Pope Francis issued a much-anticipated papal letter Thursday on the state of the Earth, decrying the modern "culture of waste" and warning of the "tragic effects of environmental degradation on the lives of the world's poorest."
He also decried the voracious consumerism of developed nations, and deplored what he said were moneyed interests seeking to obscure scientific knowledge of the problems and thwart necessary political action.
"Humanity is called to recognize the need for changes of lifestyle, production, and consumption," Francis said. The ecological crisis, he said, is a "summons to a profound interior conversion."
Reaction to the sweeping 192-page document was swift, with those alarmed about the health of the planet - including President Obama - praising Francis for speaking out, and skeptics of global warming saying it would not change their views.
Written in a direct and contemporary voice, the encyclical calls for "new dialogue about how we are shaping the planet," and takes aim at those who deny the problems are real.
The Earth, he said, is starting to look like "an immense pile of filth."
Titled 'Laudato Si': On Care for Our Common Home, the document is the first encyclical, or papal letter, addressing the environment in Catholic Church history.
Citing "very solid scientific consensus," Francis called climate change "a global problem with grave implications: environmental, social, economic, political, and for the distribution of goods."
He asserted that global warming is primarily man-made and is an oppressive burden on the poor that developed nations are morally obligated to reverse: "It represents one of the principal challenges facing humanity in our day" and calls for "changes of lifestyle, production, and consumption in order to combat this warming, or at least the human causes which produce or aggravate it."
Encyclicals are considered authoritative statements of teaching by the Catholic Church, but are not viewed as infallible.
'Laudato Si' takes its Latin title, which means "Praised Be," from a poem written in 1225 by the pontiff's namesake, St. Francis of Assisi.
Global warming is, however, just one the encyclical's many topics.
Francis also voiced concern about water quality and water supply, the effects of "agrotoxins," deforestation in the Amazon and Congo River basins, overfishing, the loss of plant and animal species as well as plankton, and the decline of coral reefs, aquifers, and glaciers.
While he praised those who fight to protect natural resources and who work for the poor, he also challenged those who advocate for population control by abortion.
"How can we genuinely teach the importance of concern for other vulnerable beings, however troublesome or inconvenient they may be, if we fail to protect a human embryo?" the encyclical asked.
"It is probably inevitable that 'Laudato Si' will get labeled 'the global-warming encyclical,' " said a conservative Catholic columnist, George Weigel. "But the label will be misleading."
President Obama said he "deeply admire[d] the pope's decision to make the case - clearly, powerfully, and with the full moral authority of his position - for action on global climate change."
The document appears timed to influence the U.N. summit on climate change in Paris in December, where governments are being asked to commit themselves to limiting greenhouse gas emissions.
"This could be a defining moment, one that could rally public opinion in a way that politicians can no longer ignore or resist," said Doug O'Malley, executive director of Environment New Jersey.
Francis may again raise his environmental concerns when he addresses a joint session of Congress on Sept. 24 and when he addresses the U.N. the next day.
Congressional Republicans gave the encyclical a chilly reception.
Sen. James Inhofe (R., Okla.), chairman of the Environment Committee, said global warming "alarmists" would use the encyclical to press for policies that would lead to tax increases that would hurt the poor most.
Rep. Rob Bishop (R., Utah), chairman of the Committee on Natural Resources, dismissed the letter as "rhetoric."
In his weekly column, Archbishop Charles J. Chaput of Philadelphia called 'Laudato Si' "a serious teaching document" possessing a "keen sense of justice" and a "desire to protect."
Rather than exhorting the faithful to embrace its message in its entirety, Chaput's letter noted the encyclical's "unusual level of scientific analysis and policy recommendations," and predicted it "will invite discussion."
Boston Cardinal Sean O'Malley said he welcomed the encyclical "with joy and gratitude."
The document was leaked Monday by an Italian newspaper and broadly circulated before its official release in Rome.
Its emergence over several days might have softened the impact (an incensed Vatican spokesman called the leak "heinous") and made it an early target for criticism by climate-change skeptics.
"I don't think we should politicize our faith," said Jeb Bush, a Catholic Republican who is running for president. "I think religion ought to be about making us better as people and less about things that end up getting into the political realm."
But Cardinal Donald Wuerl, archbishop of Washington, observed that "when you read the letter, you'll find there are no directives being given to politicians," or to financial or business leaders.
And Cardinal Peter Turkson, president of the Pontifical Council for Justice and Peace, which formally issued the encyclical, defended Francis' right to speak out.
"Saying that a pope shouldn't deal with science sounds strange, since science is a public domain," Turkson said Thursday at a news conference. He faulted those who sought to create an "artificial split between religion and public life, as if religion played no role."
Members of Pennsylvania's Democratic congressional delegation issued a joint statement praising Francis' call for action on climate change.
"We think it's only appropriate that one of the world's most influential religious leaders is speaking out about what we believe to be one of the most important moral issues of our time," it said.
Pope Francis: Laudato Si' excerpts
Saint Francis of Assisi reminds us that our common home is like a sister with whom we share our life and a beautiful mother who opens her arms to embrace us.
This sister now cries out to us because of the harm we have inflicted on her by our irresponsible use and abuse of the goods with which God has endowed her. We have come to see ourselves as her lords and masters, entitled to plunder her at will.
It is my hope that this Encyclical Letter, which is now added to the body of the Church's social teaching, can help us to acknowledge the appeal, immensity and urgency of the challenge we face.
If present trends continue, this century may well witness extraordinary climate change and an unprecedented destruction of ecosystems, with serious consequences for all of us.
Numerous scientific studies indicate that the major part of global warming in recent decades is due to the high concentration of greenhouse gas . . . emitted above all because of human activity.
Particular appreciation is owed to those who tirelessly seek to resolve the tragic effects of environmental degradation on the lives of the world's poorest. Young people demand change. They wonder how anyone can claim to be building a better future without thinking of the environmental crisis and the sufferings of the excluded.
There has been a tragic rise in the number of migrants seeking to flee from the growing poverty caused by environmental degradation. They are not recognized by international conventions as refugees; they bear the loss of the lives they have left behind, without enjoying any legal protection whatsoever. Sadly, there is widespread indifference to such suffering,
A sober look at our world shows that the degree of human intervention, often in the service of business interests and consumerism, is actually making our earth less rich and beautiful, ever more limited and grey.
[D]eterioration of the environment and of society affects the most vulnerable people on the planet.
As the United States bishops have said, greater attention must be given to "the needs of the poor, the weak and the vulnerable, in a debate often dominated by more powerful interests."
It is remarkable how weak international political responses have been. The failure of global summits on the environment make it plain that our politics are subject to technology and finance. There are too many special interests, and economic interests easily end up trumping the common good and manipulating information so that their own plans will not be affected.