[ROME] Pope Francis called for an urgent, drastic cut in fossil-fuel emissions in an appeal to pull "Mother Earth" out of a "spiral of self-destruction" that he blamed on rich nations and the structure of the global economy.
The spiritual leader of 1.2 billion Catholics made his plea for the planet, and for the world's poorest people, in a 181- page encyclical - a letter to bishops and one of the major forms of papal writings - titled "Laudato si' (praised be) on care for our common home."
A sweeping document addressed "to all people of good will" and published in eight languages touches on science, theology and morality and weaves in views about politics and economics. It will stand as a key legacy of Francis's papacy.
For the Argentine pope, the encyclical is an attempt to pressure world leaders ahead of a United Nations summit on climate change in Paris at the end of the year. With preparations for a landmark deal on global warming hanging in the balance, Francis appealed "for a new dialog about how we are shaping the future of our planet."
The encyclical is the start of a long offensive that will see Francis weigh in repeatedly on climate change. He is due to press his views on a trip to Ecuador, Bolivia and Paraguay in July, and again on a visit to Cuba and the U.S.
The pope will tackle climate change when he meets President Barack Obama at the White House in September, and is expected to do so when he addresses the United Nations in New York.
The encyclical has already sparked controversy especially in the US, including among climate change skeptics in the Republican Party. Presidential candidate Jeb Bush, a Catholic, said this week, "I don't get economic policy from my bishops or my cardinals or my pope."
Francis gave Bush and other Catholics little room for maneuver, writing that Christians "realise that their responsibility within creation, and their duty towards nature and the creator, are an essential part of their faith." Vatican officials said the pope's pronouncements on the environment, born of Gospel teachings on creation, had the weight of doctrine.
Environmentalists and supporters of the UN climate talks, which are aiming to limit fossil-fuel emissions in all nations for the first time, hailed the pope's words as something that may spur ambitions.
"Pope Francis' encyclical underscores the moral imperative for urgent action on climate change," Christiana Figueres, the lead UN diplomat on climate, said in a statement from her office in Bonn. "This clarion call should guide the world towards a strong and durable universal climate agreement."
Francis backed the science behind climate change, and findings that it is man-made, writing that a number of scientific studies "indicate that most global warming in recent decades is due to the great concentration of greenhouse gases (carbon dioxide, methane, nitrogen oxides and others) released mainly as a result of human activity."
The pope wrote that "technology based on the use of highly polluting fossil fuels - especially coal, but also oil and, to a lesser degree, gas - needs to be progressively replaced without delay." Emission of carbon dioxide and highly polluting gases must be "drastically reduced" with urgency.
Francis could hardly have penned a more ambitious vision, writing that "it is we human beings above all who need to change. We lack an awareness of our common origin, of our mutual belonging, and of a future to be shared with everyone."
Sounding an apocalyptic tone, the pope wrote that humanity was behaving in at times "self-destructive" ways, and that once certain resources had been depleted "the scene will be set for new wars."
If present trends continued, this century could well see "an unprecedented destruction of ecosystems, with serious consequences for all of us." The pope analysed the impact of climate change on forests, polar ice-caps, water and biodiversity - and on the world's poorest and most vulnerable.
Humanity "has to hear both the cry of the earth and the cry of the poor," he wrote. "Huge consumption" by some rich countries caused global warming and hurt the poorest areas of the planet.
The pope called on politics and the economy "to acknowledge their own mistakes" on the environment and global poverty, denouncing those "who are concerned only with financial gain, and others with holding on to or increasing their power."
Trading carbon credits, he cautioned, "can lead to a new form of speculation, which would not help reduce the emission of polluting gases worldwide." The encyclical was little changed from a draft version that was leaked by the Italian magazine L'Espresso on Monday. The final version was released at midday in the Vatican on Thursday.
In the final version, the pope called for humility, and strove to sound an optimistic note. "We are not God. The earth was here before us and it has been given to us."
He added: "Humanity still has the ability to work together in building our common home."