A new study has warned that the Himalayan glaciers could be melting at an “exceptional rate” and threaten water supplies for many millions in Asia.
Researchers have found that Himalayan glaciers have lost ice 10 times more quickly over the last few decades – predominantly since the year 2000 – than on average since the Little Ice Age hundreds of years ago.
The Little Ice Age, a time of great mountain-glacier expansion from the late 14th century onwards to the middle century when the rivers stopped flowing and the crops became ruined, was an era that saw the end of the Ice Age.
The study found that Himalayan glaciers are now retreating faster than other glaciers around the globe, which in turn is increasing sea level.
This accelerating melting has implications for hundreds of millions of residents who depend on Asia’s major rivers for food and energy – including the Brahmaputra, Ganges and Indus.
Research has shown that Asia’s water supplies are at risk from the rapid melting Himalayan glaciers. Pictured is the tongue of Khumbu Glacier in the Himalayas. Khumbu Glacier is the world’s highest glacier
Exemplary from Langtang in the Himalaya showing geomorphological evidence including moraines and trimlines. These are used to calculate past glacier depths (B), and reconstruct old glacier surfaces (A).
The Himalayan mountain range – often referred to as ‘the Third Pole’ – is home to the world’s third-largest amount of glacier ice after Antarctica and the Arctic.
Senior lecturer at University of Dundee in geography and environment science, Dr Simon Cook is the study author. He said that people living in the Himalayan area are already seeing drastic changes.
Dr. Cook stated, “This research confirms that these changes are rapidly occurring and will have an important impact on whole nations and regions.”
The team did a reconstruction of 14 798 Himalayan glaciers’ ice surface during the Little Ice Age.
Although the Little Ice Age was a period that lasted between the 16th and the 19th centuries, some believe it started earlier.
To reconstruct the ice surface, the team relied on digital elevation models and satellite imagery to create outlines of 400-700 year ago glacier extent.
Satellite images showed ridges marking the boundaries of glaciers, just as they were in the “Little Ice Age”.
The geometry of the ridges was then used by researchers to determine the extent of the glacier and the elevation of the ice.
The volume loss and mass change between the Little Ice Age (now) and the Glacier Reconstruction were determined by comparing the two.
A chain of ponds at the Khumbu Glacier in the Himalayas is shown. Himalayan glaciers are also rapidly shrinking, faster than those in other areas of the world.
Around the 17th century, Earth experienced a prolonged cooling period dubbed the Little Ice Age that brought chillier-than-average temperatures to much of the Northern Hemisphere
The researchers calculate that the glaciers have lost around 40 per cent of their area – shrinking from a peak of 10,800 square miles (28,000 km2) to around 7,560 (19,600 km2) today.
During that period they have also lost between 93.5 cubic miles (390 km3) and 140 cubic miles (586 km3) of ice – the equivalent of all the ice contained today in the central European Alps, the Caucasus and Scandinavia combined.
Based on calculations by the team, sea levels have risen between 0.03 in (0.92mm) and 0.05 inch (1.38mm) due to melting.
The Himalayan glaciers are generally losing mass faster in the eastern regions – taking in east Nepal and Bhutan north of the main divide.
The study suggests this variation is probably due to differences in geographical features on the two sides of the mountain range and their interaction with the atmosphere – resulting in different weather patterns.
Himalayan glaciers will also be more vulnerable to melting if they are in lakes than they are on the ground.
As these lakes grow in number and size, it can be expected that mass loss will continue to accelerate.
Glaciers that have large quantities of natural debris are also losing mass faster.
They contributed around 46.5 per cent of total volume loss despite making up only around 7.5 per cent of the total number of glaciers.
Lobuche, an iconic mountain in Nepal, is shown here. It lies next to the Khumbu Glacier (the world’s tallest glacier).
‘This acceleration in the rate of loss has only emerged within the last few decades, and coincides with human-induced climate change,’ said study author Dr Jonathan Carrivick at the University of Leeds School of Geography.
“Although we need to urgently reduce the effects of climate change on glaciers and meltwater fed rivers, modelling the effect on glaciers should also consider the contribution of other factors like lakes and debris.
The Himalayan Region includes countries such as Nepal, China, India and Nepal. It is also home to Mount Everest which rises 29,032ft.
The region has the largest concentration of ice on Earth, apart from the polar caps, and provides around 86,000,000 cubic metres of water annually, according to the WWF.
These mountains are often called the “water towers in Asia” and include K2, which is the second highest mountain in the world at 28.251 feet.
Scientific Reports published the new study today.