Republican presidential candidate Rick Santorum, a Catholic, describes himself as a “huge fan” of Pope Francis. Nonetheless, he thinks the Pope would do better to “leave science to the scientists” and stop talking about climate change. “I’ve said this to Catholic bishops many times—when they get involved with agriculture policy or things like that that are really outside the scope of what the church’s main message is, that we’re better off sticking to things that are really the core teachings of the church as opposed to getting involved with every other kind of issue that happens to be popular at the time," he said on a Philadelphia radio show this week. Instead, he urged the Catholic Church to "focus on what we're really good on, which is theology and morality. When we get involved with political and controversial scientific theories, then I think the church is probably not as forceful or credible."

But Santorum, who is not a scientist himself, has never hesitated himself to interpret climate scientist to suit his interests.

“Is the climate warming?" Santorum said on CNN in January. "Clearly over the past, you know, 15 or 20 years, yes. The question is, is man having a significant impact on that." He's questioned the well-established link between air pollution and diseases: "If you look at mercury ... there are particles all over the place. The question is, are they having any impact on public health?" He's even compared President Barack Obama's climate policies to a religion. “[Obama] is against fossil fuels, for his own, in my mind, quasi-religious reasons, which is not a rationale. If someone would go forward and put forth a religious idea as to how we should regulate the environment, and it was based on a Christian or other types of religious [ideas], they would be condemned up and down." (At least Obama's policies are grounded in science, unlike Santorum's rhetoric.)

This is an especially weak preview of the Republican pushback against the Pope's expected environmental encyclical June 16. It serves to remind voters of what House Speaker John Boehner, another Catholic politician, has said about the subject: That he cannot answer questions about climate change, because he's not a scientist. Usually, when politicians use this excuse, they then go on to question established science that humans are warming the planet.

Francis' encyclical isn't expected to be an education in science, exactly. The church is using its expertise precisely where it's needed, by making a moral argument that humans must think about their relationship with, and impact on, their natural environment.