Pope Benedict XVI has criticised television and the internet for often portraying substance abuse, violence and sexual exploitation as entertainment.
He also told an international gathering of over 150,000 young people in Sydney that the Australian government had courageously apologised for injustices to the country's Aboriginal people.
Pope Benedict was speaking at the first Papal Mass of the World Youth Day festival that is held once every two years.
Over 800 Irish youths joined 150,000 others at Barangaroo, where Benedict spoke of a world scarred by the squandering of resources to fuel insatiable consumption.
The Irish group is supported by eight bishops, including Cardinal Sean Brady and Archbishop of Dublin Diarmuid Martin.
Pope Benedict said some pilgrims had come from islands threatened by rising water levels and others from drought-devastated nations.
He lamented alcohol and drug abuse, violence and sexual degradation and questioned how television's and the internet's frequent portrayal of these could be considered as entertainment.
Pope Benedict praised thousands of young Irish - and other European - missionaries for laying the foundations of much that is good in the Pacific region.
He said they became the humble but tenacious builders of so much of the social and spiritual heritage that still brings goodness, compassion and purpose to these nations.
