Very rapid melting of Himalayan glaciers - Latest research

The rapid melting of Himalayan glaciers and reasons

Very rapid melting of Himalayan glaciers - Latest research

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• The story: Latest resarch has found that the Himalayan glaciers 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 water released through that melting has raised sea levels across the world by between 0.92 millimetres (mm) and 1.38 mm. This research was by the Wadia Institute of Himalayan Geology.
• Details: It says that glaciers in the Himalayas were melting at an "exceptional" rate because of global warming, threatening the water supply of millions of people in Asia. The study showed that Himalayan glaciers were shrinking far more rapidly than glaciers in other parts of the world.

1. 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.
2. 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.
3. During that period they have also lost between 390 cubic kilometres (km3) and 586 km3 of ice.
4. Ice now being lost from Himalayan glaciers is at a rate at least ten times higher than the average rate over past centuries. This acceleration in the rate of loss has only emerged within the last few decades, and coincides with human-induced climate change.

• Implications of it: 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'. The acceleration of melting of Himalayan glaciers has significant implications for hundreds of millions of people who depend on Asia's major river systems for food and energy. These rivers include the Brahmaputra, Ganges and Indus. 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.

1. 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.
2. Comparing the glacier reconstruction to the glacier now, determined the volume and hence mass loss between the Little Ice Age and now.
3. The Himalayan glaciers are generally losing mass faster in the eastern regions -- taking in east Nepal and Bhutan north of the main divide.

• Which are more vulnerable: 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 are also declining faster where they end in lakes, which have several warming effects, rather than where they end on land. The number and size of these lakes are increasing so continued acceleration in mass loss can be expected. Glaciers which have significant amounts of natural debris upon their surfaces are also losing mass more quickly, contributing around 46.5 per cent of total volume loss despite making up only around 7.5 per cent of the total number of glaciers.
• Summary: Governments must act urgently to reduce and mitigate the impact of human-made climate change on the glaciers and meltwater-fed rivers, and the modelling of that impact on glaciers must also take account of the role of factors such as lakes and debris. Clearly, there's a massive danger awaiting populations downstream.
• EXAM QUESTIONS: (1) Explain the important role Himalyan glaciers play in the ecology of the region. (2) What is the "third pole of planet Earth"? Explain.

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