Humans Are Changing How Nature Smells, With Risks for Wildlife

Across the globe, human activities are changing the way our planet smells. In Egypt, rising temperatures are shrinking the yields of aromatic jasmine flowers. In France, extreme drought has reduced the production of fragrant, night-blooming tuberose, a key ingredient in many perfumes. In Italy, climate extremes are altering the characteristic floral, citrusy scent of bergamot.

But these changes are not just about losing specific scents. Human activities are also reshaping environmental smellscapes. This term, coined in the 1980s, describes the total collection of scents in a given geographic area. These changes are far more subtle than missing flowers, but they may be much more harmful to the natural world.

Humans largely rely on sight and sound to interact with each other and with the world. Many other creatures rely heavily on smells. Ants require scents for colony cohesion. Turkey vultlets use scent to guide them to distant carrion. Male moths use scent to find females hundreds of meters away.

“Scent is very important because it mediates so many interactions within an ecosystem,” says James Blande, a chemical ecologist at the University of Eastern Finland. These scent-based interactions are crucial for ecosystem services that directly benefit humans. Bees and moths pollinate crops. Flies and dung beetles recycle nutrients from dead and decomposing matter.

Intact channels of scent communication are also important for preserving biodiversity. Many rare orchid species use scent to attract the co-evolved pollinators they need to reproduce. Scent helps guide monarch butterflies to the single type of plant on which they lay their eggs.