Pope Francis demanded swift action on Thursday to save the planet from environmental ruin, urging world leaders to hear "the cry of the earth and the cry of the poor" and plunging the Catholic Church into political controversy over climate change.

In the first papal document dedicated to the environment, he called for "decisive action, here and now," to stop environmental degradation and global warming, squarely backing scientists who say it is mostly man-made.

In the encyclical "Laudato Si (Praise Be), On the Care of Our Common Home", Francis advocated a change of lifestyle in rich countries steeped in a "throwaway" consumer culture and an end to an "obstructionist attitudes" that sometimes put profit before the common good.

'Once more, we need to reject a magical conception of the market, which would suggest that problems can be solved simply by an increase in the profits of companies or individuals.'
- Pope Francis

The most controversial papal pronouncement in half a century has already won him the wrath of conservatives, including several U.S. Republican presidential candidates who have scolded Francis for delving into science and politics..

His appeal, however, won broad praise from scientists, the United Nations and climate change activists.

At a news conference presenting the landmark document, Cardinal Peter Turkson, one of Francis' key collaborators on the document, rejected pre-publication criticisms by U.S. politicians.

"Just because the pope is not a scientist does not mean he can't consult scientists," he said, adding with a sly smile that journalists write about many things after consulting experts.

Latin America's first pope, who took his name from St. Francis of Assisi, the patron of ecology, said protecting the planet was a moral and ethical "imperative" for believers and non-believers alike that should supersede political and economic interests.

The clarion call to his flock of 1.2 billion members, the most controversial papal document since Pope Paul VI's 1968 encyclical Humanae Vitae upholding the Church's ban on contraception, could spur the world's Catholics to lobby policymakers on ecology issues and climate change.

Political myopia

The Argentine-born pontiff, 78, decried a "myopia of power politics" he said had delayed far-sighted environmental action. "Many of those who possess more resources and economic or political power seem mostly to be concerned with masking the problems or concealing their symptoms," he wrote.

Vatican Encyclical

German scientist John Schellnhuber addresses the media during a press conference to present Pope Francis' environment encyclical, "Laudato Si" (Praise Be) Thursday. Schellnhuber said 'the science is clear: global warming is driven by greenhouse gas emissions.' (Andrew Medichini/Associated Press)

Because Francis has said he wants to influence this year's key U.N. climate summit in Paris, the encyclical further consolidated his role as a global diplomatic player following his mediation bringing Cuba and the United States to the negotiating table last year.

'Just because the pope is not a scientist does not mean he can't consult scientists.' - Cardinal Peter Turkson

Time was running out to save a planet "beginning to look more and more like an immense pile of filth" and which could see "an unprecedented destruction of ecosystems" this century.Francis dismissed the argument that "technology will solve all environmental problems (and that) global hunger and poverty will be resolved simply by market growth".

"Once more, we need to reject a magical conception of the market, which would suggest that problems can be solved simply by an increase in the profits of companies or individuals."

Francis also dismissed the effectiveness of carbon credits, saying they seemed to be a "quick and easy solution" but could lead "to a new form of speculation" that maintained excessive consumption and did not allow the "radical change" needed.

"Doomsday predictions can no longer be met with irony or disdain. We may well be leaving to coming generations debris, desolation and filth," he wrote in the nearly 200-page work.

"The pace of consumption, waste and environmental change has so stretched the planet's capacity that our contemporary lifestyle, unsustainable as it is, can only precipitate catastrophes, such as those which even now periodically occur in different areas of the world," he said.

"We need to reflect on our accountability before those who will have to endure the dire consequences."

The release and a high-profile roll-out including Professor Hans Joachim Schellnhuber of the Potsdam Institute for Climate Impact Research were timed to precede the pope's speeches on sustainable development in September to the United Nations and the U.S. Congress.

Schellnhuber said "the science is clear: global warming is driven by greenhouse gas emissions."

Scientific consensus

Francis, saying he was "drawing on the results of the best scientific research available," called climate change "one of the principal challenges facing humanity in our day" and said poor nations will suffer the most.

In several passages in the six-chapter encyclical, Francis confronted head on both climate change doubters and those who say it is not man-made.

"A very solid scientific consensus indicates that we are presently witnessing a disturbing warming of the climatic system," he said. "Humanity is called to recognise the need for changes of lifestyle, production and consumption, in order to combat this warming or at least the human causes which produce or aggravate it."

He said greenhouse gases were "released mainly as a result of human activity."

Francis called for policies to "drastically" reduce polluting gases, saying technology based on fossil fuels "needs to be progressively replaced without delay" and sources of renewable energy developed.

In a passage certain to upset conservatives, he said "a legal framework which can set clear boundaries and ensure the protection of ecosystems has become indispensable".

One of the major themes of the encyclical was the disparity of wealth.

"We fail to see that some are mired in desperate and degrading poverty, with no way out, while others have not the faintest idea of what to do with their possessions, vainly showing off their supposed superiority and leaving behind them so much waste which, if it were the case everywhere, would destroy the planet," Francis said.

He criticized those who "maintain that current economics and technology will solve all environmental problems, and argue, in popular and non-technical terms, that the problems of global hunger and poverty will be resolved simply by market growth."

A 'clarion call' and a 'stark reminder'

The U.N.'s top climate official, Christiana Figueres, called the pope's encyclical a "clarion call" that should guide world leaders to a "strong and durable" climate agreement in Paris at the end of the year.

The deal will be the first time all countries, both rich poor, agree to take climate action. But experts say the climate targets pledged so far won't suffice to keep global warming below 2 degrees C (3.6 F), the goal of the U.N. talks.

Figueres has long been arguing that transitioning to a low-carbon economy makes economic sense and has been trying to get corporate leaders aboard.

Welcoming the pope's message, she said that "coupled with the economic imperative, the moral imperative leaves no doubt that we must act on climate change now."

The World Bank says the pope's encyclical is a "stark reminder" of the link between climate change and poverty.

World Bank President Jim Yong Kim says climate change impacts, "including the increased frequency of extreme weather events, are most devastating for the unacceptably high number of people today living in extreme poverty."

He says that over the past 30 years weather-related disasters killed more than 2.5 million people and resulted in almost $4 trillion in damage.

"As the effects of climate change worsen, we know that escaping poverty will become even more difficult," he said. "Climate change also poses a direct risk to the hard-earned development gains over past decades."

WWF International President Yolanda Kakabadse said the pope's message "adds a much-needed moral approach" to the debate on climate change, which "affects the lives, livelihoods and rights of everyone, especially the poor, marginalized and most vulnerable communities."

With files from the Associated Press