"We should all be alarmed by the escalation. Lebanon is at the brink. The people of Lebanon, the people of Israel, and the people of the world cannot afford Lebanon to become another Gaza."

War featured prominently in the UN chief's remarks, with references to Gaza, Lebanon, Ukraine, Sudan, and other ongoing conflicts.

"Nothing can justify the abhorrent acts of terror committed by Hamas on October 7, or the taking of hostages -- both of which I have repeatedly condemned," said the 75-year-old former prime minister of Portugal.

"And nothing can justify the collective punishment of the Palestinian people," he continued.

Humanity faces three major threats to sustainability that must be confronted, said Guterres: impunity, which erodes international law; inequality, which destabilizes nations; and uncertainty, "where unmanaged global risks threaten our future in unknowable ways."

Uncertainty, he said, was compounded by the existential threats of the climate crisis -- long a signature issue for the UN chief -- and the rapid advance of artificial intelligence, which he said would require a global approach to manage.

"We are in a climate meltdown," Guterres stressed, warning that the world is on course to "careen past the global limit of a 1.5 degrees (Celsius) temperature rise" -- a goal set by the Paris Agreement that scientists say is necessary to prevent the worst impacts from humanity's consumption of fossil fuels.

Still, he expressed hope, citing the plummeting costs and accelerating deployment of renewable energy, as he called on rich nations to step up their climate financing ahead of the COP29 meeting, which will take place in Azerbaijan this November.