch, a long-established and safe hormone treatment. The news media has whipped up a frenzy over this scarcity, warning of a long-lasting nationwide shortage. The problem is real — but the explanations in the media coverage miss the mark. Real solutions depend on an accurate understanding of the causes.
Reporters, pharmaceutical companies and even some doctors have blamed women for causing the shortage, saying they were inspired by a “menopause moment” that has driven unprecedented demand. Such framing does a dangerous disservice to essential health advocacy.
In this narrative, there has been unprecedented demand, and it is explained in part by the Food and Drug Administration’s recent removal of the “black-box warning” from estradiol patches’ packaging. That inaccurate (and, quite frankly, terrifying) label had been required since a 2002 announcement overstated the link between certain menopause hormone treatments and breast cancer. Right-sizing and rewording the warning was long overdue. But the trouble with this narrative is that even after the black-box warning was removed, there has not been unprecedented demand.
Around 40% of menopausal women were prescribed hormone treatments in some form before the 2002 announcement. Use plummeted in its aftermath, dipping to less than 5% in 2020 and just 1.8% in 2024. According to the most recent data, the number has now settled back at the 5% mark. Unprecedented? Hardly. Modest at best.
Nor is estradiol a new or complex drug; the patch formulation has existed for decades, and generic versions are widely manufactured. There is no exotic ingredient, no rare supply chain dependency, no fluke that explains why women are suddenly being told their pharmacy is out of stock month after month.
The story is far more an indictment of the broken insurance industry: market concentration, perverse incentives and the consequences of allowing insurance companies to own the pharmacy benefit managers that effectively control drug access for the majority of users. Three companies — CVS Caremark, Express Scripts and OptumRx — manage 79% of all prescription drug claims in the United States. Those companies are wholly owned subsidiaries of three insurance behemoths: CVS Health, Cigna and UnitedHealth Group, respectively. This means that the same corporation that sells you your insurance plan also decides which drugs get covered, at what price, and whether your pharmacy can stock them. This is called vertical integration. In another era, we might have called it a cartel. The resulting problems are not unique to hormone treatments; they have affected widely used medications including blood thinners, inhalers and antibiotics. When a low-cost generic such as estradiol — a medication with no blockbuster profit margins and no patent protection — runs into friction in this system, the friction is not random. It is structural. Every decision in that chain is filtered through the same corporate profit motive. And when the drug in question is an off-patent estradiol patch that has negligible profit margins because of generic competition but requires logistical investment to keep consistently in stock? The math on “how much does this company care about ensuring access” is not complicated.
Unfortunately, there is little financial incentive to ensure smooth, consistent access. There is, however, significant financial incentive to steer patients toward branded alternatives, or simply to let supply tighten — because the companies aren’t losing much profit if sales of that product dwindle. This is not a conspiracy theory: The Federal Trade Commission noted this dynamic in a report that documented how pharmacy benefit managers’ practices inflate costs, reduce competition and harm patient access, particularly for independent pharmacies and for generic drugs.
Any claim that the estradiol patch shortage is meaningfully caused by more women now demanding hormone treatments is a distraction. It is also misogyny, pure and simple, to imply that the solution to the shortage is for women’s health advocates to dial it down and for women to temper their expectations. The scarcity of estradiol patches is the outcome of a broken system refusing to provide adequate supply.
Meanwhile, there are a few strategies to cope.
- Ask your prescriber about alternatives. Estradiol is available in multiple formulations, including gel, spray, cream, oral tablet, vaginal ring and weekly transdermal patch, which is a different product from the twice-weekly patch and may be more consistently available depending on manufacturer and region.
- Consider an online pharmacy. Many are doing a good job locating and filling these prescriptions from outside the pharmacy benefit manager system.
- Call ahead. Patch shortages are inconsistent across regions and distributors. A call to pharmacies in your area, or a broader geographic radius if you’re able, can locate stock that your regular pharmacy doesn’t have.
- Consider a compounding pharmacy. These sources can sometimes meet needs when commercially manufactured products are inaccessible. The hormones used are the same FDA-regulated bulk ingredients.
Beyond those Band-Aid solutions, more Americans need to fight for systemic change. The FTC report exists because Congress asked for it and committed to legislation that will address at least some of the problems. The FDA took action to change the labeling on estrogen in the face of citizen and medical experts’ pressure; it should do more now to demand transparency from patch manufacturers.
Most importantly, it is on all of us to call out the cracks in the current system. Instead of repeating “there’s a patch shortage” or a “surge in demand,” say that a shockingly small minority of menopausal women still even get hormonal treatments prescribed at all, and three drug companies control the vast majority of claims in this country. Those are the real problems that need real solutions.
Jennifer Weiss-Wolf, the executive director of the Birnbaum Women’s Leadership Center at New York University School of Law, is the author of the forthcoming book “When in Menopause: A User’s Manual & Citizen’s Guide.” Suzanne Gilberg, an obstetrician and gynecologist in Los Angeles, is the author of “Menopause Bootcamp.”
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