The UN chief summons world leaders to action. But, he says, they seem 'incapable of coming together'

Insisting that international cooperation is critical, the United Nations chief delivered a dire warning to leaders from across the world Tuesday, declaring that the planet is becoming unhinged with mounting global challenges and geopolitical tensions -- and warning that "we seem incapable of coming together to respond."

Insisting that international cooperation is critical, the United Nations chief delivered a dire warning to leaders from across the world Tuesday, declaring that the planet is becoming unhinged with mounting global challenges and geopolitical tensions -- and warning that "we seem incapable of coming together to respond."

Addressing presidents and prime ministers, monarchs and ministers at the opening of the UN General Assembly's high-level meeting, Secretary-General Antonio Guterres ticked off a list of "existential threats" the world is facing, from climate change to disruptive technologies like artificial intelligence.

"Our world is becoming unhinged. Geopolitical tensions are rising. Global challenges are mounting. And we seem incapable of coming together to respond," Guterres told the people who run the world's nations. He said that the United Nations -- and the ways that countries cooperate -- must evolve to meet the era.

"The world has changed. Our institutions have not," Guterres said before the opening of the UN General Assembly's General Debate. "We cannot effectively address problems as they are if institutions don't reflect the world as it is. Instead of solving problems, they risk becoming part of the problem."

All this is taking place. Guterres said, as the world is making a "chaotic transition" and rapidly moving from a brief period of "unipolarity" -- domination by a single power, the United States -- toward a multipolar world with many power centers. That is, he said, positive in many ways.

Guterres said a multipolar world needs strong, effective multilateral institutions where all countries work together to solve the world's challenges. But the current institutions formed on the ashes of World War II, including the United Nations and its powerful Security Council and key global financial institutions, have not changed enough.

If these institutions are not reformed to reflect the world today, Guterres said the alternative is not maintaining the status quo; it is "further fragmentation." He added: "It's reform or rupture."