Celebrating Earth Day 2025 at the John Muir Historic Site in Martinez, CA on April 26th.

Earth Week would not be complete without the annual celebration of John Muir’s birthday at the site of his historic home, now a National Park in Martinez, CA. Earth Week Coordinator Sheila Kanodia was the first to arrive on site, where canopies, tables, and chairs were ready and waiting for dozens of community groups and local agencies that participate each year. Sheila and I set up displays and activities relating to this years CCEW theme, “Glaciers: Hot Topic, Cool Chemistry,” while Greti Séquin arranged her plant display, mystery scent samples, and molecular models. We also brought out the ever-popular UV-color-changing beads, and despite the gray skies and occasional threatening clouds, there was plenty of UV light to change the white beads to vivid colors.

By 10 AM we were joined by our first wave of volunteers, including Sheila’s friends Aparna and Reshma, Branden and Ajay from the Sigma Chapter of Alpha Chi Sigma at UC Berkeley, UCSF postdoc Sagar Bhattacharya, Dan Phillips of Saint Mary’s College, and several students from Diablo Valley College. The festival opened with the traditional procession, led by John Muir himself and a Scottish piper from the Piedmont Highlanders. Despite the threatening weather, we soon had a crowd of visitors who were ready to learn about glaciers, ice bergs, and sea level rise. The could compare the rate of ice-melting in warm or cold water, and observe that ice-water (dyed blue) sinks in warmer, fresh water (dyed yellow) but floats on top of sea water (3.5% salt, dyed red).

Kids were eager to make UV-detecting bracelets and necklaces, and many tried to identify the mysterious plant fragrances, and then learned about the molecular structure of terpene essential oils. Using plastic molecular models, they could build any structure, from simple ones such as acetic acid to complex terpenes such as vanillin or limonene.

The chilly weather may have discouraged some, but it was a full day of hands-on science for Cal ACS and hundreds of visitors. We couldn’t have done it without our enthusiastic volunteers — special thanks to Dr. Laura Burns at DVC for sending so many of her students to join us.