Pope Francis's climate change missive leaked

Pope Francis describes the need to tackle man-made climate change as "urgent and compelling" in a leaked draft of a controversial letter on global warming.

The draft of the encyclical, titled Laudato Si (Praised Be), was published in Italian magazine L'Espresso yesterday and lays out the pope's much-anticipated views on the environment.

In the 191-page document, the pope affirms the scientific consensus which attributes global warming to human activity and speaks of an "ecological deficit" between peoples of the northern and southern hemispheres.

The official document is due to be published on Thursday and is likely to have a profound effect on the climate change debate. The pope is leader of an estimated 1.2 billion Catholics, who make up more than one in seven of the world's total population.

A Vatican spokesman described the leak as a "heinous act" and said the document was not the same as the final text.

The document is an encyclical - an official teaching document by the pope on a significant matter of doctrine. Encyclicals are usually addressed to members of the Catholic church, but Francis specifically addressed his letter to "every person who lives on this planet", according to a translation by the Wall Street Journal.

It comes ahead of a UN climate change summit in Paris later this year, where nearly 200 countries are expected to agree new targets to address the problem.

Siding with the environmentalist camp, Francis writes that there is a "very consistent scientific consensus that we are in the presence of an alarming warming of the climatic system".

The pope lays the blame for global warming largely at the feet of human consumption, writing that the main reason for the temperature increase over recent decades "is due to the great concentration of greenhouse gases (carbon dioxide, methane, nitrogen oxide and others) emitted above all due to human activity".

Francis has been outspoken on the topic of the environment throughout his two-year papacy. In December, the pope warned international delegates that "the time to find global solutions is running out" as they gathered for the UN's conference on climate change in Lima, Peru.

At an environmental summit held by a Vatican department in April, a Vatican statement said that man-made climate change "is a scientific reality" and tackling the problem is a "moral and religious imperative for humanity".

However, his intervention is likely to draw the ire of sceptics and the fossil fuel sector. Following the April summit, a spokesperson for the Heartland Institute, one of the top climate change sceptic groups in the US, told the Telegraph that the pope would be making "a grave mistake if he put his moral authority behind scientists saying that climate change is a threat to the world".

The American Petroleum Institute, which represents the US oil and gas industry, said it was working to review the leaked document, according to the Journal.

As well as championing the evidence for climate change in the letter, Francis also returned to the issue of social justice, a common theme of his time as pope.

He wrote that environmental problems "strike in a special way the weakest on the planet" and that northern hemisphere countries had exploited the resources of the southern hemisphere, such as Africa, creating an "ecological deficit".

The official document will constitute the pope's first independent encyclical. He contributed to an encyclical titled Lumen Fidei (The Light of Faith), published in June 2013, but the majority of the text was written by his predecessor, Benedict XVI, who retired in February 2013.