In this handout picture taken and released on April 28, 2015 by the Vatican press office shows Pope Francis and United Nations Secretary General, Ban Ki-moon (R) holding a private meeting at the Vatican. AFP PHOTO / OSSERVATORE ROMANO.

This week — and it still feels strange to write this — the major climate change news story came out of the Vatican.

There, at the center of global Catholicism, church leaders joined with politicians, scientists and economists to draft a statement declaring not only that climate change is a “scientific reality” but also that there’s a moral and religious responsibility to do something about it. And an even more powerful statement is expected soon from Pope Francis himself, who is slated to release a major papal encyclical on the environment this summer.

All of this is enough to make environmentalists, members of a traditionally secular movement, nearly rhapsodic. After a history of being rather too technocratic and wonky, there seems to be a growing realization in green circles about the importance of an alliance with the world of faith.

This has been a long time coming. The effort to mobilize religious believers to worry about climate as part of a broader, biblically grounded “creation care” mandate has a long history (though it has traditionally focused more on evangelicals than Catholics). Books have been written about it, and one of its major spokespeople — Katharine Hayhoe, an evangelical climate scientist at Texas Tech University — was named one of Time magazine’s 100 most influential people last year.

And then there’s the 2014 biblical epic film “Noah,” whose director, Darren Aronofsky, called its subject the “first environmentalist.” It grossed more than $300 million worldwide with a message about the relationship between faith and saving the planet.

Despite all that, having Francis on board takes it all to a much higher level (pun intended). The reason, as David Roberts of Vox has written, is that it makes the climate debate moral, not scientific or technocratic. And when issues are moralized, people feel before they think and refuse to compromise. It may not be what we strictly call “rational,” but it is politically powerful.

Roberts notes that there has been a long history on the left of failing to adequately moralize the climate issue — and contrasts this with the growing movement across the country in which students are pushing their universities to divest from fossil-fuel stocks (which, Roberts argues, is an inherently moral stance). Actually, though, there is another important and oft-discussed example of a time when a leader chose not to moralize the climate issue — President Obama in 2008-2010.

Those were the days, during the Great Recession, when the White House tried to persuade the world to act on climate change through a message about “green jobs.” This was about the economy, the White House told us. And, it was about advancing new technologies — smart meters and wind farms and solar panels.

What happened is that we largely got the technology — and the ever-greening economy. Many would say it was politically impossible no matter the argument, but the fact was that climate solutions couldn’t make it through Congress.

Obama II on climate change, though, has often adopted a moral framing, making sure to talk about “our children,” our “grandchildren” and “future generations.” It still may not be enough to get any legislation through this Congress — and in his second term, the president may be less guarded and more frank in his approach — but it also reflects a broadly shifting message. And that’s important: Obama is pursuing controversial executive action to stem climate change, and winning the public on the question will be part of the battle.

The question remains, however, why this has been so long in coming. Why have environmentalists (and their scientific allies) been so focused on talking about policies like cap-and-trade, on tracking emissions targets and parts per million, rather than moralizing the issue?

Here, I think we need to turn to the research of social scientist Jonathan Haidt of New York University, famed for his insights about the different moral triggers and motivations of liberals and conservatives. One of the messages of Haidt’s book The Righteous Mind is that the left and the right tend to have different moral “foundations,” by which he means that they get emotional and intense about different kinds of moral situations.

In Haidt’s analysis, it isn’t that the left (or environmental left) lacks emotionality, but rather that conservatives sense a broader suite of moral foundations related to loyalty, respect for authority, and disgust — as well as the more typically liberal moral foundations related to fairness and protecting the vulnerable from harm. Haidt suggests that this gives conservatives a political advantage — but liberals can access moral emotions, too, and that it can be very powerful when they do so.

The moral emotion that is probably most relevant to the environment is what Haidt would call the “care/harm” foundation, and what many of us would simply call compassion or empathy. Recent research suggests that this emotion drives people toward environmental causes. There seems to be a deep connection between caring about other humans and then extending that to nature.

The Vatican, if the signs are to be believed, may blast this emotional channel wide open. Thus, the recent Vatican conference statement noted, “The poor and excluded face dire threats from climate disruptions, including the increased frequency of droughts, extreme storms, heat waves, and rising sea levels.” So it appears that a key part of the pope’s moral message may be that we must care for the environment because the very vulnerable depend on its sustainability and stability — for instance, how people living in low-lying areas will be exposed to greater flood risks in a future of rising seas and, maybe, stronger storms.

Another part of the moral message, as Yale Divinity School professor Teresa Berger told me recently,  may involve “the pope condemning sins of exploiting the Earth.”

So it has been long coming, but pope watchers in the environmental world are watching now for very good reason. They know this is the most powerful chance in a long time to make people care, and to create political will.