Photos taken by a mountaineer on Everest from the same spot where similar pictures were taken in 1921 have revealed an "alarming" ice loss.
The Asia Society (AS) arranged for the pictures to be taken in exactly the same place where British climber George Mallory took photos in 1921.
"The photographs reveal a startling truth: the ice of the Himalaya is disappearing," an AS statement said.
"They reveal an alarming loss in ice mass over an 89-year period."
Shrunken and withered
The photos taken by Mallory from the north face of Everest reveal a powerful, white, S-shaped sweep of ice.
Images taken from the same spot in 2010 by mountaineer David Breashears show that the main Rongbuk Glacier is shrunken and withered.
"Returning to the exact same vantage points, Breashears has meticulously recreated their shots, pixel for pixel," the AS statement said.
"The photographs illustrate the severity of the loss of ice mass among the glaciers surrounding Mount Everest."
The AS says that the findings are "vitally important" because the Himalaya is home to the world's largest sub-polar ice reserves.
"The melt waters of these high altitude glaciers supply crucial seasonal flows to the Ganges, Brahmaputra, Salween, Irrawaddy, Mekong, Yangtze and Yellow rivers, which hundreds of millions of people downstream depend on for their livelihoods," the statement said.
"If the present rate of melting continues, many of these glaciers will be severely diminished by the middle of this century."
Mr Breashears retraced the steps of the 1921 British Mount Everest Reconnaissance Expedition Team, using photos taken then by surveyor and photographer Maj Edward Wheeler and amateur photographer George Mallory, who later died attempting to reach the Everest summit in 1924.
"The melt rate in this region of central and eastern Himalaya is extreme and is devastating," Mr Breashears told an AS meeting in New York on Wednesday.
He has not only followed in the footsteps of Mallory but also those of Italian photographer Vittorio Sella, whose work spanned the 19th and 20th Centuries.
The result is a then-and-now series of photographs from Tibet, Nepal and near K2 in Pakistan - all of which show glaciers in retreat.
"If this isn't evidence of the glaciers in serious decline, I don't know what is," Mr Breashears told the AFP news agency.
The issue of melting glaciers in the Himalaya is controversial following a recent claim in a UN report by an Indian glaciologist - who later said that he had been misquoted - that they could all disappear by 2035.