Australia, one of the world's highest per capita greenhouse emitters due to coal-fired power stations, is in the grip of the worst drought in 100 years and is struggling to save its major river system that feeds the nation's food belt.
APOLOGY TO ABORIGINES PRAISED
The pope also praised Australia for apologising for past injustices to Aborigines, saying it was a courageous move to repair race relations and offered hope to the rest of the world.
Rudd officially apologised to Aborigines in February.
Australia's 460,000 Aborigines make up about 2 percent of the country's 21 million population and have consistently higher rates of unemployment, substance abuse and domestic violence, as well as a life expectancy 17 years less than other Australians.
The pope thanked Aborigines for a traditional welcoming ceremony and acknowledged Aborigines are the first people of Australia.
"I am deeply moved to stand on your land, knowing the suffering and injustices it has borne, but aware too of the healing and hope that are now at work.," he said.
The Catholic Church hopes World Youth Day, the brainchild of the late Pope John Paul II, will revitalise the world's young Catholics at a time when the cult of the individual and consumerism has become big distractions in their lives.
The pope said the "social world" also had scars, highlighting alcohol and drug abuse, violence and sexual degradation. He questioned how the media's portrayal of violence and sexual exploitation can be considered "entertainment".
He warned young pilgrims "do not be fooled by those who see you as just another consumer".
