Pope Francis has called on the world’s rich nations to begin paying their “grave social debt” to the poor and take concrete steps on climate change, saying failure to do so presents an undeniable risk to a “common home” that is beginning to resemble a “pile of filth”.

The pope’s 180-page encyclical on the environment…is at its core a moral call for action on phasing out the use of fossil fuels.

But it is also a document infused with an activist anger and concern for the poor, casting blame on the indifference of the powerful in the face of certain evidence that humanity is at risk following 200 years of misuse of resources.

Up to now, he says, the world has accepted a “cheerful recklessness” in its approach to the issue, lacking the will to change habits for the good of the Earth.

“Climate change is a global problem with grave implications: environmental, social, economic, political and for the distribution of goods,” the papal statement says. “It represents one of the principal challenges facing humanity in our day.”

The encyclical, which can now be considered the church’s official position on the environment, includes practical guidance. Pope Francis rejects “simple solutions” to climate change such as cap and trade systems, which he says give rise to harmful speculation. He also dismisses any suggestion that population increases harm to the environment and should therefore be controlled, and resists making any judgment on genetically modified foods.

The essay was released following months of intense speculation about how far the pontiff would delve into a scientific realm that is still considered controversial in some countries such as the US, where views on climate change are divided along political lines.

Cardinal Peter Turkson, the pope’s top official on social and justice issues, flatly rejected arguments by some conservative politicians in the US that the pope ought to stay out of science.

“Saying that a pope shouldn’t deal with science sounds strange since science is a public domain. It is a subject matter that anyone can get in to,” Turkson said at a press conference on Thursday.

In an apparent reference to comments by Republican presidential contender Jeb Bush, who said he did not take economic advice from the pope, Turkson said that politicians had the right to disregard Francis’s statement, but said it was wrong to do so based on the fact that the pope was not a scientist.

You can read the Pope’s encyclical in the Vatican translation in several languages.

I’ve enjoyed great debates with religious folks about the basics of understanding reality, the material world – while we marched side-by-side on our nation’s capitol in Washington, DC. I’ve had truly enjoyable discussions about Jesus Christ as an Essene radical – while sharing a cell with a Catholic priest who always wore a fedora hat to demonstrations because he figured it made him look more like Bing Crosby, less likely to be clubbed by a cop. Disagreements about philosophy, material reality, don’t prevent adults from fighting for a common good.

Oh, and by the way, Jeb. The Pope has a technical degree in chemistry. How much science were you forced to study at UT?