A Vatican official who helped write a first draft of Pope Francis' upcoming encyclical on climate change acknowledged disagreement over the causes of global warming but said "what is not contested is that our planet is getting warmer" and Christians have a duty rooted in "ancient biblical teaching" to address the problem.

In a speech last week in Ireland, Cardinal Peter Turkson, head of the Pontifical Council for Justice and Peace, said Francis isn't making a political call to arms or an attempt at "greening the church." The pope instead is emphasizing Roman Catholic social teaching that links protecting life with fighting global inequality and preserving the environment, Turkson said.

"For the Christian, to care for God's ongoing work of creation is a duty, irrespective of the causes of climate change," Turkson said, in his address last Thursday at St. Patrick's Pontifical University in Maynooth, Ireland. "To care for creation, to develop and live an integral ecology as the basis for development and peace in the world is a fundamental Christian duty."

The highly anticipated encyclical is due to be released this June or July, and only the pope will determine what the final document will include. Still, Turkson's central role in drafting the statement is prompting many Vatican observers to consider the speech a preview of the encyclical.

Austen Ivereigh, author of the book "The Great Reformer" on Francis, called Turkson's talk a "curtain raiser" for the pope's eventual statement. Michael Peppard, a Fordham University theologian who has been closely watching Francis' statements on the environment, called the speech "a reliable indicator" of the direction Francis will take.

"Cardinal Turkson's talk, given at a pontifical seminary in Ireland, was for the whole church," said Bill Patenaude, a lecturer on Catholic teaching and the environment at Providence College in Rhode Island, and author of the blog Catholicecology.net. Patenaude said Turkson's council has been especially concerned about preparing the church and the public for the encyclical so that it can be properly interpreted, and this speech should be viewed as part of that preparation.

The text of the cardinal's address was posted at the website for the Irish bishops' conference. Citing the Book of Genesis, Turkson said Catholics "are called to protect and care for both creation and the human person."

"Clearly this is not some narrow agenda for the greening (of) the church or the world. It is a vision of care and protection that embraces the human person and the human environment in all possible dimensions," the cardinal said.

Turkson said the pope was "compelled by the scientific evidence for climate change," and the cardinal pointed to the synthesis report of the United Nations' Intergovernmental Panel on Climate Change. That study, released last November, found climate change is happening and it's almost entirely man's fault. Turkson acknowledged disagreement over the panel's findings but said "for Pope Francis, however, that is not the point." The cardinal said Francis was concerned with affirming "a truth revealed" in Genesis 2:15 on the sacred duty to till and keep the earth.

"He is not making some political comment about the relative merits of capitalism and communism. He is rather restating ancient biblical teaching," Turkson said. "He is pointing to the ominous signs in nature that suggest that humanity may now have tilled too much and kept too little."

Turkson argued that regulation alone won't stop global warming. He said a "changing of human hearts" is required and that religious teachings can "help to orient and integrate us as humans within the wider universe, to identify what is most important to us, what we revere, sustain and protect as sacred."