In 2007, Pope Benedict told a youth gathering that world leaders must make bold decisions to protect the environment "before it's too late." This meeting was the first "Eco-Friendly" Catholic meeting in the world. There were almost 500,000 people there.
"We need a decisive 'yes' to protect creation, and also a strong commitment to reverse the bad environmental trend," the pope said.
He was wearing green undershirts and he was talking to a crowd of young people on a hillside near the Adriatic town of Loreto. On this day the Italian Catholic Church celebrates its annual Protection of Creation Day.
More than 300,000 people slept on blankets and in tents, and other people prayed through the night. Organizers said 200,000 more turned up on Sunday from all over Italy.
"New generations will be entrusted with the future of the world, from which we can now see that development has not always protected the environment," the pope said from a white stage.
In 2008 the Vatican ruled that drugs, pollution, genetic engineering and even social and societal injustices are now sinful behaviors.