He said people needed to change how they live their lives and called for "ecological responsibility" to be taught in schools.
The Pope said individuals and families had as important a role to play in preserving the environment as governments meeting at international summits such as the United Nations climate conference in Copenhagen last month.
He told thousands of faithful who had gathered in St Peter's Square that environmental responsibility was essential for global peace.
"I would like to underline the importance of the choices of individuals, families and local administrations in preserving the environment....