Humanity has experience "immense" climate impacts across the world this summer, Guterres told media at the UN headquarters in New York ahead of the Kinshasa talks, which pave the way for COP27, the UN's 27th summit-level gathering on climate change, due to take place in Egypt next month.
"A third of Pakistan flooded. Europe's hottest summer in 500 years. The Philippines hammered. The whole of Cuba in black-out. And here, in the United States, Hurricane Ian has delivered a brutal reminder that no country and no economy is immune from the climate crisis," he said.
"We know people and nations are suffering now... Failure to act on loss and damage will lead to more loss of trust and more climate damage," the UN chief continued.
"This is a moral imperative that cannot be ignored and COP27 must be the place for action on loss and damage."
Delegates from over 50 countries are attending the two-day informal talks in Kinshasa, including US climate envoy John Kerry. The event winds up on Wednesday with side discussions.
No formal announcements are expected in what is billed as a ground-clearing exercise ahead of the next month's conference, taking place in Sharm el-Sheikh from November 6-18.
Greater support from wealthier countries, historically the world's biggest carbon polluters, to their poorer counterparts is expected to dominate the talks.