PARIS -- Some of the world's most famous glaciers, including in the Dolomites in Italy, the Yosemite and Yellowstone parks in the United States and Mount Kilimanjaro in Tanzania will disappear by 2050 due to global warming, whatever the temperature rise scenario, .

The United Nations cultural agency UNESCO monitors some 18,600 glaciers across 50 of its World Heritage sites and said that a third of those are set to disappear by 2050.

While the rest can be saved by keeping global temperature rise below 1.5 degree Celsius (2.7 Fahrenheit) relative to pre-industrial levels, in a business-as-usual emissions scenario, about 50% of these World Heritage glaciers could almost entirely disappear by 2100.

World Heritage glaciers as defined by UNESCO represent about 10 percent of the world's glacier areas and include some of the world's best-known glaciers, whose loss is highly visible as they are focal points for global tourism.

The report's lead author Tales Carvalho told Reuters that World Heritage glaciers lose on average some 58 billion tons of ice every year 鈥� equivalent to the total annual volume of water used in France and Spain together 鈥� and contribute to almost 5% of global observed sea-level rise.

Carvalho said that the single most important protective measure to prevent major glacier retreat worldwide would be to drastically reduce carbon emissions.

UNESCO recommends that given the inevitable further shrinking of many of these glaciers in the near future, local authorities should make glaciers a focus of policy, by improving monitoring and research and by implementing disaster risk reduction measures.

"As glacier lakes fill up, they can burst and can cause catastrophic floods downstream," Carvalho said.