New story in Science and Health from Time: I Found a Rainbow At the End of My Hunt For a Vaccine Appointment I Found a Rainbow At the End of My Hunt For a Vaccine Appointment

A version of this article also appeared in the It’s Not Just You newsletter. Sign up here to receive a new edition every Sunday.

CHASING RAINBOWS (AND VACCINES)

We humans are notoriously unreliable, superstitious narrators, always scanning the horizon for signs that validate what our hearts have already told us. Take me, for example. I keep telling people I was vaccinated at Hogwarts’ Manhattan campus under the waxing moon (it was a gibbous moon to be exact). How auspicious!

Ok, so my COVID-vax site was really The City College of New York. But stepping through its big old gothic gates to receive a blessing of science was wondrous, maybe a little spiritual. There was even a rainbow-y halo around that big moon, another lucky omen if you’re hungry for such things.

I started digging for lore on moons and rainbows and learned that the physics of rainbows doesn’t detract from the mythical place they have in our cultural imaginations. In fact the opposite.

Just ask Steven Businger, professor and chair of Atmospheric Sciences Department at University of Hawai’i in Manoa. He’s a co-creator of RainbowChase, an app that alerts users when nearby conditions are conducive to rainbow sightings. And after decades in a state where mind-blowing rainbows are a daily occurrence, Businger still pulls over to take photos of them. “I’m completely spiritually gobsmacked by rainbows,” he says.

Photograph courtesy of Steven Businger/University of Hawai’i in ManoaHawaiian rainbow, or Ānuenue

Most of Businger’s research has to do with hazardous weather, storm evolution, and forecasting. But in this pandemic year, he went on a bit of a glorious tangent to look at the science and mythology behind Hawaii’s prolific rainbows, which he posits are the most spectacular on Earth thanks to the state’s unique geography and weather patterns.

“The Hawaiians thought the rainbow was a path to a higher dimension, and in a real sense, it is,” says Businger.

<strong>The rainbow plays with our consciousness, and it’s a beautiful interplay. You look at it, you meditate, and boom, you’re in touch with a higher dimension</strong>.

The idea of the rainbow as a source of life, or a bridge to another plane, is embedded in cultural traditions across the world, from the ancient Greek rainbow goddess Iris to Aboriginal people of the desert’s stories of the Rainbow Serpent and the mythical Norse rainbow bridge to the land of the gods, Bifrost.

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In Businger’s March 11 article, “The Secrets of the Best Rainbows on Earth,” he points out that there are more than a dozen different words for rainbow in Hawaiian. There are Earth-clinging rainbows (uakoko), standing rainbow shafts (kāhili), and barely visible rainbows (punakea).

There is also something called a moonbow, or lunar rainbow, a rare event in which the moon refracts light through water droplets in the air creating a kind of rainbow, similar to what the sun does.

And alas, Businger tells me that the colors I saw in the halo around the moon at City College were a moonbow which, like a rainbow, is only seen when the moon or sun is behind you.

What I likely saw on my way to get my coronavirus vaccine was a gorgeous lunar corona. And with that, I rest my mystical case.

Photograph courtesy of Steven Businger/University of Hawai’i in ManoaA vertical rainbow, or Kāhili over Hawaii

Unfolded by rainbows are the faces of the flowers.

–Hawaiian proverb

Check out Steven Businger’s interview on Science Friday for more rainbow science.

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And write to me at: Susanna@time.com

COPING KIT ⛱

<strong>The sun’s white winds blow through you, there’s nothing above you, you see the earth now as an oval jewel, radiant & seablue with love.</strong>you don’t have to be everything Poems for Girls Becoming Themselves is a gift-worthy collection of 68 poems organized by emotion including works by Amanda Gorman, Sharon Olds, and Margaret Atwood.

―Margaret Atwood, Flying Inside Your Own Body

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<strong>Empathy is a superpower, most especially in the workplace. It builds connection, makes for less dysfunction, and helps you find your way to the right purpose</strong>.EMPATHY FOR CHANGE is a new guide to cultivating empathy in thought and action, and why it’s an essential 21st-century skill. Author and former White House entrepreneur-in-residence Amy J. Wilson writes:

EVIDENCE OF HUMAN KINDNESS❤️

Here’s your weekly reminder that creating a community of generosity elevates us all.

The Antidote to Pandemic Loneliness

<strong>These strangers saved my life.</strong> </span><strong><span data-preserver-spaces="true">In a few weeks, I received thousands of emails and had regular pen pals…people who told me that I mattered and filled my heart with hope and joy. I no longer felt so alone. I realized that everyone feels the way that I did at some point</span></strong>.<span data-preserver-spaces="true">  

Denise, a 37-year-old woman from Phoenix, wrote Pandemic of Love last May that being quarantined made her realize how alone she was. She began to wonder if anyone would even notice if she disappeared. POL Founder Shelly Tygielski called her to check-in. Then Tygielski asked her Instagram followers to “FLOOD a special email address with letters for Denise telling her she matters, that she is important, beautiful, and SEEN.” Denise has since received more than 3,000 emails via lovelettersfordenise@gmail.com. She writes:

Story and images courtesy of Shelly Tygielski, founder of Pandemic of Love, a grassroots organization that matches volunteers, donors, and those in need.

COMFORT CREATURES 🐕 🐈

Our weekly acknowledgment of the animals that help us make it through the storm.

Meet PEACHES submitted by MARY, who didn’t intend to get a puppy, but now isn’t sure she would have made it through these surreal times without her.

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Send comfort creature photos and comments to: Susanna@time.com

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New story in Science and Health from Time: Digital NFT Art Is Booming—But at What Cost? Digital NFT Art Is Booming—But at What Cost?

In central Washington State, electric utilities are watching for homes with oddly high power usage after a recent surge in cryptocurrency prices collided with a boom in NFTs, or “non-fungible tokens”—an emerging technology that uses crypto platforms to authenticate ownership of digital files. In an emerging hype cycle, such digital assets have sold at auction for millions of dollars, giving the buyer claim to an “original” version of a computer file, such as a piece of digital art or a sports highlight video.

During the last crypto boom, the region—home to some of the cheapest electricity in the U.S.—was beset by a new energy-hungry home industry: basements and sheds loaded with racks of computers churning through advanced mathematical calculations in order to “mine” valuable crypto coins like Bitcoin or Ethereum. Even those small mining operations can overload local grids, creating a problem for local utilities. Around the world, vastly larger cryptocurrency operations have sprung up from Texas to Iran to China’s Inner Mongolia—almost anywhere miners can hook up to cheap electricity—filling air-conditioned, warehouse-sized spaces with endless rows of high powered computers running software to essentially convert energy into wealth.

While NFTs hold promise, critics say the mining that makes them possible is perhaps humanity’s most direct way of making money by polluting the planet–­Ethereum mining consumes about 26.5 terawatt-­hours of electricity a year, nearly as much as the entire country of Ireland and its almost 5 million residents. In theory, all mining energy could come from renewable sources, but right now, there is money to be made by essentially converting cheap fossil fuels into valuable cryptocurrencies. And for an asset with no physical presence or utility outside the digital realm, the process of producing the “coins” is tremendously inefficient–one 2018 study found that cryptocurrency mining consumes more energy for every dollar of value generated than extracting gold or copper.

“This is just heartbreaking in so many aspects,” says Camilo Mora, a professor of geography and environment at the University of Hawaii, Manoa. “Not only the environmental [toll], but the social and ethical.”

All this may come as a surprise to artists and others adopting NFTs, in part because they’re far removed from the technology’s environmental cost. If a digital artist wants to sell an NFT, they first have to “tokenize” their work on a blockchain, which is a kind of tamper-resistant digital public ledger; many use the Ethereum blockchain. To do that, they pay Ethereum miners a fee of up to a few hundred dollars to have their computers crank out the necessary calculations. But from the artist’s perspective, they’re just paying money on a website to get a token in return, masking the environmental cost. “If you are buying an artwork you don’t see those calculations going on,” says Alex de Vries, a financial economist and founder of Digiconomist, a site that explores the unforeseen consequences of technology trends. “You don’t see your money is going to a miner who’s going to pay for fossil fuel-based energy with it. That’s a real problem.”

This issue–an “externality,” in economist-speak–extends far beyond the digital art world. It’s long been a problem for Bitcoin, the largest and most mainstream cryptocurrency, and it only stands to become a bigger dilemma as other kinds of assets, like financial securities and real estate, also become tokenized. Some in the crypto world are working on solutions. The developers of Ethereum itself, for instance, promise to launch a new framework that would use orders of magnitude less energy than the current system by 2022. But cryptocurrencies like Ethereum have taken off in part because they’re decentralized, which attracts techno-libertarians and others intrigued by the idea of currencies and assets unmoored from a government or central bank. That decentralization means there’s no single leader or body that could force everyone using Ethereum to shift to a new, more efficient system. “It’s pretty much guaranteed that miners will continue to run Ethereum in its current form,” says de Vries, pointing to the millions of dollars that Ethereum miners have already poured into their setups.

For now, this year’s NFT craze appears destined to not only fuel coal-hungry server farms from the Texas plains to the Caucasus, but also to power a new wave of hype around cryptocurrencies more broadly, incentivizing the creation of yet more massive and wasteful mining operations. Still, the recent boom is raising fresh awareness of crypto’s environmental toll, and there’s a chance that activism could lead to real change–but many are skeptical that enough will be done in time. “This was a game,” says Mora. “It’s turning into a disaster.”

New story in Science and Health from Time: Listen to the Sounds of NASA’s Perseverance Rover Driving on Mars Listen to the Sounds of NASA’s Perseverance Rover Driving on Mars

You wouldn’t think sound could travel very well on Mars—what with the planet’s bare wisp of an atmosphere, which is just 1% the thickness of ours. Yet if you could stand without a spacesuit on the Martian surface (not advised) you’d actually hear plenty. That fact has already been confirmed by the Perseverance rover, which landed on Mars on Feb. 18 and, using a microphone attached to a mast that holds a camera, has picked up sounds of the stirring of the wind and the ticking of its on-board laser as engineers test-fired it. (The laser is used to vaporize bits of rock which the rover can then analyze with its spectrometer.)

Now, NASA has used a second microphone to record a much more evocative sound: the turning of wheels and the crunching of gravel as Perseverance rolled its first 27 m (90 ft) on the surface of the Red Planet. The rover moves slowly—so slowly that the little trip took 16 minutes, which makes for fascinating if admittedly labored listening. But NASA also released a cleaned up, 90-second version which filtered out a persistent squeaking sound—one that engineers think could be caused either by the movement of the wheels or electronic interference with some of the rover’s instruments.

NASA · Sounds of Perseverance Mars Rover Driving – Sol 16 (16 minutes)

“If I heard these sounds driving my car, I’d pull over and call for a tow,” said Dave Gruel, a lead engineer, in a statement that accompanied the release.

The Martian sound effects come courtesy not of a purpose-built, extra-special interplanetary microphone, but from a simple, off the shelf model that was originally included to capture the sounds of the spacecraft’s descent and landing, but continues to function. In the event anybody in the rover’s vicinity calls out a hello, the mic will surely capture that, too.

New story in Science and Health from Time: How Industrial Fishing Creates More CO2 Emissions Than Air Travel How Industrial Fishing Creates More CO2 Emissions Than Air Travel

It’s been well established by now that the agricultural systems producing our food contribute at least one fifth of global anthropogenic carbon emissions—and up to a third if waste and transportation are factored in. A troubling new report points to a previously overlooked source: an industrial fishing process practiced by dozens of countries around the world, including the United States, China, and the E.U.

The study, published today in the scientific journal Nature, is the first to calculate the carbon cost of bottom trawling, in which fishing fleets drag immense weighted nets along the ocean floor, scraping up fish, shellfish and crustaceans along with significant portions of their habitats.

According to calculations conducted by the report’s 26 authors, bottom trawling is responsible for one gigaton of carbon emissions a year—a higher annual total than (pre-pandemic) aviation emissions. Not only does the practice contribute to climate change, it is extremely damaging to ocean biodiversity—the “equivalent of ploughing an old-growth forest into the ground, over and over and over again until there is nothing left” according to lead author Enric Sala, a marine biologist who is also National Geographic’s Explorer in Residence.

Bottom trawling is also one of the least cost effective methods of fishing. Most locations have been trawled so many times, there is little left worth catching, says Sala. “Without government subsidies, no one would be making a penny.” But Sala didn’t set out to condemn bottom trawlers when he designed the research project back in 2018. He was looking for the incentives that just might make the fishing industry, and governments, give up on the practice on their own. The carbon findings may just do the trick.

Read more: Why This Year Is Our Last, Best Chance for Saving the Oceans

The study, which breaks the entire ocean down into 50-km-square units, measures how much each so-called “pixel” contributes to global marine biodiversity, fish stocks and climate protection, based on a complex analysis of location, water temperature, salinity and species distribution, among other factors. It also tracks how much CO2 each pixel is capable of absorbing as a carbon sink. (Overall, the ocean absorbs about a quarter of global CO2 emissions a year, though the amount fluctuates between regions).

By mapping those pixel-level baselines the study can then calculate the impact of increasing or decreasing fishing and other human activities. The overall goal was to develop a map of ocean locations that, if protected, would produce the maximum benefits for humans in terms of increased fish stocks, biodiversity and carbon absorption while minimizing a loss of income for the fishing industry. “The reason why we only have seven percent of the ocean under protection is because of the conflict with the fishing industry,” says Sala.

Refuting a long-held view that ocean protection harms fisheries, the study found that well placed marine protected areas (MPAs) that ban fishing would actually boost the production of marine life by functioning as fish nurseries and biodiversity generators capable of seeding stocks elsewhere. According to the study results, protecting the right places could increase the global seafood catch by over 8 million metric tons a year, despite the challenges of overfishing and climate change.

Bottom trawling, however, would have to stop, says Sala. While mangroves, kelp forests and sea grass meadows are good at capturing carbon, the bottom of the ocean, piled deep with marine animal debris, is a far greater carbon sink. But when the trawlers’ weighted nets scrape the sea floor that carbon is released back into the water. Excess carbon in water turns it acidic, which is damaging to sea life.

Worse still, the practice also impacts the ocean’s ability to absorb atmospheric carbon: if the water is already saturated from sources down below, it will be unable to absorb human-caused emissions from above, hamstringing one of our best assets in the fight against climate change. By combining publicly-available data on global bottom trawler activity with pixel-level assessments of carbon stored in the top layers of ocean sediments, Sala and his team were able to calculate the amount of emissions produced by the technique, down to the level of national fleets. The European Union, for example, releases 274,718,086 metric tons of marine sediment carbon into the ocean a year, while Chinese fleets release 769,294,185 metric tons, and the United States releases 19,373,438.

If, as a 2018 study on the economics of fishing the high seas points out, bottom trawling is the least profitable method of harvesting the ocean’s bounty while producing the most carbon, it makes little sense for industry to continue, says Sala. Now, armed with the science along with the math, countries could conceivably put a halt to bottom trawling while selling the offsets to pay for marine protection.

Technological innovations such as green power generation and battery storage are vital for reducing global greenhouse gas emissions. But we still need to reduce atmospheric carbon, and so far technology has not been able to do that affordably and at scale. The oceans have been absorbing carbon for millennia, says Sala. The best way to reduce global emissions is to allow them to keep doing their jobs. “Most people still see the ocean as a victim of climate change. What people don’t realize is that nature is half of the solution to the climate crisis.”

New story in Science and Health from Time: Mars Has Much More Water Than Previously Known—But There’s a Catch Mars Has Much More Water Than Previously Known—But There’s a Catch

There’s never been much mystery surrounding the murder of Mars. Once a warm, wet world, Mars lost its magnetic field more than 4 billion years ago when its outer core cooled, shutting off the dynamo that kept the field in place. That exposed the planet to the solar wind, which clawed away at the atmosphere; and that in turn allowed the planet’s water to sputter off into space. To look at Mars today is to see a desert world, stamped with the dry riverbeds, delicate deltas and deep ocean basins hinting at the water that is no more.

At least, that’s the long-accepted view. But according to a study published Mar. 16 in Science by a team of researchers at the California Institute of Technology, that scenario might be all wrong. Mars is dry, alright—or at least it appears to be. But the researchers say much of its water—from 30% to a staggering 99% of it—is still there. It simply retreated into the martian rocks and clay rather than escaping into space.

Just how much water once flowed across the surface of Mars is expressed by a unit of measure known as “global equivalent layer” (GEL)—the depth that the water would be if it were not sequestered in basins and rivers, but instead were spread evenly across the entire planet. The best estimates for Mars’s original GEL is anywhere from 100 to 1,500 meters (330 to 4,900 ft). That’s an awfully wide range, but today it’s considerably narrower: the modern-day water on the planet’s surface—almost entirely trapped in its polar ice caps—has a GEL of just 20 to 40 m.

When Mars lost its atmosphere, all that original water had to go somewhere. The evaporation-to-space route was always the easiest explanation—but it’s a flawed one, too. The problem, as the Caltech researchers knew, involves hydrogen. As Martian water molecules rise into and then escape from the atmosphere, they disassociate into free hydrogen and oxygen atoms. An oxygen atom in water is just an oxygen atom, but hydrogen comes in two forms: ordinary hydrogen (with a single proton in its nucleus) and deuterium (with a proton and a neutron). Water molecules made of heavier deuterium instead of ordinary hydrogen are known, straightforwardly enough, as heavy water.

“The vast majority of hydrogen in the universe is just hydrogen,” says Bethany Ehlmann, professor of planetary science at Caltech and a co-author of the paper. “But there’s that tiny fraction that is deuterium. In the Earth’s ocean it’s almost one [heavy water molecule] in a million.”

The greater weight of deuterium causes it to behave differently in the Martian atmosphere. While free hydrogen atoms that were once part of a water molecule escape into space, free deuterium weighs enough to hang around in the air. Over time, as more and more hydrogen drifts away from the planet and more and more deuterium stays behind, the ratio of deuterium to hydrogen (D/H) slowly grows.

“The loss of hydrogen is a sort of constant removal,” says Eva Lingh Scheller, Caltech PhD candidate and the lead author of the paper. “Removing it from the total volume is going to give you a larger D/H ratio.”

But there’s a problem with common measures of Mars’s D/H ratio, Scheller and her colleagues found. Using atmospheric observations by NASA’s MAVEN Mars satellite and the European Space Agency’s Mars Express craft, they concluded that the current ratio is simply too low. If all of Mars’s water had escaped to space, taking its free hydrogen atoms with it, there would be much more deuterium in the modern day Martian sky relative to the remaining free hydrogen—by some measures, more than twice as much. That means that much of the planet’s water never escaped, and the only other place it could have gone was into the soil and rocks—especially into clay, the most abundant mineral on Mars.

“If you suck the water out a different way and let the remainder escape to space, that solves the [D/H] conundrum,” says Ehlmann.

The 30% to 99% range that the researchers posit for the amount of Martian water stored in the ground is admittedly imprecise—and will likely narrow definitively only when humans can collect fresh samples and study them up close. Either way, the fact that the planet may be so heavily hydrated does not, alas, mean much for the possibility of Martian life, since the water molecules are entrained in the rocks and clay, not percolating in free-standing underground pools. Humans explorers, on the other hand, could make use of the hydrated clay—a little.

“You heat your rock to 300º or 400º C and then it would release its water,” says Scheller. “But there’s only a little there so you’d have to cook up a lot of rocks to get any appreciable water.”

Adds Ehlmann: “Water ice is still your best bet.”

Whatever use humans may or may not make of Martian water, the planet clearly has plenty of the stuff. A world we have come to see as entirely barren, is now, we know, at least a little less so.

New story in Science and Health from Time: U.N. Study Finds Just 2.5% of Pandemic Response Funds Committed So Far Will Help Fix the Climate and Environment U.N. Study Finds Just 2.5% of Pandemic Response Funds Committed So Far Will Help Fix the Climate and Environment

In 2020, the colliding crises of the COVID-19 pandemic and increasingly visible climate change led many governments, politicians and campaigners to adopt the slogan “build back better,” promising to use economic recovery funds to accelerate the transition away from fossil fuels and create societies that are more resilient to extreme weather and other climate-related shocks.

But that hasn’t happened yet. A study published March 10 by the U.N. Environment Program, in partnership with the University of Oxford, found that of the $14.6 trillion committed by governments of the world’s 50 largest economies in 2020, just 2.5% was on programs likely to decrease greenhouse-gas emissions, lower pollution or restoring degraded natural systems.

The figures do not include the $2 trillion in climate spending promised by U.S. President Joe Biden, the details of which are still being hammered out. Nor does it include the European Commission funds of those E.U. member states that have not yet announced how they will allocate their budgets. Those un-declared funds are worth more than $2 trillion, according to the report, and with the E.U. leaders driving the green recovery agenda, they are likely to increase the proportion of global recovery spending that is directed towards reducing emissions.

Still, the report “clearly shows that we are not yet building back better when it comes to recovery spending,” writes UNEP executive director Inger Andersen. “On the whole, so far global green spending does not match the severity of the three planetary crises of climate change, nature loss, and pollution, leaving significant social and long-term economic benefits off the table.”

Of the total amount analyzed in the UNEP report, $1.9 trillion was classified as “long term recovery” spending; green recovery initiatives made up 18% of that. Brian O’Callaghan, head of the Oxford University Economic Recovery Project, said much of the remaining 82% represented missed opportunities for governments to speed up the fight against climate change. “Governments in many cases are just trying to return to the old normal,” he told a launch event for the report. “It seems like the world is trying to put out a house fire with a garden hose when a perfectly good fire hydrant is available just next door.”

Green investment commitments in 2020 were not equally distributed among countries, with most of it driven by “a small set of high-income nations.” Based on proportion of GDP, Spain, South Korea, and the U.K. led on green spending during the pandemic—though that is partly because these countries have announced the allocations of greater shares of their recovery plans than most countries so far. But when considering green spending as a proportion of recovery funds so far announced, Denmark, Finland, Germany, France, Norway, and Poland led.

The analysis doesn’t mean there will be no further pandemic-related green spending. The report argues that the window for green recovery investment is “only now opening” and urges governments to prioritize five areas for investment in 2021: green energy, green transport, green building upgrades & energy efficiency, green research and development, and restoring and protecting natural eco-systems and the services they provide.

“Trillions in fiscal spending [still to be announced] provide the greatest opportunity in decades to reorient for the future,” it reads. “Citizens, businesses, policy makers, and politicians must hold each other to account to ensure that the opportunity is not wasted.”

New story in Science and Health from Time: The COVID-19 Pandemic’s Impact on Global CO2 Emissions Didn’t Last Very Long The COVID-19 Pandemic’s Impact on Global CO2 Emissions Didn’t Last Very Long

It’s awfully hard to find any upside in a global pandemic that’s sickened nearly 115 million people and killed more than 2.5 million. But throughout 2020, there was some good news buried in the bad concerning that other great infirmity: the sickly state of the earthly climate. When economies are booming and people are moving, greenhouse gasses soar. It follows then that economic slowdowns and global lockdowns would lead energy use and greenhouses gas emissions to plummet—and they did. At least, at first.

According to a report released March 2 by the International Energy Agency, 2020 on the whole saw a total drop-off in global CO2 emissions of 6%—the largest annual decline since World War II—keeping almost 2 billion tons of planet-warming gasses out of the sky. That’s about the same as eliminating the entirety of the European Union’s annual CO2 output.

The bad news is that as the global economy begins to stir—thanks in part to the uneven if undeniable success of lockdowns, social distancing and the availability of vaccines—emissions are on the rise again. In December of 2020, not only had CO2 output rebounded, it actually rose to a level 2% higher than in the same month in 2019. “The rebound in global carbon emissions toward the end of last year is a stark warning that not enough is being done to accelerate clean energy transitions worldwide,” said Fatih Birol, executive director of the IEA, in a statement that accompanied the release of the study. “If governments don’t move quickly with the right energy policies, this could put at risk the world’s historic opportunity to make 2019 the definitive peak in global emissions.”

The overall arc of emissions in 2020 closely mirrored the severity of the pandemic. The global nadir came in April, when worldwide CO2 emissions were roughly 14% lower than they were in April of 2019—just at the point at which most countries were retreating into their first and strictest wave of lockdowns.

Different sources of CO2 were affected in different ways throughout the year. Aviation was down by a staggering 70% during the April low. Overall, emissions from the sector fell by 45% in 2020, the equivalent of taking 100 million cars off the road. Car, bus and motorcycle transportation accounted for 50% of the year’s total drop in CO2 emissions. Demand for oil fell by 8.6% in 2020. Demand for coal was down by 4%.

Geography mattered, too. China, the world’s largest emitter of greenhouse gasses and the first country hit by the pandemic, went into lockdown in February, resulting in its CO2 output falling by 12% compared to the same month a year prior. The country’s swift action and strict quarantine rules allowed it to begin returning to something closer to normal by April, when CO2 emissions in the country rose above 2019 levels. China finished 2020 with overall CO2 output 5% higher than it was in 2019.

India, with its 1.4 billion people, saw its emissions fall by a dizzying 40% in April, the largest decline of any major economy. The slowdown in industrial and freight output kept an estimated 50 million tons of CO2 out of the air, with major Indian cities experiencing clearer skies than they have seen in years. But the good environmental times didn’t last and in September, CO2 output returned to 2019 levels. Brazil similarly saw its output fall by more than 20% in April and was similarly back above 2019 levels by the end of the year.

In general, emerging economies were less likely to reduce their CO2 output, with emissions falling by only 4% there in 2020 compared to 10% in developed economies. The main cause for that difference was the rebound in road transportation in the emerging world in the second half of 2020.

In the U.S., the scattershot, state-by-state lockdown rules meant less dramatic fluctuations in output, with year-over-year emissions drops never reaching 20%, and a 10% reduction overall for 2020. And there, too, emissions approached 2019 levels by December.

One thing the pandemic didn’t seem to affect was the ongoing increase in the share of energy coming from renewable sources. In 2020, renewables accounted for 29% of all energy generated, compared to 27% in 2019—the largest year-over-year increase on record. But the upward drift of fossil fuel use at the end of the year nonetheless discourages experts.

“In March 2020, the IEA urged governments to put clean energy at the heart of their economic stimulus plans to ensure a sustainable recovery,” said Birol. “But our numbers show we are returning to carbon-intensive business-as-usual.”