Context: Scientists have found a seasonal advancement in surge-type glaciers in the Karakoram Range of Ladakh through detailed assessment of some major surging glaciers of the Karakoram range.
More on the news:
- Scientists from Wadia Institute of Himalayan Geology(WIHG), Dehradun an autonomous institute under the Department of Science & Technology have made this assessment using satellite images (Landsat 8 OLI, ASTER and Sentinel-2), Digital Elevation Models (DEM) and thermal data.
- The scientists focused on the Shispare and Muchuhar glaciers, former tributaries of the once larger Hasanabad Glacier situated in Hunza Valley, Gilgit-Baltistan, Pakistan.
- In 2017–2019, a surge of Shispare Glacier formed an ice-dammed lake and generated a small Glacial Lake Outburst Flood (GLOF).
‘Surging’ or ‘Surge-type’ glaciers:
- Are a certain type of glaciers that have shown advancement in volume and length over a period of time.
- The Surge-type glaciers oscillate between brief (months to years) rapid flow and lengthy (tens to hundreds of years) slow flow or stagnation, which are called the ‘active’ (or ‘surge’) and ‘quiescent’ phases, respectively.
- This unsteady glacier flow makes it difficult to accurately assess individual glacier mass balances using in-situ observations because of the uncertain outcomes.
- Subglacial processes and conditions like amount of debris, distribution of stored water, and temperature gradient are crucial to understand the diversity of surge-types and surge-like behavioural spectrum.
However, such information has been rare or unknown in the Karakoram, because ground-based observations are difficult to acquire.
Why a cause of worry?
- The surging terminates in summer due to channelized flow of meltwater and considerable heterogeneity in movement is also observed during summer and springtimes.
- The behaviour of these glaciers, which represent 40% of the total glaciated area of the Karakoram goes against the normal trend of considerable reduction in volume and length of most glaciers in the Himalaya in recent decades.
- Surging of glaciers is potentially catastrophic as it can lead to the destruction of villages, roads and bridges.
- It can also advance across a river valley and form an ice-dammed lake. These lakes can form catastrophic outburst floods.
- Therefore, monitoring of glacier surges, ice-dammed lake formation, and drainage is of paramount importance.
Significance: The study published in the journal Nature, Scientific Reports will help to understand the diversity of glacial behaviour and help make accurate assessments of individual glacier mass balances for disaster planning and management.
A glacial lake outburst flood (GLOF) is a release of meltwater from a moraine or ice-dam glacial lake due to dam failure.
A moraine is any glacially formed accumulation of unconsolidated glacial debris (regolith and rock) that occurs in both currently and formerly glaciated regions on Earth (i.e. a past glacial maximum), through geomorphological processes.
A glacier is a moving mass of ice at speeds averaging a few meters a day. A glacier is charged with rock debris which is used for erosional activity by moving ice. A glacier during its lifetime creates various landforms which may be classified into erosional and depositional landforms.
- Types of Glaciers: Continental glaciers, ice caps, piedmont glaciers and valley glaciers.
- The continental glaciers - Found in Antarctica and in Greenland and the Antarctic ice sheet is the largest block of ice on earth.
- Ice caps - These are the covers of snow and ice on mountains from which the valley or mountain glaciers originate.
- The piedmont glaciers - They form a continuous ice sheet at the base of mountains as in southern Alaska.
- The valley glaciers - They are found in higher regions of the Himalayas in India and all such high mountain ranges of the world. They are also known as Alpine glaciers.
- The largest of Indian glaciers occur in the Karakoram range - Siachen (72 km), while Gangotri in Uttar Pradesh (Himalayas) is 25.5 km long.