NEW YORK >>In person and on screen, world leaders returned to the United Nations’ foremost gathering for the first time in the pandemic era today with a formidable, diplomacy-packed agenda and a sharply worded warning from the international organization’s leader: “We face the greatest cascade of crises in our lifetime.”

Secretary-General Antonio Guterres rang the alarm in his annual state-of-the-world speech at the opening of the U.N. General Assembly’s high-level meeting for leaders of its 193 member nations. More than 100 heads of state and government kept away by COVID-19 are returning to the U.N. in person for the first time in two years. But with the pandemic still raging, about 60 will deliver pre-recorded statements over coming days.

“We are on the edge of an abyss — and moving in the wrong direction,” Guterres said. “I’m here to sound the alarm. The world must wake up.”

Guterres said the world has never been more threatened and divided. People may lose faith not only in their governments and institutions, he said, but in basic values when they see their human rights curtailed, corruption, the reality of their harsh lives, no future for their children — and “when they see billionaires joyriding to space while millions go hungry on Earth.”

Nevertheless, the U.N. chief said he has hope.

Guterres urged world leaders to bridge six “great divides”: promote peace and end conflicts, restore trust between the richer north and developing south on tackling global warming, reduce the gap between rich and poor, promote gender equality, ensure that the half of humanity that has no access to the Internet is connected by 2030, and tackle the generational divide by giving young people “a seat at the table.”

Other pressing issues on the agenda of world leaders include rising U.S.-China tensions, Afghanistan’s unsettled future under its new Taliban rulers and ongoing conflicts in Yemen, Syria and Ethiopia’s embattled Tigray region.

The three most closely watched speakers on this morning are U.S. President Joe Biden, appearing at the U.N. for the first time since his defeat of Donald Trump in the U.S. election last November; Chinese President Xi Jinping, who in a surprise move will deliver a video address; and Iran’s recently elected hardline President Ebrahim Raisi.

The General Assembly’s president, Abdulla Shahid of the Maldives, opened debate by challenging delegates to rise to the occasion. “There are moments in time that are turning points,” he said. “This is one such moment.”

In his speech, Biden, too, called this moment “an inflection point in history” and said that for the United States to prosper, it “must also engage deeply with the rest of the world.”

He urged “relentless diplomacy” and global cooperation on COVID-19, climate change and human rights abuses, pledged to work with allies, and said the United States is “not seeking a new Cold War.”

Biden was almost certainly responding to Secretary-General Guterres’ warning in an AP interview over the weekend that the world could be plunged into a new and probably more dangerous Cold War unless the United States and China repair their “totally dysfunctional” relationship.

The U.S. president’s pledge to work with allies follows sharp criticism from France, America’s oldest ally, for the Biden administration’s secret deal announced last week to provide nuclear-powered submarine to Australia with UK support, upending a French-Australia contract worth at least $66 billion to build a dozen French conventional diesel-electric submarines.

Ahead of the opening, Guterres warned the world could be plunged into a new and probably more dangerous Cold War unless the United States and China repair their “totally dysfunctional” relationship.

The U.N. chief said in an interview this weekend with The Associated Press that Washington and Beijing should be cooperating on the climate crisis and negotiating on trade and technology, but “unfortunately, today we only have confrontation” including over human rights and geostrategic problems mainly in the South China Sea.

Biden, in his speech, insisted he was “not seeing a new Cold War or a world divided” and said Washington is ready to work with any nation, “even if we have intense disagreement in other areas.”

French Foreign Minister Jean-Yves Le Drian told a news conference Monday that there is a “crisis of trust” between the United States and France, as well as Europe, which has been excluded from the new US-UK-Australia alliance focused on the Indo-Pacific and aimed at confrontation with China. He said Europeans “should not be left behind,” and need to define their own strategic interests.

On the latest speakers list released earlier this month, China’s speech was supposed to be delivered on Friday by a deputy prime minister. But the U.N. confirmed Monday that Xi will give the country’s video address instead. His speech and any comments about the U.S. rivalry are certain to be closely watched and analyzed: China’s presence in the world, and its relationship with the United States, affect most every corner of the planet.

By tradition, the first country to speak was Brazil, whose president, Jair Bolsonaro rebuffed criticism of his administration’s handling of the pandemic and touted recent data indicating less Amazon deforestation. He said he was seeking to counter the image of Brazil portrayed in the media, touting it as a great place for investment and praising his pandemic welfare program, which helped avoid a worse recession last year.

He said that his government has successfully distributed first doses to the majority of adults, but doesn’t support vaccine passports or forcing anyone to have a shot. Bolsonaro has said several times in the past week that he remains unvaccinated.

“By November, everyone who chooses to be vaccinated in Brazil will be attended to,” Bolsonaro told the General Assembly.

He also doubled-down on “early treatment” methods such as hydroxychloroquine, without naming the drug. Brazil’s government continued promoting the antimalarial long after scientists roundly dismissed it as ineffective against COVID-19.

Alarm over global warming was a common theme in speeches. Ibrahim Mohamed Solih, president of the tiny Indian Ocean island nation of the Maldives, said further rising temperatures are a “death sentence” for his country.

“One overarching fact remains. The state of environmental ruin small island states endure now, will without a doubt catch up with bigger nations sooner than later. There is no guarantee of survival for any one nation in a world where the Maldives cease to exist,” Solih warned.

Nonetheless, he said, : “This organization still represents the pinnacle of what concerted diplomacy can achieve.”

Guterres, in his opening speech, pointed to “supersized glaring inequalities” sparked by the COVID-19 pandemic, climate alarm bells “ringing at fever pitch,” upheavals from Afghanistan to Ethiopia and Yemen thwarting global peace, a surge of mistrust and misinformation “polarizing people and paralyzing societies” and human rights “under fire.”

The solidarity of nations to tackle these and other crises “is missing in action just when we need it most,” he said. “Instead of humility in the face of these epic challenges, we see hubris.”