Every year, World Water Day is observed on 22nd March worldwide under the aegis of the UNO to highlight different crises facing by the world community on matters relating to water. This year’s theme is “Preserve the Glaciers of the World.” When snow accumulation is greater than it melts, glaciers are formed, serving as the largest reservoir of fresh water on Earth and second only to the ocean as a reservoir of total water. A glacier is considered ‘in balance’ when the amount of snow that falls and accumulates at its surface is equal to the amount of ice lost through melting, evaporation, calving, and other processes. A glacier is a river of ice often covered with snow and ice, slowly moving down a valley from a mountain range with melt water. Some glaciers are moving at a slow pace, a few centimetres per year, while others move several metres per day. The formation of glaciers took millennia; their size varies depending on the amount of ice they retain throughout their lifespan. The oldest glacier is in Antarctica, 1,000,000 years old, and the other in Greenland is 100,000 years old. Glaciers that exist today are mostly remnants of the last ice age. Glaciers are very critical for sustaining life, ecology, and maintaining the water cycle. The rapid retreat of glaciers in modern times threatens water availability, increasing the risk of food and energy security, as well as natural disasters like floods, landslides, and droughts, etc., hence necessitating trans-boundary cooperation.
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The seriousness of the problem can be understood by the fact that during 2023, glaciers lost 600 gigatonnes of water, the largest mass loss in the last 50 years. About 70% of Earth’s fresh water is stored in ice or snow. There are 275,000 glaciers worldwide, covering approximately 700,000 square km. Glaciers act as a protective cover for the Earth, reflecting heat back into space and keeping the planet cool, a phenomenon known as the albedo effect. There are three places in the world where most of the ice is concentrated: the largest is Antarctica, followed by Greenland, and the Himalayan Glaciers (HKG), known as the “Third Pole,” are home to thousands of glaciers. Glaciers melt depending on the rise in Earth’s average temperature. Other climatic factors include rainfall, snowfall, etc., and non-climatic factors include location, altitude, topography, slope, glacier bed, and deposits of black carbon and pollutants. Switzerland saw a glacier loss of 10% of the total mass between 2022-2023. It is a matter of great concern that 1/3 of the present heritage sites will disappear by 2050.
Glaciers support more than 2 billion people by replenishing their rivers, lakes, and groundwater, supporting ecosystems, agriculture, energy generation, industry, and, most importantly, drinking water. Earth's glaciers have been unnoticeably retreating since 1850, but more remarkably in modern times due to climate change. Melting glaciers is an inexorable forward march. Consequently, 9.6 billion tonnes of glaciers have melted since 1961. When the temperature is rising, glaciers melt at faster rates than glaciers can form, leading to retreat.
Environmental scientists are of the opinion that by limiting the average temperature to 1.5 degrees Celsius, Earth can still save 2/3 of the world heritage glacier sites. World heritage glaciers are losing an average of 58 billion tonnes of ice per year. According to the United Nations University, between 2000 and 2019, glacier loss was 267 gigatonnes per year. Severe meltdown produces the maximum volume of water runoff, known as ‘peak water,’ after which water flow decreases abruptly because of the shrinkage of glaciers. It is estimated that 2 billion people are at risk of negative effects regarding water scarcity and livelihood loss due to glacier meltdown. The Hindu Kush Himalayan Mountain glacier, which extends 2,175 miles from Afghanistan to Myanmar, is of much interest to India. It contains the largest volume of ice on Earth outside the two polar regions and is a source of water for 12 rivers, including the Brahmaputra, Ganges, Indus, etc., that flow through 16 Asian countries, feeding 240 million people directly and supporting about 1.65 billion people further downstream, better known as the Third Pole. It is a point of great concern that the HKH will shed 80% of its ice by the end of the century. It is estimated that if the temperature rise is within the following limits, the HKH will lose ice as follows: between 1.5-2 degrees Celsius, it will lose 30-50%, 3 degrees Celsius will lead to a 75% loss, and 4 degrees Celsius will result in an 80% loss of its ice by 2100.
Simulations project that a 4-degree Celsius rise in temperature would eliminate nearly all the world’s glaciers. Melting of Greenland glaciers could be triggered at a temperature even at a lower temperature rise of 2-3 degrees Celsius due to the lower elevation.
When glaciers retreat, lakes are formed behind the newly exposed terminal moraine. Rapid accumulation and expansion of water in these lakes are evident and can lead to the sudden breaching of the unstable natural dams behind which they are formed, resulting in a sudden discharge of a huge amount of water and debris, known as “Glacier Lake Outburst Floods” (GLOFs), which often lead to catastrophic effects. There have been at least 21 recorded GLOF events so far in Nepal, Tibet, and Bhutan. Recent satellite imagery has revealed a significant increase in the number and size of glacier lakes, with 676 lakes identified as expanding since 1984, posing a direct threat to downstream communities in the event of a burst or overflow. India’s agriculture relies on glacier meltwater for 70% of its needs. In addition, there is a health risk, too, as ancient viruses and bacteria locked in ice could infect wildlife and cause zoonotic diseases. Melting glacier water may also carry toxic contaminants used in the past. The expected mean temperature rise could be anywhere between 1.4-5.8 degrees Celsius worldwide in the coming years, with the Indian subcontinent expecting a rise between 3.5-5.3 degrees Celsius. Alpine glaciers have shrunk by 40% in area and more than 50% in volume since 1850. Similarly, if Greenland’s ice sheets were to melt completely, sea levels would rise by 20 feet. At the moment, sea levels are rising at the rate of 0.74 mm per year.
The chief reason for the melting of glaciers is the increase in the concentration of carbon dioxide in the atmosphere, along with other greenhouse gases (GHGs) produced by human activities in industries, transport, deforestation, and, most remarkably, the burning of fossil fuels for power production, which are responsible for warming our planet. Carbon blacks and other pollutants that settle on glacier surfaces reduce their albedo (reflection) effect, increasing heat absorption. Other potential driving causes are hydrological changes such as precipitation patterns, exacerbated by climate change, which aggravates both flooding and drought conditions. Switching to renewable clean energy, efficient use of energy and water, afforestation, and adopting the Reduce-Recycle-Reuse principle are a few measures to reduce carbon footprints.
(All views and opinions expressed are author’s own)