"I have to apologise for being late", the smiling 82-year old pontiff told crowds of faithful patiently waiting for him to appear at his study window overlooking Saint Peter's Square.
"I was trapped in a lift for 25 minutes, there was a power outage and the lift stopped, but then the firemen came", the pope said.
He said he was rescued by Holy See firefighters and asked the people in the square to applaud them.
Francis issued the appeal in a message on September 1 to mark the start of several weeks of prayer by Christians to raise political awareness about pollution and exploitation of natural resources.
Twitter CEO Jack Dorsey's account hacked, racial and anti-Semitic messages tweeted
Twitter CEO Jack Dorsey's official account has been hacked and sending racist and vulgar tweets to his 4.2 million followers. Twitter users, of course, responded as they typically do - a mix of sarcasm and jokes while being questionably concerned.
"Let's give a round of applause to the fire service", he said, prompting cheers and applause from the crowd. Two are based in predominantly Muslim countries - Morocco and Indonesia.
The small private lift is known as the "little elevator of Pope Sixtus" because it links the courtyard named after the 16th century pope to the lavishly decorated papal apartment which Francis has shunned since his election in 2013.
Ten of the men are under 80 and eligible to vote in any conclave to elect a new Pontiff.