TIME Innovation

Save the Planet With More Energy, Not Less

The Aspen Institute is an educational and policy studies organization based in Washington, D.C.

These are today's best ideas

1. What if to save the Earth, we need more energy and development, not less?

By Eric Holthaus in Slate

2. No big deal: Kids can now send their science experiments into space.

By Charley Locke in EdSurge

3. We basically know how to end — or at least stop the growth of — homelessness.

By Tim Henderson in Stateline

4. Soon, you could 3D-print your dinner.

By Heidi Ledford in Nature

5. Is this the technology that will finally give us flying cars?

By David Morris in Fortune

The Aspen Institute is an educational and policy studies organization based in Washington, D.C.

TIME Ideas hosts the world's leading voices, providing commentary and expertise on the most compelling events in news, society, and culture. We welcome outside contributions. To submit a piece, email ideas@time.com.

TIME Environment

How Earth Day Began: With Somber Reflection, and a Few Dump-Ins

Save Your Earth
Lambert / Getty Images An Earth day button, circa 1970

April 22, 1970: The first Earth Day is observed

Born from what TIME described in 1970 as a casual suggestion by Wisconsin Senator Gaylord Nelson, Earth Day was meant as neither protest nor celebration, but rather as “a day for serious discussion of environmental problems.”

What surprised Nelson — and others — was how much enthusiasm the idea engendered. On this day, April 22, 45 years ago, nearly 20 million Americans took Nelson up on his suggestion and turned out for the inaugural Earth Day events. These cropped up all over the country, on college campuses and in public places — including Central Park and New York’s Fifth Avenue, which was closed to traffic for two hours while 100,000 people staged a quiet, contemplative parade.

A dissonant combination of festivity and somber reflection pervaded the holiday. Environmentalists found themselves transformed into celebrities for a day, suddenly overrun with invitations to share their grim prognoses for the planet. As TIME wrote in 1970:

Ecologist Barry Commoner’s schedule was the busiest, calling for him to rush from Harvard and M.I.T. to Rhode Island College and finally to Brown University. Population Biologist Paul Ehrlich was lined up for speeches at Iowa State, Biologist René Dubos at U.C.L.A., Ralph Nader at State University of New York in Buffalo. In addition, such heroes of the young as Dr. Benjamin Spock, Poet Allen Ginsberg and various rock stars planned to have their say, if not precisely about ecology, then about the joys of the natural life.

Along with educational lectures and nature walks, however, there were livelier, more dramatic demonstrations meant to draw attention to the need for environmental reform. According to the New York Times, some activists held “mock funerals of ‘polluting’ objects, from automobiles to toilets.” Per TIME, students at several schools collected piles of litter and then staged “dump-ins” on the steps of city halls and manufacturing facilities.

At San Fernando State College, a group of students offered rice and tea to passersby as a sample of the “hunger diet” they could expect in the future, when overpopulation led to worldwide famine.

Meanwhile, at Florida Technological University, some students held a mock trial for a Chevrolet charged with poisoning the air. Finding it guilty, they set about executing it with a sledgehammer — but according to TIME, “the car resisted so sturdily that the students finally shrugged and offered it to an art class for a sculpture project.”

Despite — or perhaps because of — their heavy-handed theatrics, these grassroots protests paid off. By the end of the year, Congress had authorized the creation of the U.S. Environmental Protection Agency.

By the following year, Earth Day had grown into Earth Week, and this time it was officially sanctioned by President Nixon. But the festivities were “cooler and saner” the second year, per TIME, which noted, “Instead of noisy confrontations, the 1971 ‘week’ that ended April 25 ran to practical matters, like arranging bottle pickups.”

Read more about the importance of the environment in 1970, here in the TIME Vault: Issue of the Year

TIME Environment

Meet the Organizers of the Very First Earth Day

How a troupe of twenty-somethings mobilized millions of Americans to speak out on the environment

“It sounds as if the land has gone mad, and in a way some of it has—mad at man’s treatment of his environment.” When LIFE Magazine reported on the first Earth Day, which took place on April 22, 1970, it captured the burgeoning energy of a nascent environmental movement and the young men and women driving toward change.

The magazine’s focus was less on the pollution that threatened the planet than on the faces of the movement determined to curtail it. Senator Gaylord Nelson, a Democrat from Wisconsin, had conceived of an environmental campaign that employed tactics, like the teach-in, of the anti-war movement. But he needed a group of budding young activists to organize it from the ground up.

Nelson enlisted Harvard graduate student Denis Hayes as national coordinator. Hayes brought on classmates Andrew Garling, who would coordinate the Northeast, and Stephen Cotton, who would manage the media campaign. Arturo Sandoval, a Chicano activist, joined the team to manage the Western effort, along with Bryce Hamilton to organize high school students and Barbara Reid to coordinate the Midwest.

The paths they took to their cramped Washington, D.C., headquarters varied widely. Reid, who had worked on Robert Kennedy’s campaign and then for the Conservation Foundation, was the only one with solid credentials in the movement. Hayes, who would go on to be a pioneering influence in solar power, grew up in the forests and streams of southwest Washington but focused his prior activism on the Vietnam War, as did Garling. Cotton came up as a student journalist during the civil rights movement, and Sandoval had organized Chicano students and laborers to fight against discrimination.

From a dingy office above a Chinese restaurant, the team orchestrated a history-making event. When the day they’d been working toward finally came, 20 million Americans took to the streets to rally for a more earth-conscious society, and the modern environmental movement was born. As dire as the problems that faced the environment were, Hayes maintained an optimistic outlook. As he told LIFE, “There’s no survival potential in pessimism.”

Liz Ronk, who edited this gallery, is the Photo Editor for LIFE.com. Follow her on Twitter at @LizabethRonk.

Read next: This Is the App You Need to Download for Earth Day

Listen to the most important stories of the day.

TIME Internet

New Google Doodle Celebrates Earth Day 2015

Google The Earth Day 2015 Google Doodle.

It comes with a nifty little quiz

In 1970, 20 million Americans took to the streets to spread the message of environmental awareness, and in the process created the first ever Earth Day. To honor what has become a global observance, a new Google Doodle has been created for Earth Day 2015.

The brainchild of the late Wisconsin Senator Gaylord Nelson, Earth Day 1970 garnered bipartisan support and is widely considered to be the beginning of the environmental movement. The campaign led to remarkable change — generating momentum for the creation of the Environmental Protection Agency and the passing of the Clean Air Act, Clean Water Act and the Endangered Species Act.

In 1990 another big campaign was organized to honor the 20th anniversary of Earth Day and an estimated 200 million people worldwide participated in the celebrations. Afterward, President Bill Clinton awarded Senator Nelson the Presidential Medal of Freedom — the highest honor a U.S. civilian can receive.

Earth Day 2015 includes a cleanup of the Great Wall of China, beach-litter removal in Lebanon and an attempt to protect 25,000 acres of rain forest in Indonesia.

The doodle features a spinning globe with various animal animations inside the Google letters. With a click, the animation links to a fun quiz where people can find out “which animal are you?”

Read next: This Is the App You Need to Download for Earth Day

Listen to the most important stories of the day.

TIME Environment

New York Aims to Cut Waste by 90% by 2030

Trash
Bill Hornstein—Flickr/Getty Images

New York will announce an ambitious goal of reducing waste output by 90% by 2030

(NEW YORK) — The nation’s biggest city, in a far-reaching effort to limit its impact on the environment, is set to mark Earth Day by announcing the ambitious goal of reducing its waste output by 90 percent by 2030.

The Zero Waste plan, which includes an overhaul of the city’s recycling program, incentives to reduce waste and tacit support for the City Council’s plan to dramatically reduce the use of plastic shopping bags, will be announced by Democratic Mayor Bill de Blasio on Wednesday. Its goal is sweeping: New York would be the largest city in the Western Hemisphere to adopt the plan, which aims to reduce the amount of its waste by more than 3 million tons from its 2005 level of about 3.6 million tons.

The waste reduction plan is part of an update to the sustainability project named PlaNYC, created by de Blasio’s predecessor, Michael Bloomberg, to provide a framework for mitigating the impacts of population growth and a changing climate on the city’s infrastructure. De Blasio, who largely praised PlaNYC, is keeping its components but rebranding it OneNYC.

“The average New Yorker throws out nearly 15 pounds of waste a week, adding up to millions upon millions of tons a year,” de Blasio said in a statement to The Associated Press. “To be a truly sustainable city, we need to tackle this challenge head on.”

For decades, the city’s trash has been exported by rail or barge and sent to facilities in South Carolina, Virginia, New Jersey, Pennsylvania or upstate New York. The new plan would eliminate almost all of the garbage exports, which currently cost more than $350 million a year.

The amount of waste produced by the city has fallen 14 percent since 2005 due to an increase in recycling, and a key component of the Zero Waste plan is to bolster that output by simplifying the process.

Currently, residential buildings have two types of recycling bins. The city’s new single-stream plan, already used by other cities, would consolidate all of the recycling into one type of bin by 2020.

Organics — food scraps, yard waste and other things that cannot be recycled — make up 31 percent of the city’s residential waste stream. A program to collect that material directly from residents’ homes is being expanded to nearly 200,000 residents by year’s end, and officials want to serve every home in the city by the end of 2018. The city, which has about 8.5 million residents, also will offer economic incentives to participate, including potentially a property tax rebate for homeowners.

The city also aims to reduce commercial waste by 90 percent by 2030 by adopting a program similar to what is being used with residential buildings. That could also mean tax incentives for businesses who participate and fines for those who don’t.

And while the de Blasio administration stopped short of endorsing a City Council bill that proposes a 10-cent fee for use of plastic bags, officials said that reducing their use is a priority and that they would coordinate efforts with the council.

A spokeswoman for de Blasio said some of the funding for the Zero Waste program would be revealed in next month’s budget proposal but noted there would also be cost savings due to the dramatic reduction of garbage being shipped out of state.

The OneNYC presentation, which also is going to include other capital expenditures meant to improve the city’s aging infrastructure, is meant to build on de Blasio’s environmental record, which includes a ban on Styrofoam boxes and the goal to reduce carbon emissions from city buildings by 80 percent by 2050.

Environmental groups briefed on the plan Tuesday applauded its wide-ranging scope.

“We see cities all over the world struggling with waste,” said Michael Berkowitz, president of 100 Resilient Cities. “A more efficient city is a more resilient city, and that means it’s a stronger city.”

MONEY sustainability

10 Super Easy Practices That Are Good for the Earth—and Your Budget

In honor of Earth Day, here are 10 incredibly easy things we should all be doing: They're good for the environment and save money at the same time.

Taking major steps like installing rooftop solar panels or buying an electric car are hardly the only ways to go green. It’s very possible to practice an earth-friendly lifestyle without incurring a major cost outlay. In fact, tons of tiny, easy tweaks to what you do and what you buy day in, day out can not only help the environment, they’ll save you money as a bonus. Here are 10 green cost-saving practices for Earth Day—and every day.

  • Walk or Bike

    Capital Bikeshare, Washington, D.C.
    James A. Parcell—The Washington Post via Getty Images Capital Bikeshare, Washington, D.C.

    Cities and even many small towns are increasingly focused on becoming more walkable and bike-friendly. So why not take advantage? Obviously, neither of these modes of transportation requires the use of fossil fuels or electricity. They’re also free or nearly so. Depending on where you live, you might not even have to buy a bike: The bike share program in Washington, D.C., for instance, costs $75 per year and rides are free if they last 30 minutes or less. (Check out MONEY’s ranking of the Best Places to Walk or Bike.)

  • Group Errands Together

    150420_EM_EarthDay_GroupErrands
    Getty Images—Getty Images

    You could take separate car trips to go grocery shopping, get the oil changed in the car, and visit the doctor for an annual checkup. Or you could combine them into one outing, in a process some call “trip chaining,” which is as simple—or challenging, for some—as being a little more organized and efficient. By planning ahead and grouping errands, you save time and gas money and reduce congestion on the roads.

  • Use Public Transportation

    150420_EM_EarthDay_MassTransit
    Craig Warga—Bloomberg via Getty Images New York subway

    Some parts of the country have better public transit than others, and surveys indicate that people—millennials especially—place a high priority on living in cities with good options for getting around. This makes sense for a number of reasons. According to a study on commuter satisfaction, people who get to work on foot, bike, or via train are happiest. These options are not only more affordable compared with driving, the time of one’s commute is more consistent and therefore less stressful. Check out the tools at PublicTransportation.org to scope out transit options and see how much money and carbon emissions you could save by using public transportation in your neck of the woods.

  • Drink Tap Water

    150420_EM_EarthDay_WaterBottle2
    Alamy

    Americans spent roughly $13 billion on bottled water last year, up 6% from 2013. We’re drinking roughly 34 gallons of bottled water annually per capita, up from just 1.6 gallons in 1976. Granted, this is a much healthier option than sugary beverages, but is bottled water any better for us than tap water? According to the Environmental Protection Agency, tap water is completely safe; many bottled waters are just tap water that’s sometimes (but not always) filtered. And bottled water easily costs 100 times or perhaps even 1,000 times more than tap water. Only an estimated 23% of disposable plastic water bottles are recycled, by the way.

  • Shop with Reusable Bags

    canvas bag
    Getty Images

    The environmental benefits of shopping with a reusable bag like these recommended by Real Simple are pretty obvious: They eliminate the need for plastic bags that tend to wind up in landfills. Shopping with a reusable bag may also save you money, because stores in places like Dallas and Encinitas, Calif., charge customers 5¢ or 10¢ apiece for non-reusable bags.

  • Don’t Overdo It on Groceries

    shopping list
    Getty Images

    Somewhere between 25% and 40% of the food we buy in the U.S. is thrown away. What this shows is that too many of us buy too much at supermarkets and warehouse bulk-supply retailers, and/or that we’re not particularly good at strategically freezing or concocting leftover dishes. To waste less, shop smarter and be creative with foods that might otherwise be dumped in the trash. And to avoid going overboard with impulse purchases at the grocery store, always make a shopping list in advance, and stick to it.

  • Heat and Cool Your Home Wisely

    Insulation
    Jonathan Maddock—Getty Images

    Among the many straightforward and fairly simple steps you can take to trim back household costs and conserve resources: Turn the heat down in winter (you’ll shave 1% off your heating bill for every 1 degree lower); use fans rather than nonstop A/C in the summer; insulate around doors and windows to protect from drafts; and put heating and cooling systems on a timer so that they’re only in use when needed.

  • Use Energy-Efficient Lightbulbs, Appliances

    150420_EM_EarthDay_Lightbulb
    Alamy

    They tend to cost more upfront than less efficient models. But they’ll save you money in the long run because they eat up less electricity when being used, and, at least in terms of lightbulbs, they have longer lifespans so therefore have to be replaced less frequently. As for appliances, look for the Energy Star label as a sign of a product’s efficiency—and its potential to shave dollars off your utility bills.

  • Be Practical About Landscaping

    cactuses outside home
    Trinette Reed—Getty Images

    It’s not wise to battle against Mother Nature by trying to force flowers, plants, and grasses to grow in areas where they’re simply not suited. A low-cost, low-maintenance yard is one that incorporates native plants and greenery that flourish in your zone, without requiring extensive watering, fertilizer, and attention—nor a big budget. Check out classic tips from This Old House and Better Homes & Gardens for landscaping that’s gorgeous, affordable, and earth-friendly. Don’t fixate on having a prototypical grassy front lawn, which may look good but often requires loads of time, energy, money, water, and chemicals to maintain.

  • Compost

    Dumping compost
    Jill Ferry Photography—Getty Images

    Many towns give residents free or deeply subsidized composters, and using one is generally as simple as dumping vegetable peelings, coffee grounds, fallen leaves, grass clippings, and such into the bin. The resulting material can be help your garden and new plants grow, and eliminate much of the need to water and buy fertilizers and pesticides. Composting reduces the amount of waste in landfills as well, of course. (Even apartment dwellers can get in on the act with vermicomposting, or composting with worms.)

TIME apps

This Is the App You Need to Download for Earth Day

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Getty Images

It lets you keep a log of your daily energy consumption and tells you how to reduce it

Has commemorating Earth Day on April 22 got you in the mood to save some energy? There’s an app for that.

My Earth — Track Your Carbon Savings uses a simple diary format to help make you aware of the energy you’re using during your daily routine.

The app tracks your energy consumption in areas like electricity, travel and food, and within each category, there are suggestions for doing things differently to help conserve energy. Some of the suggestions are simple (like recycling) and some are complex (like installing a high-efficiency water closet). As you take up the suggestions, you accumulate carbon units and can quickly see how much energy you are saving.

A cute visual device — a polar bear perched on an iceberg — depicts your progress. The more energy you save, the bigger the iceberg gets.

Nancy Wong, the app’s designer and professor of consumer science at the University of Wisconsin at Madison, said on the institution’s website that in many people what looked like a lack of concern for the environment was really “a failure to connect individual action to that bigger picture.”

She explained that “Hopefully the app could help you understand actually whatever you do is not insignificant, and this is how you can contribute.”

TIME space

See If You Can Find Yourself in NASA’s #GlobalSelfie

It's probably the biggest selfie ever.

NASA created this giant selfie of Earth using selfies of individuals sent in from around the world. Can you spot yourself? It’s like the ultimate version of Where’s Waldo.

TIME Environment

Spending Earth Day at Ground Zero for Climate Change In America

We’ve all seen the iconic Blue Marble photo of the earth from space, the image that launched a thousand nature essays, but Bill Nelson and Piers Sellers are among the few people who have enjoyed that perspective on the planet in the flesh. Nelson is now a U.S. Senator from Florida, Sellers is a top NASA science official, and this morning, at an Earth Day hearing in my Miami Beach neighborhood, I got to hear the two former astronauts reminisce about the view from 10 million feet.

Senator Nelson recalled the color contrasts in the Amazon that illuminated the growth of deforestation. “The earth looked so beautiful, so alive—and yet so fragile,” he said. “It made me want to be a better steward of what the good Lord gave us—and yet we continue to mess it up.” Dr. Sellers remembered catching a glimpse of the Florida peninsula between his boots during a spacewalk. When you go around the world in ninety minutes, he said, you realize it’s a very small world.

“My take-home impression was that we inhabit a very beautiful but delicate planet,” said Sellers, a meteorologist who is NASA’s deputy director for science and exploration. “And the dynamic engine of planet Earth is the climate system that allows all life here to prosper and grow, including us humans.”

Now that climate is changing, and as Nelson said at the start of the South Florida hearing: “This is Ground Zero.” Scientists have documented that the seas along the Florida coastline have risen five to eight inches over the last fifty years, and Biscayne Bay now floods the streets of my neighborhood just about every month at high tide. “It’s real. It’s happening here,” Nelson said. “Yet some of my colleagues in the Senate continue to deny it.”

It is real, and it’s already a problem in my low-lying part of the world. Saltwater intrusion is increasing in the freshwater Everglades, which is causing problems for farmers in southern Miami-Dade County, and will make the government’s $15 billion Everglades restoration project even more expensive. The Army Corps of Engineers has estimated that over the next fifty years, Miami-Dade’s beaches will need about 23 million cubic yards of new sand to deal with erosion. Mayor Philip Levine says Miami Beach alone plans to spend $400 million to upgrade drainage infrastructure to prepare for a warmer world. The Intergovernment Panel on Climate Change’s “likely scenario” for 2010 includes seas rising as much as three feet; our county has $38 billion worth of property at three feet elevation or less. And while it’s too early to tie any particular storm to climate change, all the models predict more intense hurricanes coming through the Sunshine State. “The risk posed by coastal flooding is indisputably growing,” testified Megan Linkin, a natural hazards specialist at the reinsurance giant Swiss Re.

That’s incorrect. The risks posed by climate change, while real, are not at all indisputable. Lots of people, including most Republican politicians in Washington, still dispute them. As Senator Nelson said after the hearing, even Republican politicians in coastal areas—he cited Senator Lindsey Graham of South Carolina—rarely acknowledge the danger their constituents face from rising seas. “That would not be a popular topic in a Republican primary,” Nelson said.

But as Dr. Sellers pointed out, the IPCC believes the main cause of climate change is the burning of fossil fuels. And as Senator Nelson pointed out, it will take government action—he mentioned the possibility of a carbon tax—to reduce the burning of fossil fuels. “Otherwise, the planet will continue to heat up,” Nelson said.

Unfortunately, there is no chance of Congress passing a carbon tax anytime in the foreseeable future. President Obama couldn’t even get a cap-and-trade program through Congress when Democrats controlled both houses. Global warming has no juice as a political issue; people don’t think it really affects their lives.

That’s why Nelson held a hearing here at global warming’s Ground Zero, to try to show that global warming is already affecting lives. It was worth a shot, I guess. South Florida isn’t as threatened as those vanishing Pacific islands, but it’s basically America’s canary in the coal mine. Maybe my neighborhood’s outrage over the monthly lake in our Whole Foods parking lot will help spark a broader movement for change.

I doubt it, though. I get the political instinct to boil issues down to How It Can Affect You, but climate change is so urgent and invisible that if Congress has to wait for it to affect most Americans in tangible ways before taking action, Congress will be too late. Burning rivers and disappearing eagles helped build support for laws like the Clean Water Act and the Endangered Species Act; rising temperatures—all of the ten warmest years on record have occurred since 1998—and extreme events like Superstorm Sandy don’t seem to be having much of a political impact. President Obama has helped launch a clean energy revolution, and he will soon propose new regulations on carbon emissions, but the public has shown little interest in the issue.

Ultimately, the local argument against climate change—it might flood your neighborhood—seems a lot less compelling than the global argument, the Blue Marble argument. This is a nice earth. It’s our home. It’s the only planet with ice cream and the Everglades and the NBA playoffs. We should try not to mess it up.

“Spaceflight allows one to stand back, or float, and literally take in the big picture,” Dr. Sellers said in his testimony. It’s a perspective we sometimes overlook back here on Earth. Otherwise, we might decide to stop broiling it.

 

TIME Environment

The Earth Is Changing Rapidly. Can We Change Too?

Antarctica used to be warm
Moment/Getty Images

On Earth Day, we celebrate a planet that has nurtured human life. But it wasn't always so nice—and as the climate changes, it may get worse

I had the chance to see the Grand Canyon last week for the first time, and I can tell you this: it is really big. So big, in fact, that I led my partner on an endless walk along the rim, searching for the entrance a trail that would take us some of the way down the canyon. It turned out that I misread the map scale just a tiny bit. I think she may have forgiven me by now.

Of course, there’s more to the Grand Canyon than its sheer size: Its exposed rock reveals some 2 billion years of Earth’s geologic history, a span of time that is unfathomable by human beings (our species Homo sapiens is about 0.00005% as old as the oldest rock found in the Canyon). And even that time period covers less than half of the Earth’s age. Our planet is ancient, and the only constant over the course of its 4.54 billion-year history has been change—albeit change on a scale that almost always unfolds far too slow for us to realize it. If the Earth seems as solid as the ground beneath our feet, that’s only because we haven’t been around long enough to see just how unstable it really is.

That’s something to keep in mind as we celebrate the 45th Earth Day. Human civilization has flourished over the past ten thousand or so years largely because our species has been fortunate enough to arise during a Goldilocks (not too warm, not too cold) climatic period known as the Holocene. It’s an age that has proven ideal for agriculture and other activities that now support a human population of 7 billion-plus. But it hasn’t always been this way, as a new study that was published Monday in the Proceedings of the National Academy of Sciences demonstrates.

A team led by Yale University scientists used a new method to determine temperatures in the Earth’s past, measuring concentrations of rare isotopes in ancient fossil shells found in Antarctica. The researchers found that during the Eocene epoch—about 40 to 50 million years ago—temperatures in parts of Antarctica reached as high as 63 F (17 C), with an average of 14 C (57 F). That’s far above the mean annual temperature of Antarctica’s interior today, which registers at a frosty -70 F (-57 C), and closer to the kinds of temperatures you’d see in today’s San Francisco. Seawater around parts of Antarctica was even warmer, a balmy 72 F (22 C)—or about the same temperature as the tropical seas around Florida today.

If there were people living 40 million years ago—there weren’t, FYI—they could have been snorkeling off the coast of Antarctica’s Ross Island.

Why? Carbon dioxide levels in the atmosphere during the Eocene were much, much higher, perhaps as high as 2,000 ppm or more. Even though human beings have been pouring carbon into the atmosphere by the gigaton for decades, that’s still far higher than current levels, which stand at a little above 400 ppm. But even that increase has helped global temperatures rise by about 1.53 F (0.85 C) since 1880, and despite 45 Earth Days since the first in 1970, global carbon emissions just keep on growing, reaching a record 36 billion metric tons in 2013.

As Brad Plumer puts it over at Vox, our chances of keeping global temperature increase below 3.6 F (2 C)—a figure governments around the world have adopted as a climate change red line—seem vanishingly small:

If you look at the current rapid rise in global greenhouse-gas emissions, we’re on pace to blow past the 2°C limit by mid-century — and hit 4°C or more by the end. That’s well above anything once deemed “dangerous.” Getting back on track for 2°C would, at this point, entail the sort of drastic emissions cuts usually associated with economic calamities, like the collapse of the Soviet Union or the 2008 financial crisis. And we’d have to repeat those cuts for decades.

Needless to say, that’s unlikely. Barring some major political or technological revolution, our Earth will likely change more in the decades to come than it has for the entire lifespan of human civilization—and that change almost certainly won’t be for the better. As the PNAS study shows, the climate we think of as stable—the “long summer” of humanity—has been drastically different over the course of Earth’s deep past. The Earth will change. The question for the Earth Days to come is whether we can change, too.

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