Loss of intensity and diversity of noises in ecosystems reflects an alarming decline in healthy biodiversity, say sound ecologists
Sounds of the natural world are rapidly falling silent and will become “acoustic fossils” without urgent action to halt environmental destruction, international experts have warned.
As technology develops, sound has become an increasingly important way of measuring the health and biodiversity of ecosystems: our forests, soils and oceans all produce their own acoustic signatures. Scientists who use ecoacoustics to measure habitats and species say that quiet is falling across thousands of habitats, as the planet witnesses extraordinary losses in the density and variety of species. Disappearing or losing volume along with them are many familiar sounds: the morning calls of birds, rustle of mammals through undergrowth and summer hum of insects.
Today, tuning into some ecosystems reveals a “deathly silence”, said Prof Steve Simpson from the University of Bristol. “It is that race against time – we’ve only just discovered that they make such sounds, and yet we hear the sound disappearing.”
“The changes are profound. And they are happening everywhere,” said US soundscape recordist Bernie Krause, who has taken more than 5,000 hours of recordings from seven continents over the past 55 years. He estimates that 70% of his archive is from habitats that no longer exist.
That had always been my assumption, but after looking more closely at the history of previous mass extinctions I’m not convinced that a near 100% extinction is unthinkable. It’s not just the number of species in the initial die-off, it’s the cascade of further extinctions caused by ecosystem collapse and the tenuousness of the eventual recoveries. Those recoveries often involve the recolonization of devastated regions from local ecosystems that survived relatively unscathed—but with the global spread of introduced species and the resulting homogenization of ecosystems, there won’t be as many sources of potential recolonization.
Pretty much all life on earth is now dependent on a host of other species to survive—even simple plants at the base of the food chain are dependent on microbes to extract nutrients from the soil and pollinators to reproduce. There are some bacteria that could probably survive just about anything, but it took bacteria over a billion years to evolve into anything more complex so there’s no guarantee they’d do it a second time.