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Earth Notes: Why the Desert Smells Like Rain

A field of yellow flowers
Melissa Sevigny
/
KNAU
A poppy bloom in the Sonoran Desert

Four decades ago, naturalist and author Gary Paul Nabhan wrote a book called The Desert Smells Like Rain. The title came from the answer a young Tohono O’odham boy gave when asked what the desert smelled like to him.

The response captured the essence of the summer monsoon rains, when wet creosote fills the air with a delicious fragrance.

In new research, Nabhan and colleagues at the University of Arizona asked why the desert smells like rain.

They looked first at the earthy smell of soil crusts that cover desert landscapes. But their findings point more to volatile compounds emitted not only by creosote bush, but also at least sixty other plant species in the ironwood-giant cactus forest--such as brittlebush, ambrosias, and desert lavender.

Researchers identified more than a hundred volatile oils in leaves and flowers that blend together and give off a heady fragrance before, during, and after rainstorms. Combined, all these scents create the desert’s unique “osmocosm” or world of smell.

Plants evolved these complex chemicals to ward off dryness, heat, and herbivores. Ironically, these same compounds may have potential health benefits for people as they inhale and metabolize them—much like the phenomenon of forest bathing practiced by Japanese and Korean residents to ease the stresses of city life.

Gary Nabhan and colleagues are also designing public gardens in southern Arizona and Mexico, where residents and visitors can experience this overall sense of well being—just by taking a deep breath when it rains.

This Earth Note was written by Rose Houk and produced by KNAU and the Sustainable Communities Program at Northern Arizona University.

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