Pope Francis urges world to protect the vulnerable during U.S. trip

Sweeping through New York CityFriday, Pope Francis offered comfort to families of the Sept. 11 victims at ground zero, warnings to world leaders at the United Nations and encouragement to children many of them immigrants at a Catholic school in East Harlem.

In the early evening, he led a jubilant parade through New York City'sCentral Park, smiling as he rode slowly in his open-sided Jeep past a cheering, shrieking crowd estimated at 80,000 people, many of them holdingcellphonesaloft in a sea of arms.

He then arrived at Madison Square Garden for an evening mass, with about 18,000 people attending the last event on the schedule for Day 4 of the Pope's six-day visit to the U.S.

"The Pope's positions always revolve around compassion and love you know, being a person for others," said DeniseVillasenor, 27, a Catholic Columbia University graduate student from the Philippines.

In his speech at the UN, the Pope decried the destruction of the environment through a "selfish and boundless thirst for power and material prosperity."

The environment itself has rights, and mankind has no authority to abuse them, said Francis, who hopes to spur concrete commitments at the upcoming climate-change negotiations in Paris.

He demanded immediate access for the world's poor to adequate food, water and housing, saying they have the right to lodging, labour and land.

Francis's speech, delivered in his native Spanish, received repeated rounds of applause from an audience that included German Chancellor AngelaMerkel, Bill andMelindaGatesas well as Nobel Prize laureateMalalaYousefzai.

Pope blesses ground zero

The ovations contrasted sharply with the moment of silent prayer during the Pope's visit later in the day to ground zero for an interfaith tribute to the Sept. 11 victims.

After praying before the waterfall pools that mark the spot where the twin towers once stood, Francis met with relatives of the 3,000 victims whose names are inscribed on the waters' edge.

Moving into the underground memorial museum, he joined a rabbi, an imam and other faith leaders to pray for peace, standing in front of the floodwall that became a symbol of New York City's resilience when it held fast after the attacks.

Among those on hand was MonicaIken-Murphy, whose husband, bond trader Michael PatrickIken, died in one of the towers.

"This is where loved ones lost their lives and this is the way we are going to honour them by having someone who is holy, closest to God.Pope Francis, come here and bless this site,"Iken-Murphysaid. "I couldn't be prouder to share this memorial and museum with him."

WATCH: Pope visits East Harlem school

9 years ago

Duration 2:26

Students and teachers excited to greet Francis at Our Lady Queen of Angels School in NYC

'Holy Father, we love you!'

Francis's afternoon schedule reflected the penchant of the "people's Pope" for engaging with the public, starting with a visit to Our Lady Queen of Angels School, set amid public housing in the heavily Hispanic neighbourhood of East Harlem.

A line of children shrieked and chanted, "Holy Father, we love you!" as he made his way along a barricade outside the school. A beaming Pope blessed them, shaking hands and posing for a few selfies. Some children embraced him, but a security guard intervened when one girl gave him a big hug.

After the morning's deadly serious activities, the 78-year-old Pope clearly perked up when he got to Harlem. He joked around with the children and chatted happily with them in Spanish.

The Pope who says he hasn't watched TV in decades and doesn't know how to work a computer even got a lesson in how to use a touchscreen from fourth-grader Kayla Osborne. The eight-year-old guided his hand to show him how it worked.

The crowd in the gym included about 150 immigrants and refugees, some of them in the U.S. illegally.

'It is beautiful to have dreams'

In his remarks, Francis recalled the Rev. Martin Luther King Jr.'s "I Have a Dream" speech.

"His dream was that many children like you could get an education," the Pope said. "It is beautiful to have dreams and to be able to fight for them."

The papal visit to the UN included a historic moment the Vatican flag was raised there for the first time. The UN General Assembly recently agreed to allow their two observer states, the Holy See and Palestine, to fly their flags alongside those of the 193 member states.

Although his UNremarks on the environment and the economy carried a message many liberals welcomed, Francis also affirmed church doctrine on abortion and sexuality.

Among other things, he called for the "absolute respect for life in all its stages," including the unborn.