Pope Francis arrives at the U.N. on September 25, just hours ahead of the opening of a major anti-poverty summit. He will address the U.N. staff and have a private meeting with Secretary-General Ban Ki-moon, whom he has met three times before at the Vatican.

“We have been discussing many issues, including poverty eradication and migration, refugee issues, last time, and most importantly, climate change,” said Ban.

The pope will then give a highly anticipated address in the General Assembly Hall.

“Remarkably, he seems to have emerged as a real voice of global moral authority on things like refugees and climate change.  A lot of people will be looking to him and what he has to say about the state of the world,” said Carne Ross, a diplomatic consultant.

Then it’s down to business with the world’s toughest problems.

Richard Gowan of Columbia University predicted the migrant crisis in Europe and the Islamic State group would be major agenda items.

“There is going to be a lot of self-congratulation about the Iran nuclear deal, but that will be overshadowed by the humanitarian crisis in Europe and the continued power of the Islamic State in the Middle East,” Gowan said.

On September 30, there will be a high-level meeting on the refugee crisis in Europe. The secretary-general says he hopes to mobilize a humane and effective response. 

The majority of refugees are Syrians, fleeing four and a half years of civil war.  

Russia’s recent increase in military support to Syrian President Bashar al-Assad has raised tensions with Washington.  President Vladimir Putin, who has not attended a General Assembly in nearly a decade, may bring a new strategy on Syria, but it may not be to everyone’s liking.  

“There is a fundamental division with the U.S. and Europeans over Assad, and Moscow’s continuing support for Assad, so it’s likely to be a diplomatic breakdown rather than a breakthrough,” Gowan said.

President Obama will preside over a meeting on combatting terrorism.

“The president is going to convene a meeting to look at countering violent extremism, to look at what the coalition has achieved and where the gaps are,” said Samantha Power, the U.S. ambassador to the U.N.

This year’s General Assembly may be the biggest ever, both in terms of leaders and challenges.