As Pope Francis prepares a historic document to make environmental issues a priority for Catholics, a group of climate-change deniers is trying to convince the pontiff this week that global warming is nothing to worry about.

The Heartland Institute — a Chicago-based conservative think tank that has been attempting to discredit widely accepted climate science and prevent regulations to cut greenhouse gas emissions — says it wants to "inform Pope Francis of the truth about climate science."

"Humans are not causing a climate crisis on God's green Earth — in fact, they are fulfilling their biblical duty to protect and use it for the benefit of humanity," Joseph Bast, president of the Heartland Institute, said in a statement.

The group is sending a delegation to Rome this week to try to get Pope Francis to pay attention to its position with events Monday (April 27) and Tuesday (April 28). The Holy Father, meanwhile, is hosting a workshop on global warming Tuesday at the Vatican, which will includ U.N. Secretary-General Ban Ki-Moon and Harvard economist Jeffrey Sachs.

Pope Francis is drafting an encyclical (a papal letter that is sent to bishops of all the Roman Catholic churches) in which he is expected to declare that action on climate change is a moral imperative for the 1.2 billion Catholics around the world. The pope has been publicly speaking out on environmental issues over the past several months.

"I don't know if it [human activity] is the only cause, but mostly, in great part, it is man who has slapped nature in the face," the pope said, as quoted by the Associated Press, during a trip to the Philippines. "We have, in a sense, taken over nature."

The Heartland Institute's gripe with the pope might be emblematic of the rift that's opened between Pope Francis and some conservatives over hot-button issues in the culture wars. Last fall, he told a gathering of scientists that the Big Bang and evolution were not incompatible with religion. Some conservative Catholic groups were irked by the pope's more welcoming stance on gays and lesbians in the Church after he told reporters in 2013, "If they accept the Lord and have goodwill, who am I to judge them?"

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Among scientists who study the climate, 97 percent agree that humans are causing global warming, according to a 2013 study in the journal Environmental Research Letters. But among politicians, lobbyists and the public, this consensus seems to disappear. A recent investigation revealed that state environmental officials in Florida were informally banned from using the words "climate change" and "global warming." A 2014 poll from the Yale Project on Climate Change Communication found that 47 percent of Americans think global warming is caused mostly by human activities, and 23 percent don't think the climate is changing at all.

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