The researchers found that the Himalayan glaciers have lost ice ten times more quickly over the last few decades than on average since the last major glacier expansion 400-700 years ago, a period known as the Little Ice Age.
The study, published in the journal Scientific Reports, also shows that Himalayan glaciers are shrinking far more rapidly than glaciers in other parts of the world.
A team led by researchers at the University of Leeds, UK, made a reconstruction of the size and ice surfaces of 14,798 Himalayan glaciers during the Little Ice Age.
They calculated that the glaciers have lost around 40 per cent of their area — shrinking from a peak of 28,000 square kilometres (km2) to around 19,600 km2 today.
During that period they have also lost between 390 cubic kilometres (km3) and 586 km3 of ice, the researchers said.
The water released through that melting has raised sea levels across the world by between 0.92 millimetres (mm) and 1.38 mm, they said.
“Our findings clearly show that ice is now being lost from Himalayan glaciers at a rate that is at least ten times higher than the average rate over past centuries,” said study corresponding author Jonathan Carrivick, from the University of Leeds.
“This acceleration in the rate of loss has only emerged within the last few decades, and coincides with human-induced climate change,” Carrivick said.
The Himalayan mountain range is home to the world’s third-largest amount of glacier ice, after Antarctica and the Arctic and is often referred to as ‘the Third Pole’.
These rivers include the Brahmaputra, Ganges and Indus, they said.
The team used satellite images and digital elevation models to produce outlines of the glaciers’ extent 400-700 years ago and to ‘reconstruct’ the ice surface.
The satellite images revealed ridges that mark the former glacier boundaries and the researchers used the geometry of these ridges to estimate the former glacier extent and ice surface elevation.
Comparing the glacier reconstruction to the glacier now, determined the volume and hence mass loss between the Little Ice Age and now.