In a major address before more than 200,000 people gathered in Sydney for the Roman Catholic Church's youth festival, the pope urged his more than 1 billion followers worldwide to resist various types of "poison" that are corroding society, and to care more for the environment.
"The concerns for nonviolence, sustainable development, justice and peace, and care for our environment are of vital importance for humanity," Benedict told the crowd massed on an unused wharf in Sydney. They regularly erupted in cheers, giving the event a football-match feel.
The pontiff emerged from three days at a secluded vacation spot to engage in a busy round of events for World Youth Day, a six-day festival held every few years to inspire new generations of Roman Catholics.
He received a series of welcomes: an official one from Prime Minister Kevin Rudd, a traditional one from pelt-clad Aboriginal dancers, and finally a rapturous one from pilgrims who journeyed to Sydney from more than 160 countries to attend. He toured the harbor by boat, cruising past Sydney's twin landmarks - its white-shelled opera house and the bridge nicknamed "the coat hanger" because of its shape.
Benedict's speech was his first major appearance at the festival and one of the main events of his 10-day trip.
He expanded on the theme that has resulted in his being dubbed the "green pope," noting that during his more than 20-hour flight from Rome to Sydney he had a bird's eye view of a vast swath of the world that inspired awe and introspection.
"Perhaps reluctantly we come to acknowledge that there are also scars which mark the surface of our Earth: erosion, deforestation, the squandering of the world's mineral and ocean resources in order to fuel an insatiable consumption," he said.
He recognized the problem of global warming.
"Some of you come from island nations whose very existence is threatened by rising water levels; others from nations suffering the effects of devastating drought," he said.
He said various poisons were also afflicting the world's social environment and corroding communities.
"Among the more prevalent are alcohol and drug abuse, and the exaltation of violence and sexual degradation, often presented through television and the Internet as entertainment," Benedict said.
At the official welcoming ceremony with Rudd, Benedict praised the Australian government for its "courageous" apology to the country's indigenous Aborigines for past injustices, saying it offered hope to all disadvantaged peoples who are seeking reconciliation.
Later, Aboriginal elders and dancers of the Gadigal clan, wearing white ochre body paint and animal pelts, gave Benedict a traditional welcome on what was once their land, now a park, on the harbor. They shook eucalyptus fronds as a symbol of cleansing and good fortune while someone played a didgeridoo, an Aboriginal wind instrument.
Aborigines are an often-marginalized minority of about 450,000 in Australia's population of 21 million. They are the country's poorest group, with the highest rates of unemployment, illiteracy, incarceration and alcohol abuse, and a life expectancy 17 years shorter than other Australians.
In February, Rudd formally apologized to Aborigines as one of his first official acts after taking power, and made closing the gap between indigenous and non-indigenous Australians a priority of his government.
Benedict's comments about Aborigines were not the first time a pope has recognized indigenous peoples.
In 2001, John Paul II issued a formal apology to the indigenous peoples of Australia, New Zealand and the Pacific islands for injustices perpetrated by Catholic missionaries.
Crowds of people thronged Sydney streets Thursday evening, shutting down a large part of downtown during rush hour, as Benedict drove in the popemobile through the city.
Security was tight, with thousands of police deployed and dark-suited security guards walking alongside the pope's vehicle. There was no sign of trouble.