The pope’s climate encyclical is scheduled to drop June 18. Just in time for summer beach reading!

I grew up in the suburbs of Detroit, in neighborhoods filled with what felt like a United Nations of Catholics (Polish, Ukrainian, Irish, Chaldean, Greek, among others). I was impressed both at how my neighbors loved the pope — but also with how they deftly worked around those aspects of Catholicism that didn’t work with their actual, day to day lives.

The man who owned the tool and die shop that my dad worked at was in raptures over the fact that, once, when the pope had visited Detroit, he had been given the sacred task of carrying the pope’s luggage. Meanwhile, based on the mom-to-mom chatter that I overheard in the playground and at baby showers, very few Catholic mothers were on the same page with the pope when it came to the rhythm method as a moral form of family planning. To the moms, the pill was perfectly moral, and the pope didn’t know what he was talking about. They weren’t all with Flo Kennedy on the “If men could get pregnant, abortion would be a sacrament” tip (though a few were). They did know — from experience, since most of them had grown up in large, pre-pill Catholic families —  that the pope wasn’t going to be the one raising all those baby Catholics.

So this climate encyclical is a chance to ask the question: How much sway does a religious leader like the pope really have over the Catholics of this world? What if our cute new, selfie-posing, bus-riding, named-after-St. Francis-of-Assisi pope — who has already said that Catholics have a “moral obligation” to cut carbon emissions — came down as hard on driving as the church has on, say, birth control? What if the pope told Catholics to take public transit for one day every week?

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According to the Vatican, about 17.5 percent of the world’s population is Catholic. About a quarter of the U.S. population self-identifies as Catholic. If those people all became regular transit users, it would be a game-changer for transit across the country.

But let’s not stop there. What if the pope put out the word that all Catholic churches, schools, hospitals, and soup kitchens had to become carbon-neutral, or had to plant food gardens for the public, or even just had to start composting? What if the pope told American bishops to stop trying to ban vasectomies in Catholic hospitals? Catholics may love the pope, but would they listen to the guy? I mean, it’s totally possible to love someone and still not do anything they tell you to.

I did manage to dig up one scientific example of a Catholic edict having a very clear environmental effect. In 1966, Catholic bishops in the United States announced that Catholics don’t have to eat fish on Friday anymore (though they did still have to during Lent). In the nine months after the new decree, fish prices in New England fell by 12 percent.

The move didn’t exactly protect the global fish supply — the Filet-O-Fish, for example, which was created to keep Catholics coming in to McDonalds on Fridays and during Lent, still exists. But it did have a measurable effect. And that was just the U.S. bishops doing the work –not even the pope.

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Rick Santorum, the Catholic conservative ex-senator whose day job for many years has been presidential candidate, has gone ahead and pre-criticized Pope Francis for even contemplating a big push on climate change. “The church has gotten it wrong a few times on science,” Santorum told Philadelphia’s  WPHT 1210 host Dom Giordano. “We probably are better off leaving science to the scientists and focus on what we’re really good at, which is theology and morality.” Actually, despite being total jerks to Galileo, the Catholic church has made substantial contributions to science — particularly Pope Francis’ peeps, the Jesuits. (Also, if we left the issue to the scientists, we’d have taken major action to head off climate change long ago — and ignored Santorum and his faction.)

Which brings us to another example of a papal edict having a very broad effect on American culture. One of the great Catholic scientists in recent history is the physician John Rock, who devoted himself to helping developing the birth control pill, precisely because Rock hoped that a birth control method that worked with something as basic and god-given as the hormonal cycle would fit into the Vatican’s strict rules on family planning.

It didn’t work. Rock was personally devastated by Pope Pius XII’s reassertions of the prohibition on all forms of birth control, decades after the Anglican church and most other denominations had given it a seal of moral approval. In America, at least, Catholics and Protestants don’t vary too much from each other when it comes to family size, even though Catholic doctrine has much stricter rules concerning both. But Catholic influence in politics and the nonprofit sector has continued to make family planning expensive and difficult for all Americans, regardless of political affiliation.

The pope didn’t always have this much power. The doctrine of “papal infallibilty” (literally, “the pope can never be wrong”) only dates back to the First Vatican Council of 1870 — before that, the pope’s power was balanced by powerful church councils and national assemblies.

It’s hard to think of an issue more suited to the core tenets of Christianity than climate change. Dealing with climate change, and mitigating the damage that it has already caused, requires challenging the status quo and sacrificing personal comfort in order to help people, without any guarantee that those people will ever know how heroic and thoughtful you are. The papacy has stumbled in the past in the face of great moral choices: the Holocaust was one example; the embrace of authoritarian regimes that liberation theology opposed was another; and of course there was the decades-long-coverup of sexual abuse by clergy.

Commentators more experienced in the ways of the pope than I have also made the point that, in general, while what the pope says has very real political results, he is more preacher than policy wonk. The encyclical is likely to be an appeal to individual Catholics to look at their lives and try to live more sustainably. What happens with it will ultimately depend on how different Catholics around the world interpret that statement. There is a long history, for example, of some Catholic colleges openly challenging the church’s stance on birth control.

St. Francis is not the first pope with environmental leanings. Pope John Paul II called on humanity to “repent” for its mistreatment of the environment back in 2002, with little noticeable effect. Pope Benedict XVI worked to make Vatican City the first carbon-neutral state and talked about ecology so much that he was nicknamed “the green pope” — but again, without creating a broader movement. If either of them had come up with something simple and clear, like “no meat (except fish) on Friday,” would the story have turned out differently?

While speculation is rampant over what the encyclical will say, it’s time to talk about what a Catholic Church that took its environmental ideals and applied them to the everyday of its members would actually look like. Climate change could be a chance for the papacy to — well — redeem itself.