ROME - Pope Francis yesterday 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.

His appeal won praise from climate change activists, scientists and the United Nations (UN) as a moral imperative to governments to make 2015 a turning point in efforts to slow global warming.

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 bi-shops 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, it touches on science, theology and morality and weaves in views about politics and economics. It is likely to stand as a key legacy of Pope Francis' papacy.

For the Argentine Pope, the encyclical is an attempt to pressure world leaders ahead of a UN 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, Pope Francis appealed "for a new dialogue about how we are shaping the future of our planet".

The encyclical is the start of a long offensive that will see the Pope weigh in repeatedly on climate change. He is due to press his views on a trip to

Ecuador, Bolivia and Paraguay next month, and again on a visit to Cuba and the US.

The Pope will tackle climate change when he meets President Barack Obama at the White House in September, and is expected to do so again when he addresses the UN in New York.

The encyclical has already sparked controversy, especially in the United States where there are climate change sceptics in the Republican Party.

Presidential hopeful Jeb Bush, a Catholic, said this week: "I don't get economic policy from my bishops or my cardinals or my Pope."

Pope Francis gave Mr Bush, a Republican, and other Catholics little room for manoeuvre, writing that Christians "realise that their responsibility within creation, and their duty towards nature and the creator, are an essential part of their faith".

BLOOMBERG, AGENCE FRANCE-PRESSE