From inside her living room in London, Paula Koelemeijer can feel the world around her growing quieter.
Koelemeijer, a seismologist, has a miniature seismometer sitting on a concrete slab at the base of her first-floor fireplace. The apparatus, though smaller than a box of tissues, can sense all kinds of movement, from the rattle of trains on the tracks near Koelemeijer’s home to the waves of earthquakes rolling in from afar. Since the United Kingdom announced stricter social-distancing rules last month, telling residents not to leave their home except for essential reasons, the seismometer has registered a sharp decrease in the vibrations produced by human activity.
“It’s very literally reflecting a slowdown of our lives,” Koelemeijer told me over Skype.
Koelemeijer said she briefly geeked out over the recent data before reality set in. At first glance, this is indeed a fascinating observation, the kind of factoid that might appear on the underside of a Snapple cap. The “wow” moment is short-lived, of course, because the explanation is not a quirk of nature or some other benign eccentricity, but a catastrophic virus that has sickened and killed thousands, crumpled economies, and plunged public life into a fearful limbo with no easily discernible end.
But the response to the pandemic has unwittingly produced some other large-scale, though less conspicuous, effects. In a bittersweet twist, the surreal slowdown of life as we know it has presented researchers with a rare opportunity to study the modern world under some truly bizarre conditions, and they’re scrambling to collect as much data as they can. Here are four ways the pandemic is being felt across land, air, and sea.
There’s less rumbling on the surface
Seismologists around the world have noticed the same effect Koelemeijer detected in London, and at more traditional stations than a fireplace.
The trend started with Thomas Lecocq, a seismologist at the Royal Observatory of Belgium, in Brussels. Seismic stations are usually found well outside metropolitan areas, away from vibrations that could obscure subtle tremors within Earth’s interior, but the Brussels station was established more than a century ago, before a city grew around it. Today, it provides a fascinating glimpse of the ebb and flow of a bustling city; Lecocq has found that when it snows, anthropogenic seismic activity decreases, and on the day of a road race, it spikes. Lecocq checked seismic data the day before Belgium began a nationwide lockdown, and then the following morning. The drop in activity, he said, was “immediate.” Right now, daytime in Brussels resembles Christmas Day.
Lecocq shared his approach online, and seismologists in the United States, France, New Zealand, and elsewhere are now seeing the effects of their country’s own social-distancing measures on seismic activity. For seismologists who study seismic signals from Earth’s interior—rather than other sources, including people, animals, even storms—quarantines seem to have made it easier to listen. “Normally we wouldn’t pick up a 5.5 [magnitude earthquake] from the other side of the world, because it would be too noisy, but with less noise, our instrument is now able to pick up 5.5’s with much nicer signals during the day,” Koelemeijer said.
There’s Less Air Pollution
As cities and, in some cases, entire nations weather the pandemic under lockdown, Earth-observing satellites have detected a significant decrease in the concentration of a common air pollutant, nitrogen dioxide, which enters the atmosphere through emissions from cars, trucks, buses, and power plants. The drop, observed in China and Europe, coincided with stringent social-distancing measures on the ground. Air pollution can seriously damage human health, and the World Health Organization estimates that conditions stemming from exposure to ambient pollution—including stroke, heart disease, and respiratory illnesses—kill about 4.2 million people a year.
The cleaner air could lead to a brief respite in parts of the world with severe air pollution even as they battle the coronavirus. According to an analysis by Marshall Burke, a professor in Stanford’s Earth-system science department, a pandemic-related reduction in particulate matter in the atmosphere—the deadliest form of air pollution—likely saved the lives of 4,000 young children and 73,000 elderly adults in China over two months this year.
City Soundscapes Are Changing
With so many people staying home—and public-transit agencies cutting service as a result—there’s significantly less noise from cars, buses, trains, and other transportation. Erica Walker, a public-health researcher at Boston University, has taken a decibel meter with her on her socially distanced walks, and she has been stunned by the measurements. “It’s a lot quieter,” she told me.
Before the coronavirus pandemic, the acoustic environment in Kenmore Square, a busy intersection near campus, is usually about 90 decibels during rush hour. Yesterday, Walker’s rush-hour readings were just under 68 decibels. (For comparison, a subway train rumbling past nearby registers at 95 decibels—the level at which chronic exposure could result in impaired hearing—and the sound of normal conversation is 60 to 70 decibels.) In some spots in the Fenway Park area, where Walker has studied noise pollution for several years through her program Noise and the City, her latest data show reductions close to 30 decibels. “It’s unbelievably a huge difference,” Walker said.
City dwellers might now be hearing sounds that can get muffled by the usual drone. Rebecca Franks, an American who lives in Wuhan, the epicenter of the coronavirus outbreak in China, made this observation 48 days into the city’s quarantine last month: “I used to think there weren’t really birds in Wuhan, because you rarely saw them and never heard them. I now know they were just muted and crowded out by the traffic and people,” Franks wrote on Facebook. “All day long now I hear birds singing. It stops me in my tracks to hear the sound of their wings.” Sylvia Poggioli, an NPR correspondent in Italy, reported that the streets of Rome are so empty, “you can actually hear the squeak of rusty door hinges,” and “the chirping of birds, an early sign of spring, is almost too loud.”
A quick search for the phrase birds are louder on Twitter reveals that many other people have been wondering the same thing I have lately: Are the birds chirping more fiercely these days, or am I losing my mind? With spring migration in full swing in the Northern Hemisphere, there are certainly more birds around. But the reduction in noise pollution—and, in some places, its total absence—might make it easier to notice the usual trilling and squawking.
The Oceans Are Probably Quieter, Too
For other species, less noise pollution is no doubt welcome. Michelle Fournet, a marine ecologist at Cornell who studies acoustic environments, is hoping to position underwater microphones off the coast of Alaska and Florida, where she has studied humpback whales and other marine life, to investigate how the waters have changed in the absence of noise from cruise ships as the industry suspends operations worldwide.
“Just pulling those cruise ships out of the water is going to reduce the amount of global ocean noise almost instantaneously,” Fournet told me. “We’re experiencing an unprecedented pause in ocean noise that probably hasn’t been experienced in decades.”
Research has shown that ambient noise from ships and other maritime traffic can increase stress-hormone levels in marine creatures, which can affect their reproductive success. Whales have even shown they can adapt to the din, pausing their singing when cargo ships are near and resuming when they move away.
The unexpected ecological moment brought on by the pandemic reminds Fournet of an accidental experiment that unfolded in the days after 9/11, when ship traffic in North American waters ground to a halt. Researchers working in Canada’s Bay of Fundy—already making recordings and taking samples before the terrorist attacks—eventually found that over the course of just a few days, when the noisy waters calmed, right whales in the bay experienced a drop in their stress-level hormones.
Fournet is thinking now of North Pacific humpback whales, who have begun to move northward this month and will soon be swimming with newborn calves in southeast Alaska, a region also popular with cruise ships for views of local wildlife. “This will be the quietest entry that humpback whales have had in southeastern Alaska in decades,” Fournet said. “Nature is taking a breath when the rest of us are holding ours.”
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