#GS3 #Environment 

A recent 20,000-tonne oil leak at an Arctic region power plant in Russia that is now being recognised is the sinking of ground surface due to permafrost thaw. 

What is permafrost? 

  • Permafrost is ground that remains completely frozen at 0 degrees Celsius or below for at least two years. It is defined solely based on temperature and duration. The permanently frozen ground, consisting of soil, sand, and rock held together by ice, is believed to have formed during glacial periods dating several millennia. 
  • These grounds are known to be below 22 per cent of the land surface on Earth, mostly in polar zones and regions with high mountains. They are spread across 55 per cent of the landmass in Russia and Canada, 85 per cent in the US state of Alaska, and possibly the entirety of Antarctica. 
  • In northern Siberia, it forms a layer that is 1,500 m thick; 740 m in northern Alaska. At lower latitudes, permafrost is found at high altitude locations such as the Alps and the Tibetian plateau. 
  • While permafrost itself is always frozen, the surface layer that covers it (called the “active layer”) need not be. In Canada and Russia, for example, colourful tundra vegetation carpet over permafrost for thousands of kilometres. Its thickness reduces progressively towards the south, and is affected by a number of other factors, including the Earth’s interior heat, snow and vegetation cover, presence of water bodies, and topography. 

Role of climate change  

  • A study has shown that every 1 degree Celsius rise in temperature can degrade up to 39 lakh square kilometre due to thawing. This degradation is expected to further aggravate as the climate gets warmer, putting at risk 40 per cent of the world’s permafrost towards the end of the century– causing disastrous effects. 
  • When permafrost thaws, microbes start decomposing this carbon matter, releasing greenhouse gases like methane and carbon dioxide.  
  • Researchers have estimated that for every 1 degree Celsius rise in average temperature, permafrost grounds could release greenhouse gases to the tune of 4-6 years’ of emissions from coal, oil, and natural gas — becoming a major factor of climate change in themselves. 

Threat to infrastructure  

  • As temperatures rise, the binding ice in permafrost melts, making the ground unstable and leading to massive potholes, landslides, and floods. The sinking effect causes damage to key infrastructure such as roads, railway lines, buildings, power lines and pipelines that serve more than 3.5 crore people that live in permafrost regions. These changes also threaten the survival of indigenous people, as well as Arctic animals. 
  • Soil subsidence is a major cause for concern in Siberia, where ground levels have collapsed by more than 85 metres in some parts. 
  • In Canada and Alaska, the costs of repairing public infrastructure are escalating. As per an Arctic Council report from 2017, melting ice would make infrastructure foundations unable to withstand loads that they were able to during the 1980s — a finding that has been corroborated by the owners of Russia’s oil leak site, who said after the incident that the fuel tank’s supporting pillars had held it in its place “for 30 years without difficulty”. 
  • Cause of diseases – 
  • Beneath its surface, permafrost contains large quantities of organic leftover from thousands of years prior — dead remains of plants, animals, and microorganisms that got frozen before they could rot. It also holds a massive trove of pathogens. 
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