Glaciers in the Himalayas are melting at double the pace, according to researchers who have used Cold War spy satellite images to compare the conditions back then to now.
Scientists compared old photographs of glaciers taken during a US spy program with recent spacecraft observations and found that melting in the area has doubled over the past 40 years.
The researchers think their study provides evidence that the rising temperatures caused by climate change are ‘eating’ the Himalayan glaciers.
This dramatic glacier loss is horrifying because it could threaten water supplies for hundreds of millions of people across Asia and result in droughts and water shortages.
The study used 40 years of satellite observations across India, China, Nepal and Bhutan to determine that glaciers in this area have been losing a foot and a half of ice each year since 2000, which is double the amount of melting that took place between 1975 and 2000.
“It is the clearest picture yet of how fast Himalayan glaciers are melting over this time interval, and why,” said lead study author Joshua Maurer, from Columbia University.
Historical data for the Himalayas is hard to come across as barely any has been collected so spy satellite images, which were taken in the 1970s and 80s but declassified in 2011, are extremely useful.
By comparing these photographs with satellite images from NASA and the Japanese space agency (Jaxa), the researchers could clearly see how the glaciers were shrinking in size.
The Columbia University researchers observed 650 glaciers in the Himalayas over a 1,243 mile area.
They think an average of eight billion tons of ice has been lost each year between 2000 and 2016.
In the short term, this melted water could cause flooding but the longer term problems could be even worse.
A small amount of glacier melting is important to replenish some of Asia’s rivers in hot weather but once the glacier ice disappears this could lead to droughts and put millions of people in the surrounding areas at risk of losing their water supply.
“Even glaciers in the highest mountains of the world are responding to global air temperature increases driven by the combustion of fossil fuels,” said Joseph Shea, a glacial geographer at the University of Northern British Columbia, who was not involved in the study.
“In the long term, this will lead to changes in the timing and magnitude of streamflow in a heavily populated region.”
This research has been published in the journal Science Advances.
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