Cameroon’s former prime minister took over the presidency of the U.N. General Assembly on Tuesday, issuing “a clarion call” to the world’s divided nations to come together and take action to address global challenges from climate change and poverty to conflicts and armed violence.

Philemon Yang told the 193-member world body there are doubts that nations can join forces to tackle these and other pressing issues. But he said: “We must demonstrate that international cooperation remains the most effective tool at our disposal for addressing the profound and borderless issues we confront.”

Yang, a former diplomat who was prime minister of his West African nation from 2009 to 2019, said the cornerstone of his one-year presidency “will be built on the principles of unity in diversity.”

He said peace and security will continue to be “of paramount importance” during his presidency.

“This is why, I will urge the assembly to intensify its determination to prioritize the resolution of conflicts, including the intractable ones in the Gaza Strip, Haiti, and Ukraine, as well as find durable solutions to the situation in the Great Lakes region and elsewhere in Africa,” Yang said.

Outgoing General Assembly President Dennis Francis urged the United Nations, which was established on the ashes of World War II, to rise to meet its mandate — to maintain international peace and security.

“It is no understatement to say that the magnitude of manmade human suffering we are witnessing around the world is simply staggering,” the former diplomat and ambassador from Trinidad and Tobago said, pointing to Gaza and other conflicts.

But Francis also warned that millions of people live in abject poverty and hopelessness today, and “On our current trajectory, millions more will face poverty and hunger by 2030.”

U.N. Secretary-General Antonio Guterres also focused on the need for nations to work together.

He said the 78th session of the General Assembly, which ended Tuesday morning, was “a tumultuous year” of continued poverty, inequality, injustice, division, violence and conflict — and it was also the hottest year on record.

“But this session also closes at a time of growing hope and inspiration in what we can achieve if we work as one,” the U.N. chief said.

At Tuesday afternoon’s opening of the 79th assembly session, Guterres told diplomats: “Step by step, solution by solution, we can rebuild trust and faith in one another, and in what we can accomplish through collaboration and solidarity.”

Yang will preside at the upcoming gathering of world leaders at the General Assembly, first at the Summit of the Future on Sept. 22-23 called by the secretary-general to spur multilateral action on global issues — and reform global institutions founded after World War II including the United Nations.

Immediately after the summit ends, world leaders will hold their annual global meeting from Sept. 24-30, with public speeches in the assembly and lots of private meetings where a lot of the world’s business often gets done.