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.

Prof Bryan Pijanowski from Purdue University in the US has been listening to natural sounds for 40 years and taken recordings from virtually all of the world’s main types of ecosystems.

He said: “The sounds of the past that have been recorded and saved represent the sounds of species that might no longer be here – so that’s all we’ve got. The recordings that many of us have [are] of places that no longer exist, and we don’t even know what those species are. In that sense they are already acoustic fossils.”

Numerous studies are now documenting how natural soundscapes are changing, being disrupted and falling silent. A 2021 study in the journal Nature of 200,000 sites across North America and Europe found “pervasive loss of acoustic diversity and intensity of soundscapes across both continents over the past 25 years, driven by changes in species richness and abundance”. The authors added: “One of the fundamental pathways through which humans engage with nature is in chronic decline with potentially widespread implications for human health and wellbeing.”

The shift in ecosystem sound is happening in the air, the forests, the soil, and even under the water. During the cold war, the US navy used underwater surveillance systems to track Soviet submarines – and found they struggled to do so near coral reefs due to all the sounds reefs produced. It wasn’t until 1990 that civilian scientists could listen to this classified data.

“Whenever we went to a healthy reef it blew our minds – the cacophony of sounds we heard,” said Simpson, who has been monitoring coral reefs using hydrophones for more than 20 years. “A healthy reef was a carnival of sound.”

At the outset of his research, noise pollution from motorboats was his main concern, but 2015 and 2016 brought significant bleaching events, which resulted in 80% mortality of corals. “They cooked the reef,” he said. More than half of the world’s coral reef cover has now been lost since 1950. If global heating reaches 2C, more than 99% of coral reefs are expected to start dying.

The result of these bleaching events is a “deathly silence”, said Simpson. “We swam around those reefs crying into our masks.”

“These sounds and silences speak back to us like in a mirror,” said Hildegard Westerkamp, a Canadian sound ecologist who has been recording soundscapes for half a century, during which time wildlife populations have experienced average declines of almost 70%.

She started working on the World Soundscape Project in 1973 with the intention of documenting disappearing ecosystems. “We proposed to start to listen to the soundscape, to everything, no matter how uncomfortable it may be – how uncomfortable the message.”

She said: “The act of listening itself can be both comforting and highly unsettling. But most importantly it tends to connect us to the reality of what we are facing.”

Sound data is now being used alongside visual data as a way to monitor conservation efforts and ecosystem health. More sophisticated and cheaper recording equipment – as well as increasing concerns about environmental destruction – are driving the boom in ecoacoustic monitoring.

As the sophistication of microphones has increased, scientists are using them to monitor life that would not usually be audible to human ears. Marcus Maeder, an acoustic ecologist and sound artist from Switzerland, has been investigating the noises trees make under stress, pushing a microphone into the bark of a tree to listen to the living tissue. Stress sounds like pulses come from within the cavity, he said.

When he first pushed a microphone into the soil of a mountain meadow he discovered it was also alive with noise, “a completely new kingdom of sounds”.

Intensively managed agricultural land, often doused with pesticides, sounds very different, Maeder said: “The soil becomes quiet.”

For many researchers, disappearing soundscapes are a source of grief as well as of scientific interest. “It’s a sad thing to be doing, but it’s also helping me tell a story about the beauty of nature,” said Pijanowski. “As a scientist I have trouble explaining what biodiversity is, but if I play a recording and say what I’m talking about – these are the voices of this place. We can either work to preserve it or not.

“Sound is the most powerful trigger of emotions for humans. Acoustic memories are very strong too. I’m thinking about it as a scientist, but it’s hard not to be emotional.”

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The tale starts 30 years ago, when Bernie Krause made his first audio clip in Sugarloaf Ridge state park, 20 minutes’ drive from his house near San Francisco. He chose a spot near an old bigleaf maple. Many people loved this place: there was a creek and a scattering of picnic benches nearby.

As a soundscape recordist, Krause had travelled around the world listening to the planet. But in 1993 he turned his attention to what was happening on his doorstep. In his first recording, a stream of chortles, peeps and squeaks erupt from the animals that lived in the rich, scrubby habitat. His sensitive microphones captured the sounds of the creek, creatures rustling through undergrowth, and the songs of the spotted towhee, orange-crowned warbler, house wren and mourning dove.

Back then, Krause never thought of this as a form of data-gathering. He began recording ecosystem sounds simply because he found them beautiful and relaxing. Krause has ADHD and found no medication would work: “The only thing that relieved the anxiety was being out there and just listening to the soundscapes,” he says.

Inadvertently, he had begun to gather a rich trove of data. Over the next three decades he would return each April to the spot at the bigleaf maple, set his recorder down and wait to hear what it would reveal.

But in April last year, Krause played back his recording and was greeted with something he had not heard before: total silence. The recorder had run for its usual hour, but picked up no birdsong, no rush of water over stones, no beating wings. “I’ve got an hour of material with nothing, at the high point of spring,” says Krause. “What’s happening here is just a small indication of what’s happening almost everywhere on an even larger scale.”

A rich weave of sound fades

Animals produce a vast array of sounds: to find mates, protect territories, identify offspring or simply by moving about. But traditionally, ecologists have measured environmental health by looking at habitats rather than listening to them. Krause developed the idea that the sound of healthy ecosystems contained not only the calls of individual animals, but a dense, structured weave of sounds that he called the “biophony”.

In 2009, when Krause listened through his archive, he realised a story was emerging: a subtle but noticeable loss in the density and variety of natural sounds.

At the same time, he began observing odd things happening in Sugarloaf Ridge park. Leaves on some tree species were unfurling two weeks earlier than documented in historical records. The change in bloom meant migrating birds following the Pacific Flyway were out of sync with sources of food along their route. Winter rain patterns had changed. Then in 2012, exceptional drought conditions started. California had been getting little rain and record hot temperatures, which pushed the parched land into unprecedented territory.

By 2014, northern California was experiencing its most serious drought in 1,200 years, and the bird song in Krause’s recording becomes muted.

In 2015, the quiet sets in. There is no stream flow or wind in the audio. In 2016, the hush is broken only by the call of a purple finch.

“A great silence is spreading over the natural world even as the sound of man is becoming deafening,” Krause wrote in 2012, in his book The Great Animal Orchestra. “The sense of desolation extends beyond mere silence.”

Life swept away by fire

Then, in 2017, the Tubbs fire struck, the most destructive wildfire in northern California’s modern history.

Krause happened to be awake at 2.30am on the October morning when the flames reached his home. He and his wife had to run through a wall of fire surrounding the house. “Except for us, not one single item that we had amassed over the arc of our lives survived,” he says. “As we raced toward the car, a fire tornado seethed with a voice of rage.

“That sound haunts us to this day,” he says. “I rarely make it through a night without awakening to frightful sonic nightmares.”

Propelled by gusts of 78mph, the fire incinerated entire neighbourhoods. Krause’s cats, Seaweed and Barnacle, died. He lost 70 years of letters, photographs and field journals, in flames so intense they left the refrigerator an unrecognisable puddle of aluminium and steel. His precious recording archive survived, in copies stored elsewhere.

The Tubbs fire burned 80% of Sugarloaf Ridge park. John Roney, the park manager, managed to evacuate 50-60 campers as the fire roared towards them.

The bigleaf maple survived. It stood up to the fire,” says Breck Parkman, a retired state parks archaeologist. “It lost branches and got partially stunted, but it survived.” But in September 2020, the Glass fire hit: one of nearly 30 wildfires across California that month.

“That pretty much finished off what was left of that tree,” says Parkman. He remembers once taking Clint Eastwood to look at it, as well as some botanists trying to establish if it was the biggest maple in the American west – they never confirmed its status. “It didn’t really matter, though. The birds knew the tree was grand. For them, this was the tree of life,” he says.

He believes the tree should have lived for a few hundred more years and likens it to an elder at family gatherings who brings wonderful food. One day that person disappears. “It’s a type of sadness – it’s hard to describe,” he says.

“It’s a loss, and there’s a longing. I would suspect the birds still miss that tree. I do.”

Many forest ecosystems are reliant on fire to decompose dead wood and old leaves but historically these tended to be smaller fires. They did not typically burn the tree canopy, so insects and other animals could take refuge without getting scorched. The larger fires in recent years are much hotter and threaten endangered species that have restricted ranges.

Desirae Harp, an educator at the state park and member of the local Mishewal Wappo tribe, says the silence that fell after the fires broke her heart.

“Hearing that silence, of all those native plants and animals, is heartbreaking because those are our relatives. I feel like when human beings die we call it genocide. But when we destroy whole ecosystems, we don’t always understand the weight of that.”

A silent message to the world

One of the most significant environmental books of the 20th century is Silent Spring by Rachel Carson. Published in 1962, it warned that if people did not stop their destruction of nature, especially through the use of pesticides such as DDT, the number of birds and other wild creatures would continue to decline and silence would begin to fall over the natural world.

In Krause’s recording from April 2023, not only is the birdsong missing, but there is no water in the creek either. “We’re watching this in our own lifetime, which is startling,” he says.

Comparison of 2003 and 2023:

In 2019, Krause argued that the climate crisis could be “changing the Earth’s natural acoustic fabric”. He drew an analogy between the natural world and a concert hall: if the heat and moisture of the concert hall changed, so too would the players’ ability to perform.

“The same is happening for Earth’s orchestra. New atmospheric conditions are detuning natural sounds,” he wrote. “Only major mitigation actions will help preserve Earth’s beat.”

One of the reasons people were first drawn to Sonoma county, where most of the state park lies, was to go fishing, hunting and swim in the creeks. In the 1970s there were many places to swim, says Steven Lee, a research manager at Sonoma Ecology Center. “People don’t swim in the creeks here any more. Why not? Because there’s not enough water.”

The biodiversity associated with the streams has also been lost. Chinook salmon and steelhead trout are unable to reach their spawning grounds if there is no water. “It’s definitely drastic,” says Lee, about Krause’s latest recording. “The pessimist in me would say that we’re probably going to see a lot of these declines continue to happen.”

Waterways are critical lifelines for wildlife in dry places such as California, with a whole cascade of life depending on them. Droughts mean this lifeblood no longer flows through the landscape.

Caitlin Cornwall, a project manager at the Sonoma Ecology Center, says: “There is a direct link between reversing climate change and having more birds in Bernie’s recordings.

She calls Sugarloaf “a relatively mid-range example of what happens when you have an extreme drought”.

The drought is not the only pressure. Across the state, human activity is cutting into animal food sources and habitats. Wild places are being converted into farmland and urban areas, and invasive species are becoming more common. Some of the songbirds Krause captured in 1993, such as the orange-crowned warbler, are now in widespread decline.

Many of the birds captured in Krause’s recordings are migrant species “living on a knife-edge”, says Cornwall. “If a year’s cohorts have died in a particular place, then next year the young – and even the adults – might not come back.” It could take generations for them to recolonise a habitat – assuming they survive elsewhere.

Krause, who has been recording ecosystems from Africa to Latin America to Europe, says it is depressing to hear how the places he visits have changed. His personal library contains more than 5,000 hours of recordings, taken over 55 years from all over the world. He estimates that 70% of his archive is from habitats that have now disappeared.

“The changes are profound,” he says. “And they are happening everywhere.”

“I’ve got to this point in my life now where I just don’t know quite how to handle it, or how to express it, or what to say – yet I’ve got to tell people what I see and what I hear. Actually, I don’t need to say anything – the messages are revealed through the soundscapes.”

There have been some optimistic signs at Sugarloaf Ridge. Roney has 40 cameras around the park, which have taken 60,000 photos in the past five years. He says there are hopeful indications, such as black bears and mountain lions moving into the area. Krause is 85 now and says his hearing days are numbered: he is almost totally deaf in his right ear and has some hearing loss in his left. He can no longer hear subtle changes in sound like he used to. “That’s a loss that I quite regret but have learned to live with,” he says.

Still, he looks forward to spring and to his next recording in Sugarloaf Ridge. He is hopeful that this year there could be signs of a resurgence. “The stories conveyed through the voices of these critters will tell us all we need to know that’s worthwhile,” he says. “When we finally learn how to listen.”

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The UK faces food shortages and price rises as extreme weather linked to climate breakdown causes low yields on farms locally and abroad.

Record rainfall has meant farmers in many parts of the UK have been unable to plant crops such as potatoes, wheat and vegetables during the key spring season. Crops that have been planted are of poor quality, with some rotting in the ground.

The persistent wet weather has also meant a high mortality rate for lambs on the UK’s hills, while some dairy cows have been unable to be turned out on to grass, meaning they will produce less milk.

Agricultural groups have said the UK will be more reliant on imports, but similarly wet conditions in European countries such as France and Germany, as well as drought in Morocco, could mean there is less food to import. Economists have warned this could cause food inflation to rise, meaning higher prices at supermarkets.

Tom Bradshaw, the president of the National Farmers’ Union, said markets had “collapsed” as farmers fail to produce food in the punishing conditions. He said: “We’re going to be importing a lot more product this year.”

One major retailer said the wholesale price of potatoes was up 60% year on year as much of the crop had rotted in the ground.

Supplies of potatoes have also been affected by a 10% reduction in the area planted last year as farmers switched to less weather dependent and more financially secure crops. Industry insiders said they expected a further 5% fall in planting this year.

Jack Ward, chief executive of the British Growers Association, said: “There is a concern that we won’t ever have the volumes [of potatoes] we had in the past in the future.”

He said wholesale prices were too low for farmers to generate enough income to cope with high fuel, labour and machinery costs as well as the effects of climate breakdown. “We are not in a good position and it is 100% not sustainable.”

Supplies of carrots and parsnips, which are left in the ground and so also affected by sodden soils, are also much lower than usual, pushing up prices.

Martin Lines, the chief executive of Nature Friendly Farming Network, said: “The impact in the UK this year will significantly affect potatoes and the salad crop. Farmers are already facing delays in planting, with many fields in poor condition. If planting occurs at all, it will likely be late, potentially leading to a shortage of root vegetables and potatoes this coming winter.

“Some farmers have ceased planning for planting altogether, opting instead to put fields into fallow or switch to alternative crops. This could also result in shortages of wheat, barley and pulses as it’s currently unprofitable to grow these due to the lateness of the season and low forecasted prices.”

Guy Singh-Watson, the founder of the organic vegetable box company Riverford, said he had so far planted “virtually no veg”. “Some overgrown plants cannot wait any longer to go in the ground, and will have to be ditched.”

While retailers often turn to imports to fill gaps on shelves, farmers across Europe are enduring a similarly difficult start to the year, with difficulties developing winter crops and sowing spring crops.

France is experiencing the poorest start to its wheat-growing season since 2020 amid cold wet weather, while production of fruit and vegetables in Morocco is being affected by drought. Morocco’s second-largest reservoir has dried up, meaning irrigating crops will be difficult.

Amber Sawyer, an analyst at the Energy and Climate Intelligence Unit, said last year almost a third of the UK’s tomatoes, and more than two-thirds of its raspberries and brussels sprouts, came from Morocco.

“As climate change worsens, the threat to our food supply chains – both at home and overseas – will grow,” Sawyer said.

Scientists have said this is just the beginning of shocks to the food supply chain caused by climate breakdown and that without rapid action to drive down emissions by ceasing to burn fossil fuels, the current system is unsustainable.

Dr Paul Behrens, an associate professor of environmental change at Leiden University in the Netherlands, said: “We should all be extremely concerned. We need to be doing everything to reduce emissions while transforming our food systems.”

He added: “If we don’t … I expect huge turmoil and escalating prices in the next 10 to 20 years. When food prices spiral we always expect political instability. I wish people understood the urgent climate threat to our near-term food security.

“Fortunately, we know many ways we can make the food system more resilient while reducing food emissions. The biggest opportunity in high-income nations is a reduction in meat consumption and exploration of more plants in our diets.”