They compared pictures collected by a US reconnaissance programme with recent satellite data to measure the extent of glacial melt.
They believe the now-declassified images could help to show how other remote regions have changed over time.
The research was presented at the American Geophysical Union Fall meeting in San Francisco.
“This imagery will be getting used more and more,” said Josh Maurer from Columbia University in New York.
The images were taken by a United States spy satellite programme that went by the codename of Hexagon.
During the 1970s and 1980s, it launched 20 huge reconnaissance satellites into space, which secretly snapped areas of interest below.
The images were taken on rolls of film, which were then dropped by the satellites, and collected mid-air by passing military planes.
The material collected was declassified in 2011 and is now being digitised by the US Geological Survey (USGS) for scientists to use.
Among the spy images are pictures of the Himalayas, an area for which historical data is scarce. By comparing them with more recent satellite imagery from Nasa and Jaxa (Japanese Space Agency) scientists have been able to see how the region has changed.
“What we are trying to do is to quantify by exactly how much are the glaciers retreating, how much ice are they losing and at what rate,” said Josh Maurer.
“So we’ve used the images to extract 3D models of the terrain back in the 1970s.
“We can see the height of the glacier ice in 1973, and we take those elevation models, and can take the difference between those and the modern day elevation models, and we can work out how the ice volume is changing over time.”
The researchers have found that the extent of the ice loss has been great.
“At every point on the glacier surface across the whole of the Himalayas a quarter of a metre of water is being lost each year,” said Mr Maurer.
“I wouldn’t say it’s surprising given the climate data we have, but it is very very interesting to see how much ice is lost.
“And populations downstream where they depend on these water resources are going to be affected.
“As the glaciers shrink and retreat, the amount of run-off they provide to these streams will increase in the short term as they melt, but over the next 100 years it will decrease more and more, and that’s going to have a negative impact on water resources.”
He said that the images from the Hexagon programme are now being used by various research groups to track how other parts of the Earth have changed over time.
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Thomson, who is based in Gosport, was due to sail from France to Portsmouth Harbour this weekend after finishing second in the race last month.
But organisers called off the event as heavy rain and gale force winds have been forecast.
They said the event will be rescheduled for 11 or 12 February.
Bangor-born Thomson, 42, crossed the line 15 hours, 59 minutes and 29 seconds after winner Armel le Cleac'h - who set a record time of 74 days, three hours and 35 minutes.
Thomson had threatened to overtake Le Cleac'h with 309 miles left of the race before a malfunctioning autopilot ended his challenge.
He has now matched Dame Ellen MacArthur as the best British competitor in the Vendee Globe. She finished second in the 2001 race.
Thomson is expected to sail his boat Hugo Boss, surrounded by a flotilla of craft, in a parade down The Solent into Portsmouth.
Hundreds of fans are expected to attend the celebrations in the city and at Thomson's team base at Haslar Marina.
Organisers said full details of the rescheduled celebrations will be announced next week.
Scientists have used Cold War spy satellites to reveal the dramatic environmental changes in the Himalayas.
[NEXT_CONCEPT]
An event to mark the achievements of sailor Alex Thomson in the round the world Vendee Globe race has been postponed due to forecast storms.