Organizer of the First Earth Day
When Denis Hayes climbed onto the speaker’s platform in Manhattan in April 1970, the crowd on 5th Avenue stretched as far as he could see. The first Earth Day had struck a nerve, drawing 20 million participants nationwide.
A few months earlier he’d been a 24-year-old student at Harvard’s Kennedy School, invited to a 15-minute courtesy meeting with Senator Gaylord Nelson of Wisconsin to discuss organizing Earth Day in Boston. Days later, Nelson’s office called back and asked if he’d drop out of school to organize it nationally. He packed up for D.C. within the week. The rest is history.
But when I spoke with Denis in June 2026, I wasn’t primarily interested in Earth Day. I wanted to understand what had sustained his commitment to the environment for more than half a century. What had fueled that lifelong sense of mission?
The answer led back to a lonely childhood, an existential crisis in college, and a sleepless night in the Namibian desert that changed the course of his life.
It Started with Trees
Denis’ journey started with trees, which was both a gift and a grief.
His family moved from Canada to Camas, Washington when he was six. As a socially isolated child, he spent much of his time alone in the woods. “I really developed a kinship with trees,” he said. “I literally talked to trees because I didn’t have anybody else to talk to.” Looking back, he believes those solitary hours shaped his lifelong relationship with the natural world.
But Camas was also a mill town that “processed” trees, and Denis witnessed severe industrial pollution firsthand: sulfur dioxide and hydrogen sulfide emissions that fell as acid rain, toxic discharge into the river, fish kills, and clear-cut logging. “I woke up with a sore throat every morning for the first 17 years of my life,” he recalled. “I thought there must be a better way to harvest wood and make paper.”
His father worked at the mill and identified strongly with the industry that sustained the town. Denis largely rebelled against that worldview, and his environmental work became, in part, a reaction to the destruction he saw growing up.
That “better way” began to take shape in high school, when Denis attended a National Science Foundation ecology institute. There he read Eugene Odum’s Fundamentals of Ecology and studied dragonflies at a local pond, gaining an early appreciation for how nature functions as an integrated system.
Existential Crisis and Epiphany
During his first two years of college, Denis read far beyond his coursework — Charles Beard’s An Economic Interpretation of the Constitution, the anthology The God That Failed, and thinkers from Frantz Fanon and Julius Nyerere to Friedrich Hayek and Edmund Burke. He lost the religious faith of his youth and found himself intellectually alienated from the worldview that had shaped his first seventeen years — with nothing yet to replace it.
Searching for answers, he spent the next three years traveling through Asia, the Soviet Union, Europe, Africa, and the Middle East, often living on little more than oatmeal and peanut butter, struggling to reconcile the ideas he’d absorbed with the realities he encountered.
Then, in Namibia, everything came together.
After taking in the diversity of wildlife at water holes at Etosha Pan and learning about the German concentration camps that had stood at Shark Island, Denis found himself reflecting on the difference between natural predator-prey relationships and human cruelty. The following night, camping alone on the edge of the Namib Desert, he experienced a profound shift in perspective.
“I realized that in all my reflections on politics and economics, I had bought into the assumption that humans existed in a unique status of our own rather than as part of the web of life. In truth, we are animals — apex predators with large brains. The philosophies and policies I’d been studying could be greatly improved if they were informed by the principles of ecology that govern all life on Earth.”
That sleepless night, he found himself imagining concepts like urban ecology, industrial ecology, and ecological economics, years before those fields formally existed, and recognizing a profound interconnectedness of life that echoed the emerging Gaia Hypothesis.
“I’d rolled out my sleeping bag that evening confused and depressed,” he recalled. “But I arose the next morning with a sense of mission.” He had formulated a broad outline of the work to which he would devote his life: finding ways to integrate the principles of ecology into human affairs.
The Promising 70s
That sense of mission is what made him say “yes” to organizing the first Earth Day.
For Denis, it was never just about a one-time event — it was about building momentum toward real societal change. It worked: landmark legislation followed, including the Clean Air Act, Clean Water Act, Endangered Species Act, and other laws, along with pressuring President Nixon into creating the EPA.
Later, during the Carter administration, he led what became the National Renewable Energy Laboratory (NREL), believing solar photovoltaics could follow the same cost curve as other semiconductor technologies — growing cheaper as production scaled — “all without causing climate change, polluting the air, risking nuclear proliferation, or creating massive strip mines and oil spills.”
Environmental progress in the 70s was largely non-partisan and had great momentum, but in 1981 newly elected President Reagan terminated the solar commercialization program and fired Hayes.
Denis clearly feels the missed opportunity of where we might be today had that trajectory continued. One idea he still thinks about: “I believe America had a chance to pursue a constitutional amendment guaranteeing every person the right to a healthy environment. If initially interpreted by a Supreme Court that included Justices Douglas, Brennan, Blackmun, and Stevens, it could have had a massive, enduring impact.”
Going Global & Regional
With progress stalled in the U.S., Denis pivoted. In 1990 he took Earth Day global, founding the Earth Day Network, which grew to 180 countries and is now the world’s most widely observed secular holiday.
Frustrated by the gap between the landmark laws of the 70s and their real-world implementation, he took the helm of the Bullitt Foundation in 1992 to show how cities, buildings, and transportation systems could function more sustainably. “The Pacific Northwest is the greenest, richest, best-educated corner of the country. If we can’t turn Seattle, Portland, and Vancouver into ecological cities, where are we going to be successful?” While there, Hayes developed the Bullitt Center, widely regarded as the greenest commercial office building in the world.
Looking back, Denis described his career not as a smooth arc, but a roller coaster of successes and setbacks.
Expanding on His Deepest Motivations
Asked what values guide him most deeply, Denis placed himself within the broader social movements of the 1960s — anti-war, civil rights, women’s rights, and environmentalism. “[The environment] just happens to be where I settled, but not to the exclusion of social justice, peace, and respect for others.” It was part of a larger moral project.
Still, he believes environmental issues carry a unique moral weight, since some losses cannot be undone. “As the bumper sticker puts it, ‘Extinction is forever.’ If you change the climate of the planet, that’s not reversible — certainly not in any time period that’s relevant.”
On the emotional drivers of his work, he said “the things that drove me the most were a combination of hope and fear.” He described each environmental warning — overpopulation, climate change, AI — as a “self-undoing hypothesis” that motivates change by pairing the threat with a hopeful alternative.
“I have become more and more convinced that growth on a finite planet cannot continue indefinitely and that at some point the cost of growth becomes much larger than the benefits of growth.” He believes societies should strive to reach an equilibrium with humans flourishing—living comfortably, educated, and culturally enriched–versus a vastly larger population without those things. And he has devoted himself to finding pathways that let people thrive within ecological limits.
“More is different than better,” he emphasized.
An Enduring Mission
Looking back over Denis’ remarkable journey, the answer to what drives him seems surprisingly simple. Since that sleepless night in the Namibian desert, he has devoted his life to helping human society live within the ecological principles that govern the natural world. Every major chapter — Earth Day, renewable energy, sustainable cities — has been another expression of that same enduring mission.
Throughout his journey he has returned to the trees for renewal and perspective — especially the ancient redwoods of California and the old-growth forests of the Pacific Northwest — what he calls “my cathedrals.”
And he continues to ask the same question that first arose in a polluted mill town: isn’t there a better way?
Resource & Links
National Renewable Energy Laboratory
The Ethos Project 
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