Saving mankind from homosexual and transsexual behavior is just as important as saving the rainforest from destruction, said Pope Benedict on Monday.
In an end-of-year address to Vatican officials, the Pope said the Catholic Church "should also protect man from the destruction of himself."
A "sort of ecology of man is needed," he said.
The Catholic Church strongly opposes homosexual relationships and same-sex unions.
"The tropical forests do deserve our protection. But man, as a creature, does not deserve any less," he said in the address, which was later released to the media.
In an attack on transsexuals, the Pope said, "It is not man who decides who is a man or woman but God."
Non-heterosexual behavior was "a destruction of God's work," he said, adding that humanity needed to "listen to the language of creation" to properly define the roles of man and woman.