Threats from Contracting Glaciers

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    Syllabus: GS1/ Important Geophysical phenomena; GS2/Government Policies & Interventions

    In Context

    • The World Meteorological Organization’s report, the Global Climate 2011-2020, outlined the threats from contracting glaciers.

    Glaciers

    • About:
      • Glaciers around the world can range from ice that is several hundred to several thousand years old.
      • They are formed in areas where the temperatures are exceedingly low, including areas that are at sea level and mostly in high altitude areas like the mountain tops.
      • Today, about 10% of land area on Earth is covered with glacial ice. Almost 90% is in Antarctica, while the remaining 10% is in the Greenland ice cap.
    • Why are glaciers important?
      • Ice acts like a protective cover over the Earth and our oceans. These bright white spots reflect excess heat back into space and keep the planet cooler.
        • In theory, the Arctic remains colder than the equator because more of the heat from the sun is reflected off the ice, back into space.
    • Significance:
      • The Glaciers provide a scientific record of how climate has changed over time. 
      • Through their study, we gain valuable information about the extent to which the planet is rapidly warming

    Melting of Glaciers 

    • Reasons:
      • Since the early 1900s, many glaciers around the world have been rapidly melting. Human activities are at the root of this phenomenon. 
      • Specifically, since the industrial revolution, carbon dioxide and other greenhouse gas emissions have raised temperatures, even higher in the poles, and as a result, glaciers are rapidly melting, calving off into the sea and retreating on land.
    • Outcomes of melting glaciers
      • Rapid glacial melt in Antarctica and Greenland influences ocean currents, as massive amounts of very cold glacial-melt water entering warmer ocean waters is slowing ocean currents. 
      • As ice on land melts, sea levels will continue to rise.
      • Scientists project that if emissions continue to rise unchecked, the Arctic could be ice free in the summer as soon as the year 2040 as ocean and air temperatures continue to rise rapidly.

    Global Climate 2011-2020 report highlights

    • The Global Climate 2011-2020, gives a broad view of the planet’s response to greenhouse gas emissions. 
    • Melting & thinning of Glaciers:
      • In the section on the state of glacier health, it points out that, on average, the world’s glaciers thinned by approximately a metre a year from 2011 to 2020. 
      • When compared across decades, there is significant regional variability, but the overall pattern remains that glaciers in all regions of the world are becoming smaller. 
      • Some of the reference glaciers, which are used to make long-term assessments of glacier health, have already melted away as the nourishing winter snow is completely melting away during summer.
        • In Africa, glaciers on the Rwenzori Mountains and Mount Kenya are projected to disappear by 2030, and those on Kilimanjaro by 2040
    • GLOF:
      • The report points to the rapid growth of pro-glacial lakes and the likelihood of glacier lake outburst flood (GLOF), posing additional threats to ecosystems and livelihoods. 
      • The reports singled out how the water from glacial melt contributed to one of the decade’s worst flooding disasters, the Uttarakhand floods of June 2013.
    Glacial Lakes
    – A glacial lake is a body of water that originates from a glacier. It typically forms at the foot of a glacier but may form on, in, or under it.
    Glacial Lake Outbursts Floods (GLOF)
    – As glacial lakes grow larger in size, they become more dangerous because they are mostly dammed by unstable ice or sediment composed of loose rock and debris. 
    – In case the boundary around them breaks, huge amounts of water rush down the side of the mountains, which could cause flooding in the downstream areas. 
    A. This is called glacial lake outburst floods or GLOF.
    – These lakes are often found in steep, mountainous regions, which means landslides or ice avalanches can sometimes fall directly into the lakes and displace the water, causing it to over-top the natural dam and flood downstream.
    A. In 2013 Uttarakhand’s Kedarnath witnessed flash floods along with a GLOF caused by the Chorabari Tal glacial lake, killing thousands of people.
    B. The Chungthang dam in Sikkim was recently destroyed after the South Lhonak Lake flooded from a melting glacier, triggering catastrophe downstream.

    Melting of Himalayan Glaciers

    • Significance:
      • Himalayan glaciers are of paramount importance in the Indian context, especially for the millions of dwellers living downstream who rely on these perennial rivers for their day-to-day water needs.
      • The Himalayan mountains are also referred to as the third pole because they hold the world’s third-largest amount of glacier ice, following Antarctica and the Arctic. 
    • Challenge of Climate change & melting of Himalayas:
      • A recent report by the International Centre for Integrated Mountain Development found that the disappearance of glaciers in the Hindu Kush Himalayas was “65% faster in the 2010s than in the previous decade”. 
      • At the current rate of global greenhouse gas emissions, which is expected to see temperatures increase by 2.5°-3°C by the end of the century, the volume of glaciers is forecast to decline anywhere from 55% to 75%.
        • This means sharp reductions in freshwater supply in the immediate vicinity of 2050. 
      • Despite awareness of the risks posed by Himalayan glaciers there is no early warning system for the likelihood of GLOF events. 

    Suggestions & way ahead

    • The sensitivity of glacier systems to warming underlines the need for their careful monitoring. 
    • Correspondingly, there is a need to make comprehensive risk assessments, map regions of vulnerability and commission infrastructure development with the highest standards of care.
    • Much like warnings before cyclones, floods and earthquakes, authorities must elevate threats from contracting glaciers to the same category of risk.
    Daily Mains Question
    [Q] Examine the significance of Glaciers for the environment. What are the challenges posed by melting of glaciers in India & globe?