He's been speaking at Quito's Catholic University in Ecuador, where he's currently on a nine day tour of the continent.
The pontiff picked up on themes from his recent encyclical on the environment when he said that God gave humanity the Earth to not only cultivate, but to look after.
"It is no longer a mere recommendation, but rather a requirement because of the harm we have inflicted on it by our irresponsible use and abuse of the goods with which God has endowed it," he said.
He also encouraged universities to make sure student education is not aimed only at profitable careers but also at helping the poor and the environment.
"There is a relationship between our life and that of mother Earth, between the way we live and the gift we have received from God," he said.
His talk at the university came after his second open air Mass which drew in crowds of over a million people.
He'll now move on to Bolivia and Paraguay before returning to the Vatican.