Pope Francis is encouraging people of different religions to work together to care for the Earth, which he calls our "common house."

Greeting people Sunday from his studio window, Francis praised a few hundred people who marched to St. Peter's Square under the banner "One Earth, one family."

Marchers included Christians, Muslims, Jews, Hindus and others. Their route began near the French embassy to remind people of an important climate change conference in Paris in December.

Francis said "I encourage the collaboration between persons and associations of different religions on behalf of an integral ecology." He offered good wishes to young people who are discussing "the care of the common house."

In a recent encyclical, or teaching document, Francis wrote passionately about the world's moral duty to save the Earth.