Dark clouds of factory smoke obscure Clark Avenue Bridge in Cleveland, Ohio, in 1973 — an example of the environmental crisis scientists were addressing at the time. Photograph, Frank J. Aleksandrowicz, National Archives and Records Administration collection

ON CHRISTMAS DAY 1966, A SNOWSTORM descended on Washington, D.C., and so did thousands of scientists. Most of them straggled into town late, delayed by snow-clogged roads, closed airports, and canceled train schedules along much of the East Coast. They were trying to work their way here by bus and car, plane and train, so they could attend the annual meeting of the American Association for the Advancement of Science (AAAS), the largest gathering of working scientists in the world. More than 7,000 in all would finally arrive, filling the city's three largest hotels.

On the day after that Christmas storm, a historian named Lynn White Jr. entered the huge ballroom in the Sheraton-Park Hotel and stepped up to the podium to give the conference's first end-of-the-day speech. It was a general-interest event scheduled for the evening to draw a large crowd. And it was supposed to be a big-picture lecture on how humans were changing the planet. The AAAS planning committee wanted the country's science community to begin thinking about causes and solutions for the world's growing environmental crisis.

White would not disappoint. His speech not only had a big-picture title, "The Historical Roots of our Ecological Crisis," it also had impact. The program for the week-long AAAS meeting would feature more than 400 separate sessions with more than 1500 speakers. The most widely remembered talk, however, would be the one given by White, a 60-year-old scholar with a full head of wavy gray hair, a penchant for suits with wide lapels, and a reputation as an authority on the rise of science and technology during the Middle Ages.

What the science community got from a medieval scholar was some unexpected thinking about a contemporary problem. The root causes for the environmental crisis, according to White, were not in our industries, not in the way they were exhausting natural resources, felling our great forests, fouling the air, or polluting the water in our rivers and bays and oceans. The causes of the crisis, said White, were in our heads, in the unconscious ideas that we carried through our lives. And for most people in Western societies, those ideas came from the Judeo-Christian religious tradition.

It was a prickly Christmas message White was delivering to leaders of the science community — and through them to leaders of religious communities around the country. It was a message White was willing to state with a boldness rarely seen in academic discourse. According to his analysis of the environmental crisis, the Judeo-Christian tradition "bears a huge burden of guilt."

The editors at the Washington Post knew a good story when they saw it. The next day they made White's speech the focus of their first story about the 1966 meeting. And they suspected another story was afoot, a story about changing relations between the science and religious communities, two groups that did not have a history of collaborating well. The paper noted that discussions about religion were a first at an AAAS convention — because religious inquiry was "generally believed to be irrelevant, if not inimical to scientific pursuits."

A change was brewing. Two months later White's speech about religion was published in Science magazine, one of the planet's most influential science journals, and that event elevated the importance of his controversial claims. His speech and his paper would unleash a post-Christmas storm, creating a debate that endures today about the connections between religion and science and the growing environmental crisis.

White's paper would eventually spawn dozens of books and hundreds of articles from historians and social scientists and religious scholars — most of them hoping to critique or even debunk White's argument. A funny thing happened on the way to the debunking. Many of the major Western religions began — over several decades — to re-examine their traditions, preparing the way for the rise of a religious environmental movement in many areas of the country, including the Chesapeake Bay region.

The man all these critics were trying to debunk was — ironically enough — the son of a Presbyterian minister. For his undergraduate work Lynn White Jr. attended Stanford University, but he earned his first graduate degree at the Union Theological Seminary in New York. And for his second graduate degree, a Ph.D. at Harvard, he spent months submerged in the archives of monasteries that flourished in Sicily during the Middle Ages.

Out of that early research White came to see monasticism as one of the wellsprings of Western technology. European monks believed that daily work was a form of worship and that creating new mechanical devices to speed their work was morally virtuous. As his career progressed, White became convinced that certain deep-seated values within Christianity not only spurred the growth of Western science and technology but also encouraged an aggressive stance toward nature that would have damaging consequences.

By the time he walked to the podium at the 1966 meeting of the AAAS, White was widely acknowledged as a pioneering historian. He'd written the classic work, Medieval Technology and Social Change, he'd already been president of the Society for the History of Technology, and he would soon be president of the History of Science Society. With this speech to the science community, he would win fame (and some infamy) that reached beyond the academic world — thanks to an argument that became known as "The Lynn White Thesis."

In stating his thesis, White cited the Creation story found in Genesis 1, the first chapter of the first book of the Bible, the most widely read book in Western civilization. Humans, according to Genesis 1, were created in the image of God: they were separate from nature. And they were given dominion over nature, over the plants and the animals and the earth. According to White those two ideas — separation and dominion — would create a heady, but hurtful mixture in Judeo-Christian religions.

Those ideas, he said, established a dualism between humans and nature that would lay the "psychic foundations" for the rise of Western science and technology. It was a dualism that energized scientists to investigate and probe and manipulate nature. Like the Bible, nature was a book to be read, another way to understand God's work, a way "to think God's thoughts after him." The attitude was common to Copernicus and Galileo and Newton — whose discoveries would undercut the religious worldviews of their eras.

As Judeo-Christian religions spread widely, they supplanted pagan religions that featured animistic beliefs. Pagan cultures may have altered their environment, but they did so believing there were spirits and souls alive in everything in nature — in animals, plants, rivers, mountains, the moon, and the sun. It was a vastly different way of looking at the world — and it was disappearing. "The victory of Christianity over paganism," said White, "was the greatest psychic revolution in the history of our culture."

While most forms of religious fervor disappeared from science during recent centuries, according to White, the underlying presuppositions — separation and dominance — still persisted in "a post-Christian world." They were still soaking our science and technology with what he called "orthodox Christian arrogance toward nature."

Two scientists played unusual roles in the rise of a religious environmental movement in this country: Lynn White Jr. (above, top) and Carl Sagan (above, bottom). White, a medieval historian, ignited a long-running debate when he said Judeo-Christianity tradition helped inspire the rise of Western science and create the current environmental crisis. Sagan, a famous astronomer, worked with other scientists in a campaign to persuade religious leaders to help solve the crisis. Photographs, Lynn White Jr., Imogene Cunningham, Special Collections, F.W. Olin Library, Mills College; Carl Sagan, NASA/Cosmos Studios.

The impact of that arrogance? Science and technology put new power in the hands of humans to manipulate nature and exploit the planet's resources. That power helped human societies feed, clothe, and shelter the planet's growing populations of humans. But all that science-powered exploitation often came with collateral damage: extinction of species, large-scale deforestation, disruptive forms of energy extraction, and the funneling of waste products and pollution into the air and rivers and estuaries and oceans.

The underlying assumptions about nature had changed for Judeo-Christian believers. The spirits that once animated trees, animals, and the earth had fled the scene. The sense of the sacred in nature had faded like an early morning mist.

By the 20th century, a sense of the sacred was replaced by a sense of unease about all this collateral damage wrought by human technologies. By the 1960s, unease was morphing into worries about an environmental crisis, and new environmental organizations formed in America, including groups like the Environmental Defense Fund, the Natural Resources Defense Council, Friends of the Earth, and Greenpeace. Lobbying by groups like this helped inspire a Clean Air Act, a Clean Water Act, an Endangered Species Act, and an Environ- mental Protection Agency.

These landmark legislations, however, came from an environmental movement that operated under secular, science-based leadership, and their victories were won with little input or help from the country's faith communities. By 1990, new worries about global warming led to calls for religious communities to help tackle the growing environmental crisis facing the planet.

One of those calls came from the science community. The astronomer Carl Sagan began recruiting dozens of well-known scientists, persuading them to sign a document he called "An Open Letter to the Religious Community." His message: it was time to resurrect a sense of the sacred in nature.

"The environmental crisis requires radical changes," Sagan wrote, "not only in public policy, but also in individual behavior." And that is where Sagan thought religion might supply something science could not. "Efforts to safeguard and cherish the environment need to be infused with a vision of the sacred." And religion, he said, could do better with that than science could.

It was a message likely to be heard. By 1990 Sagan was probably the most famous scientist in the country, the most widely quoted, and the most listened to. His science reputation was based on his work on topics like exobiology, the atmospheric conditions of nearby planets, and the "nuclear winter" that all-out warfare would create. His public fame came from writing popular books, from appearing regularly on the Tonight Show Starring Johnny Carson, and from writing and starring in Cosmos, the most widely viewed series in the history of public television. There were even websites keeping track of style changes for his floppy black hair.

Sagan had achieved the status of a science oracle with the American public, in part because of his ability to explain science in lyrical, poetic language, in part because he was willing — more willing than most well-known scientists — to risk his fame by taking public stands on controversial issues.

Any scientists who joined his crusade for religious environmentalism could expect their plea would be heard and their names would be known. The scientists who agreed to go public with Sagan included giants in a number of esoteric fields: Hans Bethe, the nuclear physicist, joined up; and so did Freeman Dyson, the theoretical physicist; Lynn Margulis, the evolutionary theorist; E.O. Wilson, the biologist who helped found the science of sociobiology; and Roger Revelle, the oceanographer who raised the first alarms about global warming.

On this issue Sagan was willing to do more than write a letter and recruit scientists. In January 1990, he flew to Moscow with Senator Al Gore, a politician who was a committed environmentalist, and they presented Sagan's letter from the science community to a global forum of religious leaders.

What did Sagan and his scientists want from the religious community? Nothing less than "a commitment in word and deed [Sagan's boldface] to preserving the environment of the Earth." His open letter read like a confession and an accusation: a confession that scientists were not solving the environmental crisis and an accusation that religious leaders weren't doing a very good job either.

The religious response to the science plea — at least at the national level — was immediate. A number of faith leaders said Sagan's call for religious action was "a unique moment in the relationship of science and religion."

In June 1991, several hundred religious leaders from five continents gathered in New York, meeting at the American Museum of Natural History and at the Cathedral of St. John the Divine. Over two days they debated and decided on a pledge they called "A Joint Appeal in Science and Religion." Created as a companion piece to Sagan's letter, the Joint Appeal committed the signers to specific steps towards educating their congregations about the environmental crisis and advocating for public policies to address it.

In 1990 Al Gore, a U.S. Senator from Tennessee, had already established a reputation as an environmentalist when he worked with astronomer Carl Sagan to encourage environmental activism by the country's major religions. In 1992 he would publish his book, Earth in Balance, shortly before being elected Vice President. Photograph, U.S. Sentate Historical Office

In 1992, a number of those leaders took the next step. Clergy and activists from the Jewish, Catholic, Protestant, and Evangelical faiths gathered in Washington, D.C., for a meeting organized by Paul Gorman, a vice president at the Cathedral of St. John the Divine. Under Gorman's approach, the leaders of each faith met first among themselves to discuss the perspectives on environmentalism found in their tradition. Next came interfaith discussions that included Sagan and Gore, followed by an eventual agreement to form and fund a National Religious Partnership for the Environment.

In 1993, all that planning launched three new religious environmental groups: the Coalition on the Environment and Jewish Life (COEJL), the Evangelical Environmental Network (EEN), and the National Religious Partnership for the Environment (NRPE).

What was going on? It was an abrupt awakening of the American religious establishment, said Gorman, speaking in a recent interview with the sociologist Peter Ellingson. It was a paradigm shift, says Cassandra Carmichael, the current leader of the National Religious Partnership for the Environment. "The NRPE," she says, "formed in response to scientists like Carl Sagan saying, we need you, we can't do this without you."

Why was an awakening needed? Many people sitting in the pews, it turned out, hadn't been hearing much guidance in their churches and synagogues and mosques. "You didn't hear anything about the environment. That wasn't even a consideration in how we lived," says Episcopal Bishop Eugene Sutton, who grew up in the nation's capital during the 1950s and 1960s.

What kind of advice was he hearing back in those pre-Earth Day decades? "Get the big gas guzzler! This was America! We were expanding," says Sutton. "You get things and then you throw them away."

It takes time, however, for an awakening among bishops and cardinals to trickle down to the pews. If religions were going to offer a faith-based, earth-friendly ethic, faith scholars were going to have go find it first. To get the theology right, the Harvard Divinity School held ten major faith conferences between 1996 and 1998. Organized by Mary Evelyn Tucker and John Grim, the meetings attracted more than 700 religious scholars, environmental activists, and grassroots leaders.

One result of all this rethinking was a shift in Biblical focus that downplayed the first chapter of Genesis (where Adam is given dominion) and refocused on the second chapter (where Adam is given duties). That's where Biblical passages about stewardship are found. "God took the human he had formed and placed him in the Garden of Eden to work it and to protect it," says Nina Beth Cardin. A community rabbi and environmental activist from Baltimore, Cardin wrote one of the more recent critiques of White's thesis. "In Genesis 2, in case you missed it, it tells you that we are here to take care of the earth."

That stewardship language is both a commandment and a warning. "And if we don't take care of the earth properly, we get booted," says Cardin. "And all of a sudden our Eden becomes all thistles and thorns."

To push this new thinking out to the pews, the national offices for each faith had to create stewardship tool kits and resource materials summarizing key environmental messages. According to Carmichael, environmental education packets went out to every Catholic parish, every synagogue, some 50,000 mainline Protestant and Eastern Orthodox churches, and 35,000 Evangelical congregations.

There was a dream behind this drive to awaken the churches. Religious activism helped abolish slavery, pass child labor laws, and create a civil rights revolution. It also supported anti-war and anti-nuclear campaigns and it now advocates for living-wage legislation. The new dream went like this: activating the churches could help environmentalism revolutionize American life.

By 1997, more than 70 independent religious environmental groups were active in the United States, according to sociologist Ellingson in a book-length study published by the University of Chicago Press. A new religious environmental movement was emerging around the country, he says, and it was spreading a "caring-for-Creation" ethic.

Historian Lynn White Jr. would not live to see the religious environmentalism that he helped spark with his Christmas-season speech back in 1966. His famous thesis linked religious ideas with the rise of science and the decline of the environment, and it cemented his reputation as one of the most original historians of his era — one scholar called his Science paper "one of the most important interpretations of history to come out of medieval studies in the second half of the 20th century."

St. Francis of Assisi (1182-1226) was a Roman Catholic friar who preached voluntary poverty and the human brotherhood with all the animals of the earth. He founded several religious orders including the Order of Friars Minor, now known as the Franciscan Order. Saint Francis of Assisi in Ecstasy, painting by Jusepe de Ribera, 1639

When White retired from academic life in 1974, UCLA named him University Professor in recognition of his groundbreaking work and his many awards. On March 30, 1987, he died of heart failure at 79 years of age.

During the last decades of his life, White saw a steady stream of critical articles and books and op-ed pieces come across his desk. Many of them quarreled with his claim that the cause of the crisis was Judeo-Christian concepts about man's dominion over nature. What drew less attention were White's ideas for solving the crisis.

The first step towards the ecological health of the planet, according to White, would be rejecting "the Christian axiom that nature has no reason for existence save to serve man." The second step would be finding an alternative. And here White, a life-long Christian, proposed a new patron saint for the age: St. Francis of Assisi, the saint who preached to the birds and spoke to the wolf and believed that men were part of a brotherhood in which all creatures, including Brother Ant, were equal. White called him "the greatest spiritual revolutionary in Western history." Why? Because he so clearly rejected "the idea of man's limitless rule of Creation."

The final irony of White's famous critique: since the root of the crisis was religious, the remedy would have to be religious. White said the solution did not require more science or technology. The remedy required a rethinking of our religious ideas.

History may yet convert the historian into a prophet. The rethinking of religion, which began during his lifetime, would elevate stewardship and caring for Creation into the core values of the emerging religious environmental movement.

Pope Francis was born in Argentina in 1936 as Jorge Mario Bergoglio. In 2013 he was elected the 266th Pope of the Roman Catholic Church and chose Francis as his papal name in honor of St. Francis of Assisi. In 2015, he issued his encyclical on the environmental crisis, Laudato si, rejecting the notion that humans have the right to absolute domination over other creatures. Photograph, CC BY-SA 2.0

Last year, when Pope Francis of the Roman Catholic Church issued his encyclical on the environmental crisis, he seemed to be channeling Lynn White Jr. from 50 years earlier. In offering guidance to the planet's one billion Catholics, Francis announced, "We must forcefully reject the notion that our being created in God's image and given dominion over the earth justifies absolute domination over other creatures." And the saint he cited in the encyclical was White's favorite: St. Francis of Assisi.

When he wasn't channeling White, the pope seemed to be answering Carl Sagan's call to restore the sacred in nature. Francis talked about "the mystical meaning to be found in a leaf, in a mountain trail, in a dewdrop, in a poor person's face." In the language of a Catholic pope, you could almost hear echoes of the animism that populates the natural world with spirits.

Sagan, the scientist who wanted to restore a sense of the sacred, would see the beginnings of the new religious environmental movement that his advocacy helped start. But only the beginnings.

In 1994, a black and blue mark appeared on his arm, and blood tests revealed myelodysplasia, a rare blood disorder that science could not cure. A skeptic who did not believe in religious deathbed conversions, he died two years later on December 20, 1996. He was only 62 years old.

Three memorial ceremonies were held for him, the last in New York at the Cathedral of St. John the Divine, an unusual site for remembering one of the world's most famous agnostics, but appropriate for a nonbeliever who called on the religions of the world to help science solve the environmental problems facing the planet.