Climate Change Affects Students’ Well-Being: Case Study of Extreme Heat in San Joaquin Valley and Need for Climate-Smart Schools

November 7, 2019 | 5:26 pm
PV system at Lick Wilmerding school in San Francisco, Californiamjmonty/Flickr
Jamesine Rogers Gibson
Former Contributor

Education is a fundamental right, codified in the constitutions of nearly half of the 50 states including California and in international law. Schools are expected to provide safe and healthy environments for children to learn and grow. Yet many are ill-equipped to protect them from the heatwaves, floodswildfires, and droughts that are happening in increasing number and severity across the nation. The repercussions can be huge, affecting school finances, students’ health and academic performance, and communities. With limited budgets and lengthy deferred maintenance lists, building a resilient school may not be top of mind but, with climate change amplifying these extreme events, it should be.

UCS analyzed how rising heat stress levels would affect students in the San Joaquin Valley, California as a case study of why climate-smart infrastructure is critical to protect children in a warming future. Many children in the region are at high risk of heat-related illness. Rising temperatures would reduce the window of time that it is safe for these children to be active outdoors, potentially disrupting health-promoting activities like exercise, further interrupting everyday life, and reinforcing the importance of reliable cooling and climate-safe infrastructure and school facilities. This analysis illustrates just one of many reasons that our schools must be prepared for a future of more climate extremes.

Schools built for the past climate, not a future of more extremes

Like many other types of infrastructure, schools have traditionally been designed and built using past climate and weather trends to predict the future. Previously, this assumption was reasonable, but global warming is making it increasingly invalid. Instead, the future will bring increased variability and longer, more frequent, and more intense heat waves, droughts, heavy precipitation and flooding. While the degree and type of impact may vary by location, no part of the nation will be left untouched. The crumbling state of our school facilities, which earned a “D+” from American Society of Civil Engineers, leaves them even more vulnerable to these impacts.

Recent events like 2018’s Camp Fire in California remind us what can happen if school facilities are not ready. The fire resulted in the loss of more than 80 lives destroying schools and students’ homes, and, combined with concurrent fires in other parts of the state, its smoke led to the closure of more than 180 school districts across the state (with impacts on 1.1 million students). In recent weeks, Public Safety Power Shutoffs to prevent wildfires left many schools without power and no choice but to close. The impacts of a changing climate aren’t isolated to California. Schools without air conditioning in Baltimore and Columbus, Ohio, shut their doors during the record-breaking heatwave last month. Historic flooding in the Midwest this year led to the closing of nearly 20 school districts.

Millions of students in the United States currently attend schools in “flood-risk areas.”

Everyone pays the penalty 

The penalty paid by students, schools, and communities when unprepared schools are hit by these extreme weather events is far-reaching. Schools are left scrambling to make up missed days. Parents and other caregivers may need to miss work to care for their children. Flooding restricts access to campuses and bus routes, while mold and mildew create health concerns. Rehabilitation of buildings after smoke and water damage can be expensive. Hotter days increase students’ risks of heat-related illness and reduce their performance in the classroom, particularly those living in low-income communities or communities of color. Exposure to high outdoor temperatures is intensified through commonly used heat-retaining materials that cover walls, playgrounds, parking surfaces, etc. that create “mini heat islands” and burn risks.* Hotter temperatures mean higher cooling needs to keep students comfortable indoors which can lead to increased electricity use and energy bills that consume a larger fraction of limited budgets.  These events can have a domino effect when more and more homes are destroyed and migration away from at-risk areas occurs, resulting in decreases in the tax base funding.

Decades of underinvestment, disinvestment, and unjust systems have contributed to outdated and deteriorating infrastructure, including schools, in low-income communities; communities of color; and indigenous communities and tribal nations. . . As a result, these communities often experience the impacts listed above more acutely than others. They also tend to have fewer resources to improve, let alone maintain and operate, their buildings and respond to climate events. They often then rely on temporary fixes while deferred maintenance needs grow, leading to higher costs in the long-term.  

Case study: Heat, children and school infrastructure in the San Joaquin Valley

California’s San Joaquin Valley, home to many of these communities, is one of the most impoverished regions in the state and one of the warmest too, with drastic increases in daytime and nighttime temperature projected over the 21st century. More children are at risk of heat-related illness here than the statewide average. UCS analyzed how rising heat stress levels would affect students’ opportunities for physical activity in this region as a case study of why climate-smart infrastructure is critical to protecting children from increasing dangerously hot days.

We found that rising temperatures would reduce the window of time that it is safe for these children to be active outdoors, potentially disrupting health-promoting activities like exercise, further interrupting everyday life, and reinforcing the critical need for reliable cooling and climate-safe infrastructure and school facilities.

High-risk versus low-risk children and exertional heat-related illness

Prolonged exposure to extreme heat can cause heat-related illnesses (heat cramps, heat exhaustion, and heat stroke), exacerbate chronic disease, and even lead to death. Children, especially infants, toddlers, and preschoolers, are among the most vulnerable populations. Pre-pubertal children are at increased risk too because they are typically less able to understand and act on their body’s cues that it is too hot, or that it is time to rehydrate. They also acclimatize to heat more slowly than older children and adults.

When temperature and humidity climb during extreme heat events, the body’s cooling mechanisms become less effective. The result can be heat-related illness and/or the exacerbation of pre-existing conditions, as shown in this graphic. Children are among the most vulnerable populations.

Certain conditions, such as obesity, sickle cell disease, diabetes, poor physical fitness, and heat acclimatization levels, cause some children to be more susceptible than others to heat-related illness during rigorous physical activity (or “exertional heat-related illness”). We refer to them as “high-risk children.” Children in the Valley have higher obesity rates and lower physical fitness levels than the statewide average. We include elementary- and middle-school aged children and unfit, unacclimatized, obese or otherwise high-risk adolescents in the “high-risk” group. Healthy, fit, and acclimatized adolescents who are low risk are referred to as “low-risk children.”

Overview of analytical approach

We used data from high-resolution climate models developed by Pierce, Cayan, and Dehann to calculate the median WBGT index for a historical period (1975-2005), midcentury (2035-2064) and late century (2070-2099) across the three emissions scenarios shown below (no action, slow action, and rapid action). The WBGT index is the most commonly used metric for exertional heat stress during military activities, physical labor, athletics, etc. It combines ambient temperature, relative humidity, solar radiation, and wind speed. The American College of Sports Medicine’s (ACSM) activity modification recommendations for specific WBGT values serve as the basis for setting WBGT index values for stopping outdoor physical activities for high-risk and low-risk children (86.1°F and 90.1°F WBGT, respectively). (These thresholds are meant to be illustrative, rather than a recommendation for a specific threshold for use in schools.) We estimated the number of days that WBGT index values would exceed these thresholds by midcentury and late century. Read the methodology and caveats for more information.

Significant increase in days when outdoor activity is unsafe

If heat-trapping emissions continue rising throughout the century (no action scenario), the days would increase significantly by mid- to late century that heat stress levels would warrant no outdoor activity for high-risk children during the warm season. The days would extend beyond the summer into the months of May and September. Historically, conditions crossed the high-risk threshold during a median of 1 to 17 days per year in the San Joaquin Valley (depending on location). In Fresno, for example, children would experience an increase from 10 days per year historically to 50 days by midcentury. About one-third of these days would occur during the school year.


Days with periods that are not safe for high-risk children to be active outdoors will increase from 1 to 17 days to 3 to 15 weeks by midcentury. Schools must be prepared for this warmer future since many of these additional days will occur during the school year.

By late century under a no action scenario, high-risk children in almost three-quarters of cities in the Valley would face a median of 50 or more days per year with unsafe periods to be very active outside. This threshold would be crossed in some cities roughly one-quarter of the year, including Merced, Madera, Fresno, Clovis, and Porterville. “(As described in the caveats for this analysis, these numbers may be underestimates.)

During these times, preventative measures, such as staying hydrated and cool, will be especially important for protecting children from dangerous heat and allowing them to remain active. Infrastructure for cooling, like air-conditioned buildings, the electricity grid, and ‘cooler’ landscapes, plays a key role but there is no comprehensive data for the state (or the nation) about which public school facilities have these characteristics. We do know however that even in hot inland places, like the San Joaquin Valley, some schools are still without functioning a/c.

Coaches and teachers may cancel recess, physical education classes, sports practices and competitions, and extracurricular activities until temperatures cool or move them inside, so long as schedules and space permit. Since nighttime temperatures would also rise, the window for safe exertion outdoors will inevitably narrow. More time indoors increases children’s exposure to poor indoor air quality, while higher outdoor temperatures can contribute to increased outdoor air pollution levels that are detrimental to students’ health.

Low-risk children represent  a fraction of the under-18-population in the Valley. The number of days crossing their WBGT threshold will increase but to a much smaller degree.

Rapid climate action would reduce number of unsafe days for children in San Joaquin Valley

The number of days above these thresholds by late century would shrink significantly if rapid action is taken to slash heat-trapping emissions. In Fresno, it would more than halve the median number of exceedance days for high-risk children from 91 days to 44 days, whereas in the slow action scenario, the median number of days would drop to 56 days. The number of dangerous days for low-risk children would decrease to under one week in most places.

The solution: climate-smart policies and infrastructure

While it is not possible or practical to avoid every negative effect of climate change, risks can be minimized by ensuring our schools are built (or retrofitted) to be climate-smart– resilient, low-carbon, and equitable. It is not just the buildings themselves, but the policies governing operations and activities that occur in them matter, too. The solutions below focus on addressing heat-related illness at schools, but many concepts can be applied to other climate-related impacts, like wildfires, droughts, and flooding. (Some other helpful sources for specific school policy and infrastructure recommendations include: flooding (here and here) and wildfires (here and here).)

  • Update and Adopt Heat Health Policy: Federal and state governments should support research to foster consensus among the health and scholastic communities on the most appropriate heat stress metric and data sources for protecting children during outdoor activity. (Many metrics, like WBGT and heat index, were designed for adults in hot, humid environments.) School districts are using inconsistent approaches. Those currently without policies should adopt one. In addition, teachers or other supervising adults—not just coaches—should be trained on the signs of heat-related illness and preventive measures.


  • Update Standards and Codes to be Heat-Resilient in Addition to Zero Carbon: State and local authorities should update school facility standards and codes to transform them from mini-heat islands into cooling islands with smaller carbon footprints.* Passive cooling, shade-providing tree canopy, green schoolyards, cool roofs, and improved building envelopes are just a few design options to reduce heat load and lower electricity use and energy bills. Distributed energy resources, renewable energy, and storage help keep schools’ HVAC on during power outages. These updates should consider other impacts like flooding as well (e.g., placing battery storage above the flood line/zone.) Zero Net Energy Schools, Green Ribbon Schools, and Collaborative for High Performance Schools programs serve as additional resources for low-carbon, resilient design options. California has specific initiatives related to each of these, and its building code, Title 24, mandates some shading and recommends cool roofs.


  • Increase Funding for Capital Improvements: All levels of Government should increase their financial support for retrofitting and modernizing existing schools to be climate-smart through public grants, tax incentives, loans, and other fiscal tools. School bonds should incorporate climate-smart criteria so that funds are spent wisely on projects that will continue providing key services in a warmer future; address existing inequities in school facilities in low-income communities, communities of color, and certain rural communities; and reduce carbon emissions. Here in California, roughly 30 percent of our more than 10,000 schools are more than 50 years old and ten percent are 70 years old.


  • Develop Inventory of Facilities: Each state should create a comprehensive public inventory of K-12 public school facility characteristics and conditions that includes regularly-updated information. This inventory would help state and local authorities, as well as other funders, target HVAC, efficiency, heat reduction investments, and other capital improvements to schools and communities with the most critical heat-related deficiencies. If the March 2020 school bond on the California ballot passes, creation of this inventory could be included in bond implementation.

Making the grade now and in the future

We owe it to our children (and their children) to provide safe and healthy educational environments where they can grow and thrive. The $38 billion funding gap per year illustrates how short we are falling, and recent events, like heat waves, floods, wildfires, and droughts, put an exclamation point on the need. Continued emissions of heat-trapping pollution, largely from the burning of fossil fuels, will only make these impacts more frequent, severe, and longer-lasting. We are failing our children if we don’t act now to: (1) drastically and quickly reduce emissions and (2) ensure school facilities and grounds, not to mention the communities they live in, will be climate-smart. Students already know this and are raising their voices. It’s time for us adults to not only listen, but to act.

The author would like to thank the following people for their review of the research and analysis: Dr. Andrew Grundstein, Dr. Yuri Hosokawa, Phoebe Seaton, JD, and Dr. Jeff Vincent. Dr. Owen Doherty and Dr. Pablo Ortiz assisted with WBGT calculations.

*Dr. Jennifer Vanos, personal communication