ROME — Pope Francis has endorsed the science behind global warming and denounced the world’s political leaders for putting national self-interests ahead of action.

The 192-page leaked draft of a papal encyclical, published Monday by the Italian magazine L’Espresso, is an attempt to influence the debate before United Nations climate talks scheduled for the end of the year in Paris. Father Federico Lombardi, the pope’s spokesman, said the text was not the final one, which will be officially released midday local time Thursday by the Vatican.

The encyclical, titled “Laudato si (Praised Be) on the care of our common home,” is a call to action in the form of a letter to the church’s bishops. With fossil-fuel emissions and temperatures at record levels, the spiritual leader of 1.2 billion Catholics is adding his voice to calls to rein in greenhouse gases.

“International negotiations cannot progress in a significant way because of the positions of the countries which privilege their own national interests rather than the global common good,” the pope wrote. “Those who will suffer the consequences which we are trying to hide will remember this lack of conscience and responsibility.”

Francis squarely put the blame on humans, writing that many scientific studies show “the greater part of global warming in the last decades is due to the great concentration of greenhouse gases (carbon dioxide, methane, nitrogen oxide and others) emitted above all due to human activity.”

Reducing emissions, he wrote, demands “honesty, courage and responsibility, above all by the most powerful and most polluting countries.”

For months, the pontiff and his advisers have met dozens of scientists and economists to guide the church’s views on the topic.

The pope’s intervention already is rattling climate skeptics in the U.S. and giving environmentalists hope that the weight of his opinion could energize the agonizingly slow U.N. discussions.

“Francis has become the moral leader of our age, and he can do what scientists and national leaders cannot do,” Veerabhadran Ramanathan, professor of climate and atmospheric sciences at the University of California, San Diego, said in a phone interview.

“He can ask people, and not just Catholics, to change their behavior,” said Ramanathan, a senior member of the Pontifical Academy of Sciences that advises Francis.

A shift in the energy industry, which produces the majority of greenhouse gases, is already is underway. Investment in renewable energy ballooned to $310 billion last year from $60 billion a decade ago, according to data compiled by Bloomberg. The International Energy Agency says cleaner forms of energy will dominate power generation by 2030.

To help drive his message home, Francis has requested that bishops around the globe “accompany the publication with appropriate explanations and comments,” the Vatican said in a statement last week.

Francis himself will press his views on a visit to the U.S. in September. He will meet President Barack Obama and address Congress — the first pope to do so — and the U.N. General Assembly.

Rumblings about the encyclical already have drawn fire from critics in the U.S. — where the Republican chairman of the Senate Environment and Public Works Committee, James Inhofe, wrote a book on climate change titled “The Greatest Hoax.” Francis should “leave science to the scientists,” Republican presidential candidate Rick Santorum said this month.

“There are a significant number of devout Catholics who are Republicans, and those people will have to think very hard about his message,” said Andrew Steer, president of the World Resources Institute in Washington, who took part in a seminar on climate with Francis and several cardinals in May.

The title of the encyclical recalls the opening phrase of the “Canticle of the Creatures” by St. Francis of Assisi, who was the patron saint of animals and the environment. The pope chose to become Francis on his election in March 2013.