Shrinking Tree Cover at California Schools Raises Health Issues

Tree Canopy Decline Across More Than 7,000 Campuses

A recent study of over 7,000 California public schools reveals a troubling trend: roughly 85% of campuses lost tree canopy between 2018 and 2022, with some losing more than 40% of their shade cover. Many of these schools already had low canopy to begin with, especially in heat-vulnerable regions.

This loss is significant. Trees provide shade, reduce surface temperatures, and help protect children from dangerous heat exposure during recess, physical education, and outdoor learning.

Heat Exposure and Child Health

Researchers found playground heat indexes reaching 120°F (49°C) in some areas. Without tree cover, asphalt and concrete absorb heat throughout the day, creating harsh microclimates that affect student comfort and safety. This has real consequences: reduced focus, increased dehydration risk, and limited outdoor activity during school hours.

As Arboreal Advocate Kevin Loewen often explains, canopy loss is not just an environmental issue—it’s a public-health issue. Shade is essential infrastructure, especially for young students who spend hours each day outdoors.

Why These Losses Are Happening

Several factors are driving the decline:

• Extreme heat and prolonged drought stress
• Aging or diseased trees not being replaced
• Budget constraints 
• Urban development limiting planting space

The study also shows that losses are worst in already under-shaded, low-income communities—amplifying existing inequities in environmental health.

Opportunities for Re-Greening Schoolyards

Despite the challenges, the path forward is clear. Increasing canopy on school campuses is one of the most effective ways to protect children from rising temperatures. Planting native, drought-tolerant trees; redesigning paved areas; and investing in long-term maintenance can dramatically improve schoolyard conditions.

For Kevin Loewen, these findings reinforce a core message: tree care and proactive planting are essential tools for climate resilience. Schools can—and should—be leaders in this work, creating shaded, healthy spaces for the next generation.