The world's "third pole" has shrunk at a breathtaking pace in recent decades as climate change has increased temperatures worldwide.
A new peer-reviewed study finds that the accelerating melting of Himalayan glaciers is also outpacing the shrinkage of glaciers elsewhere in the world, putting them in a class scientists call "exceptional."
"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 Jonathan Carrivick, report author and deputy head of the University of Leeds School of Geography, in a statement. "This acceleration in the rate of loss has only emerged within the last few decades, and coincides with human-induced climate change."
The Himalayan mountains are often referred to as the third pole because they hold the world's third-largest amount of glacier ice behind Antarctica and the Arctic.
Carrivick and colleagues used satellite images and digital models to reconstruct nearly 15,000 Himalayan glaciers to their size and state during the so-called Little Ice Age 400 to 700 years ago. They found that the total area occupied by ice has shrunk by around 40% from its peak to today.
The total amount of ice melted equals all the ice found today in the central European Alps, Caucasus and Scandinavia combined. The meltwater released in the process has contributed around a millimeter to rising sea levels.
The study was published online Monday in the journal Scientific Reports.
"The acceleration in glacier loss that we have witnessed has likely been prompted by climate change, the effects of which are very concerning for millions of people who depend on these glaciers and the rivers they feed," said co-author and glaciologist Simon Cook from the University of Dundee in Scotland.
Annual melt from Himalayan glaciers feeds major rivers in Asia like the Ganges that support agriculture and other critical uses for large populations.
"Glacier melt is a normal process, and indeed desirable in terms of water supply," added Cook. "But what is alarming is the rate at which this melt is now happening and that the glaciers are losing more mass than they are gaining through snowfall."
The study also found glaciers declining faster where they end in lakes and where there are significant amounts of debris on their surfaces.
"While we must act urgently to reduce and mitigate the impact of human-made climate change on the glaciers and meltwater-fed rivers, the modelling of that impact on glaciers must also take account of the role of factors such as lakes and debris," Carrivick said.
Cook adds that people in the region "are already seeing changes that are beyond anything witnessed for centuries."
"This research is just the latest confirmation that those changes are accelerating and that they will have a significant impact on entire nations and regions."