The Catholic Church has a troubled relationship with visionary science. In the 17th century, Galileo Galilei was censored by the church for supporting heliocentrism — the view that the Earth revolved around the sun, and not vice versa — and forced to disavow that heresy. Last week, Pope Francis confronted an equally visionary and divisive theory — man-made global warming — but this time the church has embraced the notion and called for swift action to save the planet.

"Laudato Si (Praise Be), On the Care of Our Common Home," is the first papal encyclical — a message from the pope to the faithful announcing his views on a critical issue — on the environment. Arguing that protecting the planet is a moral and ethical "imperative" that demands precedence over political and economic interests, Pope Francis is calling for "decisive action, here and now" to stop global warming.

The nearly 200-page missive acknowledges the "very solid scientific consensus" that the Earth is warming and that human behavior is the primary cause. The pope is calling for policies that drastically reduce greenhouse gas emissions through a "legal framework" that will defend the environment. This is a clear reference to COP 21, the United Nations Climate Change summit that will be held at the end of this year in Paris; the pope's advisers have said that the document seeks to influence those deliberations.