The first Earth Day was revolutionary. That can be difficult to imagine today as we’re bombarded by calls for sustainability year-round. Yet only 46 years ago, some 20 million Americans protested and demanded that the government curb pollution, protect wildlife and conserve natural resources.

Remarkably, government leaders listened. In the years after the first Earth Day, the Environmental Protection Agency was founded. Congress passed the Clean Air Act, the Clean Water Act and the Endangered Species Act, among other powerful environmental laws. In short, Earth Day changed the trajectory of our country and, probably, the world.

Environmental scientists led the movement, predicting chilling futures—that overpopulation would cause worldwide famine; pollution would blanket cities and kill thousands; a mass extinction was upon us; oil and mineral reserves were about to run out. Nearly all of these predictions foresaw doom by the year 2000—which we’re now far past. While environmental concerns still reign, the extreme conditions predicted 46 years ago have, for the most part, not yet materialized.

It’s easy to poke fun at these “failed predictions”—and many environmental skeptics do. Those critics aren’t entirely wrong; some of the era’s predictions were based on faulty logic. But others failed to come true because the predictions themselves changed the course of history.

Running Out Of Everything

Many of the era’s incorrect predictions centered on resource scarcity—oil, minerals, food—but perhaps the most famous one came ten years after the first Earth Day, when a scientist and economist made a public bet that lives on in environmental discourse today.

The scientist was Paul Ehrlich, an outspoken biologist whose studies on the population dynamics of butterflies led him to a dramatic conclusion: That the human population was too big and soon would strip the world of resources, leading to mass starvation.

The economist was Julian Simon, who disagreed with Ehrlich. Humans are not butterflies, he argued, and have a powerful tool that prevents resource scarcity: a market economy. When a useful resource becomes rare, it becomes expensive, and that high price incentivizes exploration (to find more of that resource) or innovation (to create an alternative).

The two never met or debated in person. But in 1980, Simon challenged Ehrlich to a bet in the pages of a scientific journal, and Ehrlich accepted. The biologist selected five raw minerals—chromium, copper, nickel, tin, and tungsten—and noted how much of each he could buy for $200. If his prediction was right and resources were growing scarce, in 10 years the minerals should become more expensive; if Simon was correct, they should cost less. The loser would pay the difference.

In October 1990, ten years later, Simon received a check in the mail from Ehrlich for $576.07. Each of the five minerals had declined in price. Simon and his faith in the market were victorious.

“The market is ideally suited to address issues of scarcity,” says Paul Sabin, a Yale environmental historian who wrote the book on the Simon-Ehrlich Wager. “There’s often cycles of abundance and scarcity that are in dynamic relationship with each other where one produces the other.”

Take oil: Repeatedly over the past decades, oil prices have shot up, leading some people to predict peak oil—the end of fossil fuels and the start of an energy crisis. But by market logic, high prices encourage enterprising people to seek new oil sources, develop new extraction technologies, or otherwise invest in bringing oil onto the market. Demand and high prices brought us fracking, for instance, and now gas at the pump is cheaper than ever. Research into the next potential oil technology, extraction of methane hydrates, is already underway.

Similar patterns occur with minerals like copper, one of Ehrlich’s picks from his wager with Simon. At the time of the bet, the price of copper was on the rise, and, as a result, some investors took to copper production, increasing supply, says Sabin. Then in 1977, GE and Bell laid their first fiber-optic phone lines, which carry more information than copper wire. The new technology spread through the 1980s—and by the end of the Simon-Ehrlich wager, demand for copper was down, as was its price.

Each mineral from the bet has its own story, says Sabin, and many involve people. An international tin cartel collapsed, leading to a drop in tin prices. With other metals, strikes and union resistance were sorted out, and prices dropped.

Feeding the Planet

The biggest apocalyptic claims around the first Earth Day related to overpopulation and food shortages. "Population will inevitably and completely outstrip whatever small increases in food supplies we make," Ehrlich said in an often-quoted 1970 Mademoiselle interview. “The death rate will increase until at least 100-200 million people per year will be starving to death during the next ten years.”

Ehrlich was right about the growing population—but not about mass starvation. Famine and starvation continue throughout the world, but not to the extremes he predicted. The reason is the Green Revolution, which began decades before the first Earth Day, in Mexico, and really gained steam just about the time Ehrlich made his predictions.

In the 1940s, Mexico imported half of the grain needed to feed its population. Its government feared food scarcity and famine—and those fears sparked an agricultural revolution.

The Mexican Ministry of Agriculture teamed up with the Rockefeller Foundation to import American biologists to work on the problem, one of whom was Norman Borlaug. Over several decades, Borlaug used selective breeding to create strains of wheat with bigger kernels and smaller stems that could feed more people per acre; similar techniques were applied to rice. As a result, by 1980, wheat yields doubled in Pakistan and India, and poverty rates halved even as human populations expanded. By 1963, Mexico was exporting wheat instead of importing it.

Ultimately, Ehrlich and others’ predictions about feeding our growing population failed to come true; human ingenuity found a way. But even Borlaug acknowledged that increasing yields would not be a permanent solution.

“The green revolution has won a temporary success in man's war against hunger and deprivation; it has given man a breathing space,” Borlaug said in a speech after he received the Nobel Peace Prize in 1970. “But the frightening power of human reproduction must also be curbed; otherwise the success of the green revolution will be ephemeral only.”

The Pollution Problem

Around the first Earth Day, environmental scientists made dire predictions about pollution. “In a decade, urban dwellers will have to wear gas masks to survive air pollution,” reported Life magazine in 1970. “At the present rate of nitrogen buildup, it’s only a matter of time before light will be filtered out of the atmosphere and none of our land will be usable,” said ecologist Kenneth Watt.

These predictions didn’t come to pass, but not because of economic incentives. When the synthetic pesticide DDT caused bird populations to plummet, as Rachel Carson documented in Silent Spring, there were no market incentives to reverse that trend. An increase in lead poisoning or asthma creates a market for medicines and treatment, but not for decreasing the pollutants that cause them.

And so on that first Earth Day, people fighting oil spills, power plant pollution, pesticides and litter protested in the streets. The government responded to public outcry, activism and the collective predictions of the era by creating our most powerful environmental laws—the Clean Air Act, the Clean Water Act, the Endangered Species Act and others.

“The sense of concern, the feeling of crisis, the agitation and political mobilization associated with [the era’s predictions] interestingly had an effect not on energy or mineral resource production but on control of pollution,” says Sabin. “People like Ehrlich shared a vision that the path that we were on wasn’t a good one, that it was headed towards crisis—and that gave energy and support for the legislation.”

And the regulations have worked. After DDT was banned in 1972, populations of bald eagles and other birds rebounded. Regulations on nitrogen dioxide and particulate pollution have improved air quality in cities alongside children’s lung development. In the late 1970s, 88 percent of American children had elevated lead levels in their blood; after leaded gasoline was phased out, that number dropped to less than 1 percent.

Pollutants continue to cause problems; the horrific case of lead poisoning in Flint show that regulations are not perfect solutions. But those predictions and the resulting activism during the first Earth Day drove change.

The Legacy Lives On

Even though the dire predictions didn’t come to be, they live on in our environmental discourse—and then as now, the most extreme voices get the most attention.

“It is important to acknowledge that there’s a relationship between the past predictions and the current ones,” says Sabin. “They helped feed a dynamic of extremes with both sides bashing each other.”

This is evident in the loudest parts of the climate change discussion. Extremists on one side are certain the world is going to end; extremists on the other are certain everything is fine and climate change is a conspiracy.

The truth is more complicated. Climate change won’t destroy the planet, although it will change the environment we’re accustomed to, in ways we can't predict and with possibly dire consequences. And weaponizing “failed predictions” of the past to justify leaving the climate problem to the market is deceptive. If we don't act because a previous prediction "failed," we face an array of human suffering, which will hit the poorest and disadvantaged the hardest.

“We should try to figure out the relationship between the earlier predictions and the current ones,” says Sabin, “The environmental community and advocates for climate action will be in a stronger position if they can figure out how to explain why climate change is different [from past predictions of resource scarcity] and why we need to take action now.”