New story in Science and Health from Time: NASA Astronaut and 2 Russians Blast Off for International Space Station NASA Astronaut and 2 Russians Blast Off for International Space Station

(MOSCOW) — A U.S.-Russian space crew blasted off to the International Space Station on Thursday following a tight quarantine amid the coronavirus pandemic.

NASA astronaut Chris Cassidy and Roscosmos’ Anatoly Ivanishin and Ivan Vagner lifted off as scheduled at 1:05 PM (0805 GMT) from the Russian-operated Baikonur cosmodrome in Kazakhstan. Their Soyuz MS-16 spacecraft is set to dock at the station at the station six hours later.

Russian space officials have taken extra precautions to protect the crew during training and pre-flight preparations as the coronavirus outbreak has swept the world.

Speaking to journalists Wednesday in a video link from Baikonur, Cassidy said the crew has been in “a very strict quarantine” for the past month and so in good health.

“We all feel fantastic,” he said.

New story in Science and Health from Time: Want to Stop the Next Pandemic? Start Protecting Wildlife Habitats Want to Stop the Next Pandemic? Start Protecting Wildlife Habitats

(Bloomberg) — There are four critical facets of pandemic prevention, according to Lee Hannah, senior scientist at Conservation International. Three of them make immediate sense against the backdrop of our current emergency: stockpile masks and respirators; have testing infrastructure ready; and ban the global wildlife trade, including the open animal markets where COVID-19 may have first infected people.

His fourth recommendation is more grandiose: “Take care of nature.”

The assault on ecosystems that allowed COVID-19 to jump from animals to humans went far beyond merchants hunting and selling rare wildlife. Biodiversity—that is, the health of the entire ecosystem—can restrain pathogens before they ever leave the wild. “We need to tell people right now that there is a series of things we need to do once we’re out of this mess to make sure it never happens again,” Hannah says.

Read more: Don’t Blame China. The Next Pandemic Could Come From Anywhere

The role of biodiversity in disease prevention has received increased attention of late. In a 2015 “state of knowledge review” of biodiversity and human health by the United Nations, scientists wrote that “an ecological approach to disease, rather than a simplistic ‘one germ, one disease’ approach, will provide a richer understanding of disease-related outcomes.” Recent research has given more support to the idea that biodiversity protection in one part of the world can prevent novel diseases from emerging and leaping into another.

It’s a numbers game, in part. Not all species in a community are equally susceptible to a given disease, nor are they all equally efficient transmitters. In diverse ecosystems well separated from human habitations, viruses ebb and flow without ever having a chance to make it to the big time.

But as people move in, those protections begin to break down. Disrupted ecosystems tend to lose their biggest predators first, and what they leave behind are smaller critters that live fast, reproduce in large numbers, and have immune systems more capable of carrying disease without succumbing to it. When there are only a few species left, they’re good at carrying disease, and they thrive near people, there may be nothing between a deadly pathogen and all of humanity.

“Virus spillover risk” from wildlife to people rises as contact increases between them, according to research published Tuesday by a team of researchers led by Christine Kreuder Johnson of the One Health Institute at University of California, Davis. Almost half of the new diseases that jumped from animals to humans (called zoonotic pathogens) after 1940 can be traced to changes in land use, agriculture, or wildlife hunting. SARS, Ebola, West Nile, Lyme, MERS, and others all fit the profile. There may be 10,000 mammalian viruses potentially dangerous to people.

“We are messing with natural systems in certain ways that can make them much more dangerous than they would otherwise be,” says Richard Ostfeld, a disease ecologist at the Cary Institute of Ecosystem Studies. “And biodiversity loss is one of those. Climate change is another.”

Read more: The World Is Not Ready for the Next Pandemic

A longer-term strategy can help nations see the benefits of rethinking resource use. “The revenue from clearing new forest is extremely high—briefly,” says William Karesh, executive vice president at EcoHealth Alliance, a research nonprofit. “But the cost to the public-health system also goes up because you get very common diseases like malaria.” And as we’re now seeing, new zoonotic pathogens can be even more expensive to deal with.

Despite years of creative and resource-intensive work by governments and nonprofits, companies’ actions to mitigate habitat loss aren’t adding up. Many large companies have pledged to halt deforestation, the largest driver of biodiversity loss, through initiatives like the Consumer Goods Forum, the Banking Environment Initiative and their Soft Commodities Compact. “All have missed the mark,” according to a new report by the Rainforest Action Network.

Hannah, of Conservation International, is working to make sure that the reasons to promote biodiversity, including its pathogen-dulling potential, align with the other endangered elephant in the room: climate change.

In February, Hannah and colleagues announced findings on what the effects of achieving climate and conservation targets might be. Using data on 290,000 species, they were able to squint into the future and see where ecosystems might be saved from mass extinction if nations preserve 30% of natural habitats and meet UN limits for global warming. All told, meeting the goals would cut biodiversity losses in half.

The international community is positioned to make some progress. The Convention on Biological Diversity is a 196-nation effort to protect the richness of living things, tap natural resources sustainably, and share the benefits of the environment’s naturally occurring genetic innovations. (The U.S. and the Vatican are non-members.) The next phase of the biodiversity treaty, currently in draft form, proposes that at least 30% of land and ocean be conserved, up from 17% in the previous round. If governments agree to that goal, then nations and conservation scientists must take on the complicated step of figuring out which 30% is most important to protect and how to do it.

The way those areas are drawn today rarely reflects the scientific ideal of how to guard biodiversity. Looking at the existing protected lands, a paper in Nature last month found that 90% of conservation space fails to give bird, amphibian and mammal species the full range of environmental conditions across their existing habitats.

“We could be doing a much better job of getting things in the right places,” says Hannah. “There’s going to be right places for disease control and they may largely overlap the right places for biodiversity.”

New story in Science and Health from Time: Your Pets Are Not Likely To Get or Transmit Coronavirus. Here’s What The Experts Say Your Pets Are Not Likely To Get or Transmit Coronavirus. Here’s What The Experts Say

This weekend a tiger at the Bronx Zoo tested positive for SARS-CoV-2, the virus that causes COVID-19 in humans. But it’s a leap to worry if your household feline can get or transmit the coronavirus, says Karen Terio, chief of the Zoological Pathology Program at the University of Illinois’ College of Veterinary Medicine, which assisted in diagnosing the tiger.

“A tiger is not a domestic cat, they are a completely different species of cats,” she says. “To date we have no evidence of the virus being transmitted from a pet to their owners. It’s much, much more likely that an owner could potentially transmit it to their pet.”

Even then, the risk of a pet contracting the virus is low. Globally, only two dogs and two cats have tested positive for the virus, according to the American Veterinary Medical Association (AVMA).

The first publicly recorded instance of a pet diagnosed with COVID-19 happened in Hong Kong in late February, and Hong Kong’s Agriculture, Fisheries and Conservation Department along with veterinary experts at the World Organization for Animal Health (OIE) concluded it to be a case of human-to-animal transmission. The pet dog belonged to someone who had the virus, and authorities at the Hong Kong Agriculture Department and OIE believe the dog contracted the virus from its owner.

“Over 1 million human cases at this point worldwide and we’ve only seen four domestic animals test positive so far worldwide, so the risk is very minimal [for COVID-19] to get to pets,” says William Sander, assistant professor of preventive medicine and public health, also at the University of Illinois’ College of Veterinary Medicine.

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Can your pet transmit the virus to you?

At the moment, Sander says, it appears there’s little-to-no risk of pets transmitting the virus to their human owners, with no specific evidence suggesting this type of transmission has ever happened. “That’s why in the U.S. we’re really not pushing hard to test pets at all,” he says. In the U.S., there hasn’t been a single case of a pet diagnosed with the virus, at least according to the country’s Centers for Disease Control and Prevention (CDC).

“There is no reason to think that animals, including pets, in the United States might be a source of infection with the coronavirus that causes COVID-19,” a spokesperson for the AVMA wrote in an emailed statement to TIME. “COVID-19 appears to be primarily transmitted by contact with an infected person’s bodily secretions, such as saliva or mucus droplets in a cough or sneeze.”

Terio, however, emphasizes that there is still much that is unknown. If your pet, for example, did contract the virus, it is not clear whether your animal would show signs of infection the way a human would. The tiger at the Bronx Zoo did show signs of respiratory distress, Terio says, “but there’s a lot that we don’t know about how different animals are going to respond to a viral infection.”

We don’t know if an animal could be an asymptomatic carrier, or if they’d experience a mild or severe form of the disease, Terio adds. “This is the tip of, you know, just trying to figure out what’s going on,” she says. “Unfortunately there are way more questions than answers at this time, and that’s tough…I think this whole thing is unsettling for everybody, and it’s hard when we don’t have good answers for people.”

Out of caution, the CDC and AVMA recommend that sick humans stay away from their animal companions. “Just like you’re keeping your distance from other people, try to have somebody else in your house take care of your pet, just to be overly cautious,” Sander says. If you are sick or showing symptoms and you have to take care of your pet, the CDC recommends avoiding snuggles or touching your pet, and washing your hands thoroughly before and after feeding.

Sander and Terio note that scientists still don’t fully understand how viruses like the one that causes COVID-19 might or might not move between humans and domestic animals.

Several preliminary studies, which have not been peer reviewed yet, have been shared on public access websites in the last week, Sander says, suggesting that some groups of domestic animals can be infected with SARS-CoV-2 in laboratory settings. Similarly, during the 2003 outbreak of SARS-CoV, also caused by a coronavirus in the same family as SARS-CoV-2, researchers determined that cats and ferrets could be infected with the virus—but that was in a lab setting. Those studies determined that there was little cause for concern that transmission—either to humans or to other animals—could happen in a natural environment, Sander says.

To understand SARS-CoV-2, “we base some of our educated guesses on the previous SARS-CoV that came out in 2003,” Sander says. As of now, researchers believe SARS-CoV-2, like the previous SARS, is not likely to transmit from pets to humans.

The AVMA also cautions against over-interpreting the results described in more recent studies, “some of which may report on data from a very small number of animals or provide only preliminary results.”

Can the virus live on fur?

Though studies have shown that the virus can live on a variety of surfaces for several hours or days, both Sander and the AVMA say it is unlikely the virus can live on an animal’s fur, though Terio notes that there isn’t enough research to say that with 100% certainty.

According to a study published in the New England Journal of Medicine, SARS-CoV-2 can live on plastics for 72 hours, on stainless steel for 48 hours, on cardboard for 24 hours and on copper for 4 hours.

“Obviously, pet fur was not one of the [surfaces] they tested,” Terio says. “There are a number of variables involved, but you have the presume that [the virus] could potentially survive for a period of time—of potentially a day or so on the surface. Again, we don’t know the answer.”

In its emailed statement, the AVMA spokesperson writes that while the virus can be transmitted by touching a contaminated surface or object and then touching your nose, mouth or eyes, “this appears to be a secondary route. In addition, smooth, non-porous surfaces such as countertops and doorknobs transmit viruses better than porous materials; because your pet’s hair is porous and also fibrous, it is very unlikely that you would contract COVID-19 by petting or playing with your pet. However, it’s always a good idea to practice good hygiene around animals, including washing your hands before and after interacting with them.”

The bottom line

Though there remain a lot of unknowns, the experts TIME spoke with agree that it is unlikely that a pet can be infected with the virus or that a pet can transmit the virus to humans. But if you are sick, take extra precautions around your animals, because there is a small chance they could catch the virus from you.

“In this time of social isolation, pets are actually a great comfort for the mental health side of things too,” Sander says. “If you aren’t showing any clinical signs of anything, take advantage of having that mental support.”

New story in Science and Health from Time: The Surprisingly Long History of the Ventilator, the Machine You Never Want to Need The Surprisingly Long History of the Ventilator, the Machine You Never Want to Need

With millions of people across the U.S. and the world battling COVID-19 infections, many of them struggling to breathe, ventilators have become a top priority for the health-care workers trying desperately to keep patients alive. And those machines, which help patients breathe or breathe for them, are in startlingly short supply.

For doctors, resorting to a ventilator is an extreme measure, used when a patient’s lungs cannot supply enough oxygen on their own. Ventilators can also give a patient’s body time to rest when breathing is difficult, and allow doctors to more easily remove lung secretions or deliver medications directly to the respiratory system.

Such treatments have rarely been more important to global public health—something that’s all the more striking given the surprisingly long history of the ventilator. While modern computer-controlled ventilators are relatively new, the basic principles on which they operate are more than a century old. The story of these machines, a history of incremental advances from dozens of doctors and technicians around the world, parallels broader historical developments in medicine and precision engineering.

While references to artificial ventilation can be found in passages from the Bible, some of the earliest attempts to use mechanical means to ventilate a patient—to breath for that person—can be traced back to the late 18th century, when the Royal Humane Society of England began supporting the use of bellows, akin to those used by blacksmiths at the time, as the best means of artificial respiration.

Such techniques could not be controlled effectively, but they demonstrated one of the main techniques of breathing for someone else: forcing air directly into the lungs. This system is known as positive-pressure ventilation. Another early attempt—an airtight box developed by a Scottish doctor in the 1830s, into which air could be rhythmically pumped to rescue a “drowned seaman”—demonstrated the other technique, negative-pressure ventilation. Rather than pushing air into the respiratory system, this system changes the air pressure of the environment outside the body. Because the pressure wants to equalize across the respiratory system and the atmosphere, those changes indirectly force air into and out of the lungs.

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Many early versions of a ventilator relied on this negative-pressure principle. In the late 19th century, a Viennese doctor developed an infant resuscitator box, which was reportedly used successfully. Famed inventor Alexander Graham Bell even took a crack at the problem of artificial respiration, developing a “vacuum jacket” with some success.

One of the most widely used ventilation devices of the first part of the 20th century, the iron lung, also used negative-pressure techniques. Developed in the 1920s, the iron lung became a standby in ICU treatment for children suffering from polio, a viral disease that could cause life-threatening paralysis, including of the respiratory muscles. Before a vaccine nearly eradicated the disease in industrialized countries in the late 1950s, polio epidemics were a nearly annual terror, striking thousands of victims, predominantly children. In 1952 alone, more than 3,000 children died from the virus. The iron lung, which worked by changing the pressure inside an airtight container, expanding and contracting the chest and pulling air in and out of the lungs, became a essential treatment.

Getty ImagesAn iron lung at St. Bartholomews Hospital. London. About 1935.

And yet, even as the iron lung became a symbol of what medicine could achieve, developments in positive pressure ventilation ensured that the device’s days were numbered as the most widely-used method of helping people breathe.

The Pulmotor, an early device for positive pressure ventilation, was introduced in 1907 by German businessman and inventor Johann Heinrich Dräger and his son Bernhard. The Pulmotor was a transportable device that disbursed oxygen through a face mask until a set pressure was reached in the lungs, at which point it switched to exhalation. Another early 20th century device called a “rhythmic inflation apparatus” pumped air into a sealed box around a patient’s head.

DrägerThe Pulmoter

By the 1960s, the medical establishment had followed in those footsteps—thanks in part to the development of new positive-pressure breathing devices for pilots of late-WWII era jet planes, who needed oxygen for their flights at high altitudes. One such medical device, known as the Bird Mark 7 Respirator, was developed in the mid-1950s by Forrest Bird, a former U.S. Army pilot who had worked on aviation breathing apparatuses and anti-g-force suits.

Getty ImagesTwo aviation cadets from Brooks Field wearing oxygen masks as they pilot a B-25 bomber on a routine high altitude training mission, Fort Worth, Texas, June 1944.

Some consider the Mark 7 to be the first modern medical respirator, though in the decades since there have been many advances in ventilator design, including better control facilitated by computers. Perhaps equally important were new advances in medical knowledge, through which physicians have learned a great deal about improving survival for patients on ventilator support. For example, one such study in 2000 changed prevailing notions about how much air should be forced into patients’ lungs in each breath, a measurement known as tidal volume. The paper demonstrated significantly higher survival rates when physicians lowered the volume of air their machines were using.

“That has now, of course, become the standard of care,” says Dr. James Stoller, a Professor of Emphysema Research at the Cleveland Clinic Lerner College of Medicine. “The ideal care of patients who develop ARDS [Acute Respiratory Distress Syndrome] from coronavirus would be to use this low tidal volume approach.”

Invasive ventilation—which uses an endotracheal or tracheotomy tube to help people breathe, rather than an external device like a mask—is still a last resort for particularly sick patients, and they are usually sedated to help them tolerate the process. “You or I talking would not allow anybody to do this to you, I can tell you,” says Laurie Ann Ferguson, interim dean of the College of Nursing and Health at Loyola University New Orleans. The sedation is partially meant to suppress the gag reflex, she says, which would be overwhelming if a patient were conscious.

Still, decades of steady improvement in ventilator design and refined knowledge among physicians of how to use them effectively have gone a long way in improving outcomes when doctors have to resort to breathing machines. And the culmination of those hundreds of incremental advances has never been more essential for so many.

“I can tell you that the protocols that are being developed for coronavirus…completely depend upon the insights and wisdom that have come from the last 20 to 30 years of science and systematic study,” says Stoller. Those protocols, he says, “are in use right now, this very minute.”

New story in Science and Health from Time: This Week’s ‘Supermoon’ Will Be Closer to Earth Than Usual—But at Roughly 220,000 Miles Away, It’s Still Appropriately Socially Distanced This Week’s ‘Supermoon’ Will Be Closer to Earth Than Usual—But at Roughly 220,000 Miles Away, It’s Still Appropriately Socially Distanced

(CAPE CANAVERAL, Fla.) — A supermoon rises in the sky this week, looking to be the biggest and brightest of the year.

Not only will the moon be closer to Earth than usual, it will also be a full moon. Scientists call this cosmic combo a supermoon. The moon will be 221,855 miles (357,042 kilometers) away at its fullest Tuesday night, making it appear larger and more brilliant.

NASA is encouraging everyone to look skyward, whether it’s outside or through a living room window.

Scientist Noah Petro of NASA’s Goddard Space Flight Center in Maryland said the important thing is to stay safe while moon-gazing during the pandemic. “If you can’t get out safely … then fine,” Petro said. “Go out next month or whenever it’s safe again. Use the full moon as an excuse to get out and start looking at the moon.”

He added: “Use this as an opportunity to not physically distance yourself, but emotionally connect with something that is physically far from us.”

There’s a string of supermoons this spring. So if you miss the upcoming lunar show, catch the next one May 7. In mid-April, the waning moon will pass by Saturn, Jupiter and Mars, clustered in the southeastern sky before dawn.

All this comes after a brilliant Venus passed a few days ago in front of the Pleiades, the so-called Seven Sisters star cluster.

“We’ve really been fortunate to have some good astronomy — backyard astronomy or living room astronomy,” Petro said.

New story in Science and Health from Time: Pausing the World to Fight Coronavirus Has Carbon Emissions Down—But True Climate Success Looks Like More Action, Not Less Pausing the World to Fight Coronavirus Has Carbon Emissions Down—But True Climate Success Looks Like More Action, Not Less

Runaway exponential growth. Unprecedented economic impacts. Untold deaths and suffering, especially among the poor and vulnerable.

All these superlatives are sadly apt descriptors for the COVID-19 crisis unfolding in front of our eyes. They also apply to climate change. But while the slowdown in activity due to COVID-19 has led to a temporary fall in China’s carbon dioxide emissions by up to a quarter, that’s not a fact worth celebrating. Nothing in this current crisis looks remotely like success.

When it comes to climate change, the relentless rise in global temperatures is but one harbinger of what is to come, and what is already happening all around. Fires burn brighter, longer and more often. Tropical cyclones grow stronger. There are more extreme heat days causing immense costs in lives and livelihoods alike. These weather extremes, meanwhile, are nothing compared to the consequences of a planet warmed by another degree or two Celsius. That, of course, is precisely why climate change is such a difficult problem to wrap our minds around and, ultimately, to address. The worst is yet to come—decades or even centuries hence.

COVID-19, by comparison, operates on an extremely compressed timescale. Decades are days, centuries are weeks. Political decisions from February—or the lack thereof—affect lives this month. Last week’s decisions affect this week’s case count. People are dying today, and many more will do so literally tomorrow.

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That means we should be looking for any key lessons and insights from decades of studying climate change that can make a difference now—such as include an understanding of exponential growth, the difficulty of dealing with uncertainty and how it takes government policy to address this kind of problem. But though the two crises mirror each other in several ways, the reverse idea, that we should learn from COVID-19 when it comes to the climate, is not necessarily true. Our efforts to mitigate disease transmission right now—such as shelter-in-place orders and limits on travel—should not be a future guide for mitigating carbon dioxide emissions. It would behoove anyone claiming otherwise to realize that most of the rest of us will not look fondly upon this current period of social and economic malaise.

If this were what climate success looked like, I wouldn’t want to vote for it. I care about climate change because I care about people, and people are dying right now. Thankfully, true climate success isn’t anything like today’s situation—even if emissions are down.

Successfully mitigating emissions implies the rapid deployment of new, clean technologies, not a collapse of the global supply chain. It implies more investment, not less.

The current $2.2 trillion spending bill rightly focuses on immediate relief. But more relief will surely be needed, and forthcoming government stimuli the world over ought to help guide the economy toward a more just and sustainable future. Wish lists are appropriately long. There is no single silver bullet—but there are some overarching principles, such as avoiding a further lock-in of inefficient high-carbon assets.

Using this crisis as an excuse to relax rules for polluters is more than just a step backward on the air pollution front. Polluted air compromises immune systems. Intact immune systems, meanwhile, are an important defense against COVID-19. (This, in fact, is one of the very few true silver linings to come out of the pandemic: decreased air pollution has immediate public health benefits, even if they are only temporary side effects of frozen economic activity.) But the answer to pollution isn’t to stop all activity; it’s to find ways to live our lives that don’t harm the Earth.

Read more: Global Air Pollution Has Fallen Due to the Coronavirus Outbreak, but Experts Warn It Isn’t a Silver Lining

One big variable is behavioral change. There, too, it behooves us not to make too much of the rapid changes that have just happened in the current COVID-19 crisis. Yes, some of those lucky enough to have stable salaried jobs have showed that it is possible to have somewhat productive work conversations from makeshift home offices, while homeschooling kids. Some might have even appreciated using COVID-19 as an excuse to avoid having a layover at O’Hare longer than that client meeting. Some of these changes might well be longer-lasting—and meaningful. After all, one cross-country round trip between New York and San Francisco emits about one ton of carbon dioxide per person. That single ton, in turn, melts around 3 square meters (32 square feet) of Arctic summer sea ice. Or the changes could easily backfire. This year’s regional sales meeting in Cleveland might have been one of the “COVID casualties.” Next year’s? Barcelona or bust.

Which way things might go is anyone’s guess. What’s clear is that government policy will play a large role. That policy ought to be guided by facts rather than fear, and it ought to ensure that the world steers clear from some of the all-too predictable worst-case climate scenarios—something many countries are so far failing to do with COVID-19. Like COVID-19, climate change, too, thrives on discounting expertise and dismantling basic social protections.

Addressing climate change isn’t easy. A return to fact-based policymaking, however, can at least make it possible. This pandemic ought to inspire a fundamental rethinking of the role of science and knowledge, the importance of competent leadership including global cooperation, and how the fate of the most vulnerable anywhere affects the fortunes of everyone everywhere. If it does, its true benefits to the climate will last well after the world gets back to work.

Gernot Wagner teaches climate economics at New York University, is a co-author of Climate Shock and writes the Risky Climate column for Bloomberg Green.

New story in Science and Health from Time: Global Air Pollution Has Fallen Due to the Coronavirus Outbreak, but Experts Warn It Isn’t a Silver Lining Global Air Pollution Has Fallen Due to the Coronavirus Outbreak, but Experts Warn It Isn’t a Silver Lining

Around the world an unexpected impact of the economic shuttering due to the coronavirus outbreak is striking blue skies and clear water in places, from Venice to Beijing, Los Angeles to Bangalore, where only weeks ago pollution dominated.

COVID-19 has driven the global economy to a near-halt as the pandemic sweeps the globe. With factories shuttered and cars parked in garages, air pollution has dissipated in cities. The Chinese capital Beijing, known for the lung-choking levels of toxic pollution that shroud the city, has had the unusual sight of clear skies as factories in the region have shut down production. Given China’s huge problems with air pollution, which causes an estimated 1 million premature deaths a year, the reduction has offered unexpected relief.

But environmental science and policy experts warn not to call this a silver lining; any sustainable reduction in emissions and pollution will need to happen in a way that doesn’t totally splinter society. And, moreover, they expect that pollution levels will return when the coronavirus ebbs—and in some cases may come back with a vengeance.

“I see it and I don’t think of a silver lining,” says Wade McGillis, an associate professor of earth and environmental engineering at Columbia University. “I see it and I think: those poor people who are not moving around and sheltered in place, and their lives being ruined.”

In the short term, the change is seemingly miraculous. Satellite images from the European Space Agency show reduced levels of nitrogen dioxide, a byproduct of burning fossil fuels that causes respiratory problems, across major cities on the continent including Paris, Madrid and Rome as countries lock down and restrict travel. Cities across the U.S. have seen similar effects as Americans stay home in traffic-prone cities like Los Angeles and New York.

In China, the world’s largest emitter of greenhouse gases, carbon dioxide emissions declined by a quarter in mid-February from a few weeks earlier, according to an analysis published in Carbon Brief. Scientists recorded similar declines in other pollutants like nitrogen dioxide and particulate matter in the country, which has spent years trying to clean the air in smog-choked cities. “In terms of a shift or a change that really happened overnight, this has been unprecedentedly dramatic,” says Lauri Myllyvirta, author of the Carbon Brief report and lead analyst at the Centre for Research on Energy and Clean Air.

In theory, this sharp decline in pollution and carbon emissions is a positive development for the planet and the humans who live on it. For one, air pollution contributes to millions of deaths across the globe every year, aggravating cardiovascular disease and respiratory health. Clearer air may also deliver some brief relief to those suffering from COVID-19, making it easier to breathe for patients who are struggling, though health experts say that years of exposure to pollution has likely made many people more susceptible to the disease. “The damage is already done,” said Sascha Marschang, acting secretary general of the European Public Health Alliance in a statement. “Years of breathing in dirty air from traffic fumes and other sources will have weakened the health of all those who are now embroiled in a life or death fight.”

The decline in emissions may also seem like a win for the fight against climate change. Climate scientists have warned that global carbon emissions need to peak in the coming years for the world to have even a remote chance of keeping temperatures from rising more than 1.5°C by the end of the century, a level that would likely bring a range of dramatic consequences from mass climate migration to the loss of the world’s coral reefs. As a coronavirus-related economic fallout, carbon emissions could decline in 2020. But, without a concerted effort, they’re unlikely to stay down.

The situation in China shows how quickly emissions and the related air pollution can bounce back. By the end of March, coal consumption and nitrogen dioxide pollution had returned to normal levels, according to Myllyvirta. A bigger long-term question remains: will the country use this moment to fund green stimulus measures to foster economic growth? Such a program could rapidly expand clean energy infrastructure and energy efficiency improvements even though robust support for green infrastructure will not sustain the dramatic decline in air pollution and emissions in the short-term—at least not yet.

Across the globe, policymakers will need to answer similar questions. If policymakers make a concentrated and sustained effort to decarbonize our economy, today’s clear skies give us a preview of what may come—even if it takes decades to get there.