Pope's climate message puts US presidential hopefuls on the spot

Climate activists like Daniel Misleh, executive director of the Washington-based organisation, says he hopes Francis’ encyclical will generate a “serious, sustained dialogue” about the issue.

But Jeb Bush, who converted to Catholicism in 1995, drew a line between himself and the pope the day after the encyclical was leaked to the Italian press.

“I hope I’m not going to get castigated for saying this by my priest back home, but I don’t get economic policy from my bishops or my cardinals or my pope,” the Republican hopeful said on Tuesday on the campaign trail in the north-eastern state of New Hampshire.

“I think religion ought to be about making us better as people and less about things that end up getting in the political realm,” the former governor of Florida said.

Marco Rubio, another Catholic Republican contender who also hails from Florida, represents the southern state in the US Senate.

“I do not believe that human activity is causing these dramatic changes to our climate the way these scientists are portraying it,” Rubio told ABC broadcaster in May.

“I do not believe that the laws that they propose we pass will do anything about it, except it will destroy our economy.”

Rick Santorum, a Catholic from Pennsylvania, has dismissed evidence that humans have contributed to global warming as “junk science” and a ploy for more government control.

In the draft of the papal text leaked Monday by Italian weekly L’Espresso, Francis cites “a very significant scientific consensus indicating that we are facing a worrying warming of the climate system”.

Such warming is largely attributable to human activities, the pope writes. 

Francis is more in tune with the majority of Americans than many of the Republican contenders, according to a Pew Research Centre poll released this week. The poll found that 68 per cent of the public believes there is solid evidence that Earth’s temperature has been getting warmer over the past few decades and 46 per cent call it a very serious problem.

There is however a split between the political parties: Only 45 per cent of centre-right Republicans believe Earth is warming, and about half of them attribute it to human activity.

Among centre-left Democrats, 86 per cent believe Earth is warming, and three-quarters of that number attribute it to human activity.

Francis, the leader of the world’s 1.2 billion Catholics, is the first pontiff to dedicate an entire encyclical – the most important pastoral document a pope can issue – to the subject.

The encyclical may further burnish Francis’ anti-capitalist credentials in the eyes of critics and further estrange him from free-market conservatives, especially in the United States.

But Andrew Steer, president of the Washington-based World Resources Institute, says that he does not expect a strong backlash.

“I think it will lead hopefully in a really wonderful way to engagement in the moral aspects of the climate change imperative,” Steer says. “This will make it more difficult for politicians to either deny the problem exists or to imply that we shouldn’t seek to address it.”

Vatican officials insist that the encyclical is a religious, rather than a political document. But it is being published in the run up to papal speeches in September at the United Nations General Assembly headquarters and the US Congress.

It is also part of worldwide efforts to seal a new international agreement to reduce carbon emissions blamed for global warming in December in Paris.