Glaciers at many UNESCO World Heritage sites including Yellowstone and Kilimanjaro National Park will likely vanish by 2050, the UN agency warned Thursday, urging leaders to act fast to save the rest.
The warning followed a study of 18,600 glaciers at 50 World Heritage sites -- covering around 66,000 square kilometres (25,000 square miles) -- which found glaciers at a third of the sites were "condemned to disappear".
The glaciers were losing 58 billion tonnes of ice every year, equivalent to the combined annual water use of France and Spain, and were responsible for nearly five percent of observed global sea-level rise, the agency explained.
"Glaciers in a third of the 50 World Heritage sites are condemned to disappear by 2050, regardless of efforts to limit temperature increases," UNESCO said.
"But it is still possible to save the glaciers in the remaining two thirds of sites if the rise in temperatures does not exceed 1.5°C compared to the pre-industrial period."
Countries have pledged to keep global warming to 1.5 degrees Celsius above pre-industrial levels -- a goal the world is set to miss on current emission trends.
"This report is a call to action," said UNESCO head Audrey Azoulay, ahead of the COP27 climate summit in Egypt starting on Monday.
In Africa, glaciers in all World Heritage sites will very likely be gone by 2050, including at Kilimanjaro National Park and Mount Kenya, UNESCO warned.
In Europe, some glaciers in the Pyrenees and in the Dolomites will also probably have vanished in three decades' time.
The same went for glaciers in the Yellowstone and Yosemite national parks in the United States.
The melting of ice and snow is one of the 10 key threats from climate change, an Intergovernmental Panel on Climate Change report published in February said.