Just about every person who led and shaped the American conservation and early environmental movements grew up Protestant. What irony, then, that the one person who has done more to get people talking about the environment than anyone in decades is the supreme pontiff of the Catholic Church, Pope Francis.

Every pope since Paul VI has addressed environmental issues, but Francis’s encyclical this summer made many people aware for the first time of a Catholic concern for the environment. Even dedicated environmentalists might have a hard time naming a major Catholic environmentalist.

The average person could probably more easily name the seven Catholic Republican presidential candidates, who deny or downplay environmental problems like climate change.

Up through the 19th century, Protestant ministers wrote most of the great works about nature as the creation of God. The pantheon of great heroes of environmentalism is thoroughly Protestant — Henry David Thoreau, Theodore Roosevelt, John Muir, Aldo Leopold, David Brower, Rachel Carson, Edward Abbey. Exceptions have generally been Jewish, like Paul Ehrlich or Michael Pollan.

Francis’s encyclical framed global warming and environmental issues in a very Catholic way, in terms of their injustice to the poor. Since Vatican II in the 1960s, the Catholic Church has made social justice central to its teaching. It’s no accident, then, that the environmental justice movement is exactly where Catholics have participated most enthusiastically in American environmentalism.

The deeply devout Cesar Chavez might be said to have been the first major Catholic environmental leader in the late 1960s and 1970s, when his farm worker movement protested workers’ exposure to agricultural chemicals.

But the first Catholic to become nationally known for environmental activism was Lois Gibbs. Developers had built Love Canal, her neighborhood in Niagara Falls, N.Y., on top of 20,000 tons of buried toxic waste. Horrific health problems, especially for children, finally made headlines in 1978.

Gibbs organized homeowners and successfully led activists to demand government action. She went on to form and direct the Center for Health, Environment and Justice, a clearinghouse for local activists fighting problems of toxic waste.

After Love Canal, Catholic Latinos began to protest toxic pollution in their communities. Although the church hierarchy did not get involved, priests often joined the causes. Mothers of East Los Angeles scored notable successes in the late 1980s, defeating a toxic waste incinerator, for example. In another successful action, Tucson activists demanded that polluters clean up chemicals that contaminated groundwater under a Hispanic neighborhood.

In addition to environmental justice, other Catholics have advocated reverence for nature as the creation of God, which they see as the necessary foundation for environmental progress. Since the late 20th century, Catholic priests, friars and theologians, not Protestant clergy, have produced the popular works on God’s presence in creation.

Francis’s encyclical emphasized the need to recognize God as Creator and to see ourselves as part of interconnected creation. He cited French priest Pierre Teilhard du Chardin, who a century ago envisioned cosmic history as a grand unfolding of the divine plan, which works through evolution and ends with the salvation of humanity.

Teilhard’s philosophy has been popularized in America by his disciple Thomas Berry. Berry, a priest in the Passionist order who died in 2009, inspired his own Catholic followers Mary Evelyn Tucker and John Grim at Yale University and Brian Swimme. They believe that if people understood the Earth as the ongoing creation of God in a grand divine cosmological drama, we could begin the process of healing the Earth.

Two well-known Catholic writers and teachers have been Matthew Fox and Rosemary Radford Ruether, who took advantage of the freedom that Vatican II gave theologians to explore new directions. Fox, a Dominican friar (later defrocked by an increasingly conservative Vatican), advocated an ecstatic and mystical “creation spirituality.” Theologian Ruether was a major voice in the new field of eco-feminism, exploring the intersection of theology, feminism and environmentalism.

Aside from environmental justice and eco-theology, several Catholic religious orders have promoted environmental goals in their communities. They planted organic gardens or retrofitted buildings to make them more energy-efficient.

Inspired by the Earth-friendly prayers and sermons of their founder (and the pope’s namesake) St. Francis, Franciscans have been particularly committed. A movement among American nuns calling themselves “green nuns,” “eco-nuns” or “green sisters” has received a lot of attention. Many nuns have engaged in political activism or sponsored workshops on eco-theology or environmental justice.

The arrival of Pope Francis will raise renewed attention to the environmental crisis and to the plight of the poor. Perhaps, too, his visit will shine a spotlight on a half-century of American Catholic environmental thought and action, which in many ways has grown more vigorous than the environmentalism of Protestants.

Mark Stoll is associate professor of history and director of the Environmental Studies program at Texas Tech. He is author of “Inherit the Holy Mountain.”

Stay up to date on the papal visit. Sign up here to follow Washington Post stories about Pope Francis’s visit to the United States, and we’ll e-mail you as they’re published.

Want more coverage about faith? Sign up for the Acts of Faith newsletter.