A new survey finds fewer than half of Roman Catholics in the U.S. know about Pope Francis' bombshell teaching document on curbing climate change.

The poll also found that only a fraction of Catholics who were aware of the encyclical said they heard about it at Mass.

The survey was conducted by The Associated Press-NORC Center for Public Affairs Research and Yale University in July — a month after the pope released the encyclical.

In the document, Francis said climate change was a real and largely manmade moral emergency caused by an economic system that exploits the poor. He urged Catholics especially to take up his message.

Francis is expected to press his call for action on climate change when he visits the U.S. for the first time next month.