Some said they were wary about getting the church enmeshed in the debate over climate change, a contentious issue in the United States. They also expressed concern about allying with environmentalists, some of whom promote population control as a remedy, since the Church sees abortion and contraception as great evils.

Some bishops said they had received hate mail from Catholics skeptical of climate change. That has added to the bishops’ hesitation and confusion on the topic.

Cardinal Theodore McCarrick, the retired archbishop of Washington, D.C., said that at the meeting on Thursday, when the bishops discussed their top priorities for the coming years, “nobody mentioned the environment.”

“They don’t understand it. They don’t understand the complexities.” Cardinal McCarrick said of the bishops. He added, “When the encyclical comes out they’ll all get behind it, but they’re waiting to see what’s in it.”