California schools Face Increasing Heat as Tree Canopy Declines
A recent study from UC Davis’s Urban Science Lab reveals a concerning trend: California school districts are experiencing a decline in tree canopy cover, leaving students increasingly exposed to extreme heat. Between 2018 and 2022, the average tree canopy loss across urban school districts was less than 2%, but some areas, notably in the Central Valley, saw considerably higher reductions - up to 25% in some cases. Tulare County experienced the most considerable losses, while Imperial County showed gains.
The research, a collaborative effort between UC Davis, UC Berkeley, and UCLA, highlights the vulnerability of California’s students to rising temperatures exacerbated by climate change. The study is funded by the U.S. Forest Service and supported by Green Schoolyards America’s California Schoolyard Tree Canopy study.
Researchers, led by Alessandro Ossola, an associate professor of plant sciences at UC Davis who directs the Urban Science Lab, are actively measuring the impact of this loss.They are assessing the extent to which high temperatures are impacting students’ well-being. This past summer, the team measured tree canopies and maximum temperatures at playgrounds, basketball courts, soccer fields, and other outdoor spaces at elementary schools statewide.
Currently,tree canopies cover only 4% to 6% of the average California school campus. This leaves approximately 5.8 million K-12 public school students exposed to direct sunlight during breaks and outdoor activities. Researchers mapped tree cover and heat fluctuations throughout the day at schools in both inland and coastal regions of Northern and Southern California, utilizing a mobile sensor cart named MaRTyna to gather data on mean radiant temperature and other key metrics.
“Most schools are actually a nature desert,” ossola stated, emphasizing the importance of nature exposure for children’s development, including skill-building, microbiome health, and environmental awareness. “Trees are a hidden asset and an underutilized asset.”
The study underscores the urgent need to increase tree canopy in schools with limited shade and to protect existing trees in areas experiencing loss, particularly as extreme heat and drought conditions are expected to intensify with climate change.
This report is adapted from a feature story published by the UC Davis College of Agricultural and Environmental Sciences: “Researchers Measure Schoolyard Heat One Step at a Time”.
