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20sci-climattesounds-jumbo

Art: Matt McCann
As the planet warms, say scientists, Earth’s creatures are having a harder time making noises needed for survival.

Today is the 50th anniversary of the first Earth Day. Are you old enough to remember what you were doing then? I was teaching sixth grade language arts in a Pennsylvania public school. The science teacher spearheaded our Earth Day and made sure everyone absorbed lessons about pollution.

Pollution was the biggest concern 50 years ago, says Denis Hayes, Earth Day founder. Global warming “was not part of the national discussion,” but that has changed, he adds.

Among the many climate-change topics I could highlight on this Earth Day, I found the altered soundscape of the natural world especially interesting.

Emily Anthes writes in the Science section of the New York Times, “Spring in Sugarloaf Ridge State Park, in Northern California, is typically a natural symphony. Streams whoosh, swollen with winter rains, and birds — robins, sparrows, grosbeaks, woodpeckers and hawks — trill and chatter.

“But in 2011, a yearslong drought set in. By spring 2015, a local creek had dried up and the valley had gone quiet. ‘The park went from an extremely vibrant habitat to one that was dead silent,’ said Bernie Krause, a soundscape ecologist who has been recording in the park since 1993.

‘Nothing was singing, nothing was chirping, nothing was moving. It’s like it was dead.’

“In the coming years, severe droughts are likely to become more common; as the water dries up, bird song could disappear along with it. It is just one example of how climate change may be altering the planet’s soundscapes, or ‘breaking Earth’s beat,’ as Dr. Krause and his colleagues put it in a paper last year. Dr. Krause, who has amassed more than 5,000 hours of natural recordings for his company, Wild Sanctuary, wrote the paper with Jérôme Sueur, an ecoacoustician at the French National Museum of Natural History in Paris, and Almo Farina, an ecologist at the University of Urbino in Italy.

“Climate change will silence some species and nudge others into new habits and habitats, changing when and where they sing, squeak, whistle, bellow or bleat. (In New York, several species of frogs now begin croaking nearly two weeks earlier in the spring than they did a century ago.) It will also alter the sounds that animals produce, as well as how such vocalizations travel.

“These shifts could make it more difficult for wild creatures to attract mates, avoid predators and stay oriented, as well as force them to expend more energy to make themselves heard. …

“Snapping shrimp are some of the noisiest creatures in the ocean. By rapidly closing their large claws, the animals make snaps, crackles and pops loud enough to stun prey into submission. But ocean acidification, which occurs as seawater absorbs rising levels of carbon dioxide, could soften their snaps. … Researchers at Australia’s University of Adelaide found that the shrimp snap less often and at lower volumes when the water becomes more acidic. …

“ ‘It’s not that ocean acidification completely takes away their ability to make loud snaps,’ said Ivan Nagelkerken, a marine biologist who led the study. ‘They can still do that but essentially don’t want to do that any more.’ [Meanwhile] many marine organisms, especially fish larvae, rely on the sound of snapping shrimp to navigate to suitable habitats.”

Other sound research is on the birds of northern Denmark. “In spring 2010, they were singing from positions nearly four feet higher above the ground than in the late 1980s, Anders Moller, an ecologist at the French National Center for Scientific Research, found.

“Dr. Moller suspects that climate-related changes in vegetation could be responsible. Over the last several decades, the spring and summer temperatures in the region rose 20 percent and precipitation increased 30 percent, he found, and other research has demonstrated that spring is arriving earlier than it used to across much of Europe.

“Foliage can interfere with the transmission of bird songs. If trees are leafing out earlier, or the vegetation is denser, birds might seek higher song posts to avoid this interference, Dr. Moller suggested. He found that species that breed in the forest increased their singing height more than those who mate in more open habitats, like grasslands.

But sitting higher in the trees could come with costs, too. ‘A bird that sits more exposed will run a higher risk of being captured by a sparrow hawk,’ Dr. Moller said.

“Climate change will bring extreme weather, including more frequent and intense storms, to many places on the planet. This uptick in wind and rain could drown out animal calls. … King penguins, which rely on acoustic cues to find their mates and chicks in crowded colonies, … cannot fully counteract the noise, and it takes them longer to find their mates when the wind is howling.”

Lots of other curious tidbits about changing soundscapes here.

Are you doing anything particular for Earth Day? Before lockdown, I was thinking of joining a demonstration against fossil fuel expansion, Stop the Money Pipeline. Instead I’ll probably donate to that, the Arbor Day Foundation, or the highly rated Eden Reforestation Projects. Bad air quality has made coronavirus more deadly, and trees remove pollutants.

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