Pope calls for release of Hostages.

The pope calls for release of hostages in Korea. The pope calls for this and the pope calls for that. I must ask the question who gave him the authority to do this. When I look to my Bible I find no popes written about nor can I find anyone that's been given a higher authority except the apostles. In fact God is the only one with that high of authority next to his son who is our high priest and all Christians being priests. Anyone care to explain?