On a visit to Nepal's Everest area, where melting glaciers are threatening entire towns, UN Secretary-General António Guterres called on the world to "stop the madness" of climate change.
Nepal has lost about a third of its ice volume in the last 30 years, with glaciers melting at a rate that is 66% quicker than the preceding decade.
"The world's rooftops are caving in," the UN head added, adding that the "complete disappearance of glaciers" looms even larger.
"Glaciers are icy reservoirs; the ones in the Himalayas provide fresh water to over a billion people." River flows decrease as they recede," he remarked.
Glaciers high in the Himalayas maintain major river systems, agriculture, cattle, and local economies in an area with a population of about 1.8 billion people.
However, as global temperatures rise as a result of climate change, glacial snow ice that has been squeezed over ages is melting faster than ever - not only in the Himalayas, but also in critical locations like Antarctica and Greenland.
Mr. Guterres cautioned that key Himalayan rivers such as the Indus, Ganges, and Brahmaputra might see substantially lower flows in the future, decimating delta regions when combined with seawater.
"That spells catastrophe: Low-lying countries and communities erased forever," he went on to say.
According to the Secretary-General, his objective in the Everest region was to "cry out from the rooftops of the world."
"Stop the madness," he said, emphasising the need to put a stop to the age of fossil fuels in order to safeguard people on the front lines of climate change-induced catastrophe.
"To avoid the worst of climate chaos, we must act now to limit global temperature rise to 1.5°C." "The rest of the world can't wait," he concluded.
The UN Secretary-General is in Nepal at the invitation of the government.
Speaking to the media alongside Prime Minister Pushpa Kamal Dahal on Sunday, Mr. Guterres expressed his heartfelt condolences to the families of the ten Nepalese students killed in Hamas terror acts in Israel on October 7.
He restated his plea for the protection of all civilians in Gaza, as well as a call for an immediate humanitarian truce, the unconditional release of all captives, and the provision of long-term humanitarian aid on a scale sufficient to satisfy the needs of the Gazan people.